Wiring diagram - advice please (photos)
 

I've put on a few posts recently with similar questions. Ignore them all. This is the Final Question to complete my cruise control retrofit. Jamie Welch handsomely configured my ZT with T4 this morning - thanks again.:bowdown: I got a clean bill of wiring health but there is a brake switch conundrum preventing it from working which I need someone's knowledge about. Please refer to the two diagrams in conjunction with the issue.

Context
• My KV6 was built without cruise and interlock
• The brake switch has all four wires connected
• Header C0285 is missing from the car. That mostly makes sense as it deals with cruise and parking sensors, none of which my car has
• The green/red (GR) wire from the brake switch pin 3 (C0775-3) is connected to the electronic auto transmission (EAT) pin 43 (C0932-43) in line with its pre-cruise state. It currently functions exactly the same as the wire from C0775-4 which controls the brakes lights i.e. power appears when the brake pedal is depressed. I do not know if it would function this way if the car was OEM-fitted with cruise as there may be two switch types (one is referred to at Rimmers as double pole, and is shown (only once) on a RAVE wiring diagram as double pole).
• Whilst T4 confirms the brake lights functioning correctly from C0775-4, it however reports the brakes being permanently on based on C0775-3. This is despite both pins C0775-3 and -4 behaving identically. This alone appears to be preventing cruise from working.
• Pin 6 on the cruise control relay (C0895-6) requires to be connected to C0775-3; in the absence of header C0285, I piggybacked off the EAT C0932-43 as above, to C0895-6. The GR wire colours are also consistent. I am however now doubting whether this is correct based on the attached diagrams.

Wot I need help with
• I do not know if the OEM brake switch is double-pole. It's only shown once in the entire ZT wiring diagrams as being double-pole and is not shown as such on the attached diagrams. Might this be making any difference to how pin 3 behaves - perhaps open when pin 4 is closed and vice versa?
• Should I disconnect the EAT C0932-43 from the brake switch C0775-3 now that cruise is fitted? I'm unable to interpret the diagram in that respect.
• Finally, the smaller of the two attached diagrams shows C0932-43 being connected twice to the missing C0285 (pin 2 and pin 3). Is it safe to assume that I can disconnect the brake switch C0775-3 from EAT C0932-43 altogether and instead connect it directly to the cruise relay C0895-6?

That's what my brain took me before I wrote this down, and it still arrives at the same point.

I realise wiring isn't everyone's bag but it's straightforward for others. I've always had a good knowledge but have limitations. Someone more qualified help will be hugely appreciated. Thanks in advance.

Dougie.

https://www.the75andztclub.co.uk/for...77770be678.jpg

https://www.the75andztclub.co.uk/for...777710cad0.jpg

So this is the only reference I can find to the brake switch which shows it as a double pole unit. I'm stlll unable to determine what this means in terms of how it operates. All the evidence suggests I have a single-pole unit.

Pin 1 is from fused power
Pin 2 is to earth
Pin 3 is to cruise relay
Pin 4 is to brake lights

???

https://www.the75andztclub.co.uk/for...860ca380a6.jpg

Hi Dougie,

The internal detail of the brake pedal switch in your diagrams is unofficial as far as I can tell. RAVE doesn't include it so it may or may not be correct.
RAVE says that C0932-43 is an input to the EAT ECU from the brake pedal switch. In other words, it tells the automatic transmission when the driver is braking. I'd say that you should not disconnect it!
It appears to me as if C0775-3 needs to be connected to both the EAT ECU C0932-43 and the cruise relay C0895-6 (both are inputs from the brake pedal switch).

Simon

Hi Simon,

All the diagrams are from Rave including the exploded brake switch one.

C0932-43 is indeed an input from C0775-3, and it works. I agree that disconnecting the EAT on that basis, isn't logical. In any case, I disconnected C0932-43 and tried connecting F0775-3 direct to the cruise relay C0895-6 but it made no difference.

So I'm left with with the question of why there are two OEM brake switches available, one double pole and one single pole, and why T4 was reporting cruise control as believing the brakes are on permanently.

Dougie.

Hi Doug, yes the internal detail of the double pole brake switch is shown on the exterior brake and reverse lamps part of my wiring diagrams too ;)

https://the75andztclub.co.uk/forum/a...1&d=1593344863

I've checked the supercession lists on my EPC, and the original white double pole brake switch has now been replaced with XKB000022A, so a cheaper Land Rover alternative is XKB000022

So I would start by making sure the switch fitted to your car is the correct one, then take it from there ;)

Brian :D

I'm collecting an XKB000022A tomorrow morning from Rimmers which I ordered yesterday after the T4 session. They also stock the XKB000022 but I can't see any spec difference. Neither are described as double-pole whereas XKB000090 is (https://rimmerbros.com/Item--i-XKB000090).

Do you read the switch as needing to be double-pole?

According to an older thread, the Land Rover switch isn't compatible.

https://the75andztclub.co.uk/forum/s...3&postcount=14

Dougie.

The switch needs to be double pole, and to be fair the XKB000022 is listed for the L322 so that will be an auto, and it will be fitted with cruise, and I suspect the correct double pole switch.

The original part number prior to supercession is as follows

XKD000010

Description

Switch-stop/cruise brake - White, double pole C

https://www.the75andztclub.co.uk/for...9&d=1593347180

And the following applies to the supercession XKB000022 switch

Product Description

Up to VIN 5D345691 the brake light switch may have been coloured white for cars with cruise control fitted but this black switch is now suitable for those applications.

Brian :D

Thanks for that Brian. Unless I'm able to verify whether both elements of a double pole switch act in any way other than identically to each other, I conclude that my existing switch is doing its job on both outputs. In which case, it's a red herring.

I may need another T4 session.

What colour switch is currently fitted? is it white or black?

The alternative is to buy a used switch from a breaker, originating from a KV6 auto fitted with cruise ;)

Brian :D

I've not managed to contort yet to see. :shrug: But as it's talking to the EAT (and now the cruise relay) correctly, I've little reason to doubt it's faulty. So I'm currently stuffed. :banghead:

Dougie.

Dougie; I recall from other threads that the brake pedal switch works on an electromagnetic principle. Is it possible that yours needs adjusting? You could place a multimeter across pins 2 & 4 and check that the switch operates correctly.

Simon

Dougie, have you checked that you have made BOTH connections?

Simon

It's a hall effect switch Simon not a magnetic reed switch, and the automatic models with cruise have a two pole switch, pole 1 connects to the LSM for the brake lights, and pole 2 to the cruise ECU.

According to your wiring diagrams this appears to be incorrect. Your diagram shows the brake pedal switch making pins 1 & 3 (sending +12v to two ECUs) but pins 2 & 4 sends an earth to the LSM, ABS ECU, cruise "relay" and cruise ECU, i.e. not exactly the same function.
This suggests that there may be a problem with your brake pedal switch.
I can't find C0285. Do you mean C0288?

Simon

Dougie, take a look HERE

Brian :D

A Hall effect switch is an electromagnetic switch Brian.
Why does my RAVE wiring diagram show both the LSM and cruise ECU being connected to terminal 4 (which makes to terminal 2)?

Simon

Does this help Simon, Dougie is referring to header 0285, I've highlighted it for you, it's just below the picture of the double pole switch ;)

https://the75andztclub.co.uk/forum/a...1&d=1593360770

Simon, is yours a KV6?

Dougie.

Yes, and it has cruise!

Simon

I don't have any idea Simon, which version of RAVE do you have? there are at least five different revisions.

The diagram I'm looking at currently are RCL 0310 ENG Circuit Diagrams R.H.D.

I'm fairly confident Dougie has the incorrect switch fitted to his car, it has been seen on a few occasions now where people have retrofitted cruise.

Thanks because that header is labelled C0288 on my RAVE (2003 version).
It appears that our diagrams have major differences which is odd.

Simon

So you must be looking at RCL 0417 ENG then Simon?

It's the same joint though, although labelled differently is somewhat confusing I agree.

I'm off to walk the dog, I'll leave it with you and Dougie ;)

Brian :D

I'm looking at RCL 0544 ENG.

Simon

Simon, you're quite correct about the earth on pins 2 & 4 - I incorrectly referred to them as sending +12v. However, the brake lamps operate correctly; it's possible that one or both of my additional connections to the cruise relay and/or ECU is bad though which would mean an incomplete earth, and I'll check that.

Pin 1 as you'll see brings +12v to the second pole (pin 3) which is then sent via pin 3 to the EAT and cruise relay when the brake pedal is pressed. That is functioning correctly.

Regarding C0285, it's shown on pages 34 & 36 of Rave, and also on the Header Joints page 109. If you check out the C0285 Connector Detail in the library, it confirms pins 1-4 as being grouped and GR in colour. However my car does not have a C0285 header as it doesn't have interlock*, cruise or parking sensors. *incorrect, it does but without requiring brake input

The fact that half of the switch completes an earth and the other half completes a +12v connection, must mean that it is in fact a double pole switch. Yes?

Dougie.

I'l be more than happy if it is wrong Brian, but we've established that one pole is correctly operating an earth circuit and the other pole is correctly operating a +12v one. That's confirms double pole.

Dougie.

Yes, but remember that as it's a Hall effect device there are no moving parts.

Simon :}

This also puzzles me Dougie. Your signature says that your car is a 180 sports auto so surely it must have the interlock unit.

Simon

Yes, true. :) I went out & checked pin 9 on C0286 which is the GP wire from the switch pin 4 (C0075-4). My reasoning for connecting to that header was that the switch pin 4 wire was/is inaccessible without some more surgery, and I made the assumption that it connects directly from C0775-4 to C0286-9 (9-11 are common). Pin 9 (and 10 and 11) on that header however tests as permanently earthed which will be one good reason why cruise thinks the brake pedal is pressed. The brake lamps work correctly so it's clear that my assumption was wrong, despite the diagram saying it was right.

Thanks guys for your input this afternoon - it's much appreciated. I'm in a much clearer place despite not yet having cracked the job, as a result. It's clear that I'm going to have to change the switch which I'm collecting from Rimmers in the morning, although I still don't understand why the connections from (allegedly) pin 4 test as permanently earthed despite the brake lamps working correctly. Perhaps my version of Rave isn't correct relative to my car. :shrug: Or more likely I'm missing something. Either way, here's to tomorrow.

Dougie.

How did you test it Dougie?
:confused:
They're triggered, via the LSM, from the same C0286 header which you say is permanently earthed. How can that be?

Simon

Here is the cruise switch overview, showing the two separate switch states used for the brake lights and the cruise control


https://www.the75andztclub.co.uk/for...1&d=1593381154

https://www.the75andztclub.co.uk/for...1&d=1593381177

Now you've no idea how difficult this was to photograph, as the time differential between the two switches actuating is almost instantaneous.

https://www.the75andztclub.co.uk/for...1&d=1593381177

Normally you would see either this.......

https://www.the75andztclub.co.uk/for...1&d=1593382149


Or indeed this......

https://www.the75andztclub.co.uk/for...1&d=1593382215


Brian :D

With the positive meter probe on a live point and the negative probe on C0286-9/10/11. My assumption was that when the brake pedal is not depressed, the switch is open between pins 2 & 4 and therefore the earth should not be made from the LSM. It's behaving though as if the pedal was depressed if my logic is correct?

That's my point. I don't know. I also checked the LSM switch pin 25 which shows as running to C0286 and then to C0775-4, which also made to earth. Am I wrong in believing that pressing the pedal closes the switch, completes the earth coming from the LSM, and illuminates the brake lamps?

Brian, what was shown on Jamie's screen was exactly what you've put above on the third photo although I'm now unsure whether switch 1 was on and switch 2 was off, or vice versa. I can see it's relevant so I've PMd Jamie to see if he remembers.

Dougie,

Brake pedal switch measurements
 

So you were measuring voltage then and to be more precise, the p.d. between the battery positive and the brake pedal switch pin 4.

The theory of the Hall effect device is that when it is subject to a magnetic field (which we're assuming corresponds to depressing the brake pedal) a low voltage is produced across its output (which we're assuming is pins 2 and 4). This suggests that it's not a zero resistance switch as shown in your wiring diagrams. This is why I am suspicious that they have been re-drawn from the original MGR drawings but Brian says that this is not the case. A further conundrum is that his document reference precedes mine!

Back to your measurement Dougie. What did you see on your voltmeter with the brake pedal in both positions?

Simon

So when the ignition is on and brake pedal depressed, it shows 3.7v. When the pedal is at rest, it's 11.84v.

Dougie.

Opposite of the third image, the brake switch says it is constantly pressed and the brake light test passes perfectly fine, I'm with Brian and think it's the switch that is causing all the headache.

Thanks Jamie. I'm about to collect the new switch and will hopefully get it fitted today. I'm now at a loss though given that +12v is being supplied to the EAT C0932-43 as it always has; all I've done is piggybacked off that to the cruise relay C0895-6. I can't see how a new switch is going to change that.

Dougie.

In which case Dougie if you remove your piggybacked feed to C0895-6 (the cruise "relay"), does the fault remain? That should determine whether your addition is guilty or innocent.

Thanks Dougie, that's very interesting and appears to correlate with the results from Jamie's T4.

Simon

I removed the feed as you suggested and cruise still doesn't work. As I don't have access to T4, I obviously can't say how it would read without the connection. It seems to me though that that GR feed from the brake switch pin 3 is doing what it's supposed to, and the other GP earth "feed" from pin 4 is earthing when it shouldn't.

I'm only getting one (DME) error on TOAF now which I can't see to identify and which appeared after the T4 session. There are no LCM or IKE errors now. The yellow IPK cruise light isn't lighting up at all at any speed but the paddles tested ok on T4.

I'll take your word for it.:D Just about to remove the driver's seat and attack the switch.

Dougie.

That's not what Jamie has said Dougie. Look here ....
As I understand it, T4 calls terminals 1 & 3 the "brake switch" and 2 & 4 the "brake light test" (see MarinaBrian's screenshots).
Good; that eliminates your new feed.
New question!
This is fed from the cruise ECU C0239-11 to header C0291-11>13 to the instrument pack. Do you have a voltage there? If not:

Is the tiny green LED in the cruise control on/off button illuminating?
Are you seeing +12v ignition on the cruise "relay" C0895-8?
When the on/off button is pressed, do you see +12v at C0895-12?

Simon

Noted, thanks.

Well it isn't actually because C0291 on my car has pins 11-14 missing. I therefore added the missing EAT C0932-49 brown wire and split-connected C239-11 and the light C0230-5 to that. The pump C0228-5 splits from the joint at the IPK light. That was how I worked around not using header C0291.

I do not however have a voltage on any of these points. I'm wondering though if the set/accelerate switch on the wheel needs to be pressed before voltage is present? That's what brings my CDTi IPK light on. Having said that, the IPK light here still doesn't come on under any circumstances.

Yes
Yes
Yes

I removed the seat and old brake switch quite easily, connected the new one, and played with the meter before trying to install it. It was a bit of a PITA and I've only gone & forgotten which way round the voltage numbers went:duh: but both pairs of pins (1-3 and 2-4) increased or decreased voltage whenever I moved the tip of the switch close to metal. I'm annoyed I didn't note the numbers but it made good sense at the time. The bad news though is that I gave up trying to refit the new switch after 45 minutes when I decided I'd had enough and really did need to clean the cuts.:rolleyes: I've tricked my motor engineer buddy into abusing his slightly-younger body tomorrow pm so should have it done then. Seems to be working fine though as the brake lights are correctly stuck on now given the switch is dangling under the dash somewhere.

Dougie.

Thank you for your very clear answers Dougie. :bowdown:

Yes, RAVE confirms this.
RAVE also says that the vehicle must be moving under engine power before the cruise control will engage. Could that be the problem; that you're testing it just by turning on the ignition?

Simon

I wish.:( I always take it down the lane to >22mph before checking.

Am I correct then in believing that C0239-11 outputs +12v to the EAT, IPK light and the vacuum pump? I'll check it again in the morning as it's raining now.

Thanks again,

Dougie.

https://www.the75andztclub.co.uk/for...1&d=1593381177

If you were looking at this screen with the car travelling at a speed of >25MPH and then the set accelerate button was pressed, the "cruise inactive" would toggle to cruise active and the cruise symbol would illuminate on the IPK

The cruise ECU will not allow cruise to be enabled before a minimum speed threshold is passed.

Brian :D

But if the state is being reported as Switch 1 Brakes Off/Test Switch Brakes On, wouldn't the IPK cruise symbol remain off? And the same the other way around - Switch 1 Brakes On/Test Switch Brakes Off which is what mine was showing on Jamie's T4? Either of the "brakes on" state would surely cause the IPK light never to illuminate, because braking suspends cruise?

Dougie

Yes.

Simon

Get the new switch fitted and take it out for a drive Dougie, then see what happens ;)

Brian :D

Doing exactly that this afternoon Brian. :} I agree it all points to that.

(Just cos I'm paranoid doesn't mean it's not all a conspiracy though.....:eek:)

Dougie.

Got the brake switch fitted (I did it myself in the end). Cruise still does not function. I've lost the will to live with it tonight so tomorrow I'll run the same checks and see it anything's different. The way I'm feeling tonight, I may disconnect it all and start enjoying the car.

We''ll see what tomorrow brings.

Dougie.

Hi Dougie,

In post no. 6 you said you intended to buy XKB 000 022A. Did you do so? This switch is described in MarinaBrian's EPC screenshot as:
"Manual, petrol, except cruise control".
Your car is automatic, petrol, cruise control.

I would have thought that XKB 000 090 is a better bet. :shrug:
The EPC is ambiguous to say the least.

Simon

Yep, I did despite initially thinking that XKB000090 should be the one. This was because I read two posts where the switches were replaced by XKB000022As. These were KV6s having cruise retrofitted - but they both were pre-wired. That was enough to introduce some doubt to my mind but I went ahead with the 22A anyway. I should have gone with the only switch specified as double pole.

You're not wrong. Brian's screenshot could even contradict itself by also saying "Manual, Cruise Control".:rolleyes:

I may try the XKB000090 tomorrow if that's what it'll take to prove the brake switch's guilt. If that doesn't do it, I'll re-check every damn connection and probably get the snips out if they're not at fault.

Dougie.

OK Dougie, with your new switch fitted and the brake pedal released, are you seeing 0v at:

1. The cruise "relay" C0895-6
2. The EAT ECU C0932-43?

This would prove that brake switch 1 (pins 1&3) is working correctly.

Second question:
Do you have wiring installed from the cruise ECU C0239-7 and C0239-17 to the vacuum pump?

Third question:
Is the cruise ECU receiving a power supply on C0239-1 from the cruise "relay" C0895-9?
I'm asking this since there is no output from the cruise ECU to the vacuum pump, EAT ECU and IPK.

Simon

Conversely, I'm seeing +12v when the pedal is depressed.

.. to C0228-4 and C0228-3 respectively.

...although I can't say definitively it's actually receiving a supply, only that the connection is made correctly.

Dougie.

:} Good, that's what we would expect. However, my question concerned what you see with the pedal released. I've just noticed your rather impressive green ticks which I take to mean "yes", you are seeing 0v with the pedal depressed. That's good.
Ah, that's a pity. We need to establish somehow that the cruise ECU is actually receiving this supply. It appears to depend upon the presence of the enabling signal from the ECM so is crucial.

Simon

I've confused you with green science, sorry. 0v is read with the pedal released i.e. not pressed. +12v is read with the pedal pressed down. That's what I expected - it signals the various ECUs that braking is happening?

That's exactly what I'd expect. Your new brake pedal switch is working correctly.

We need to look at the cruise ECU now because it isn't illuminating the IPK warning light.

Simon

Incidentally, I've again checked the GP wires at C0239-5 and C0895-4 which are connected to (the brake switch) C0775-4. It reads +9v when the brake pedal is depressed and +2.84v when it's released. This is the circuit which signals the LSM to turn on/off the brake lights, which are functioning correctly. Is this in line with your understanding too? I still don't properly understand how the brake light test is handled by the switch, although it was testing ok on T4 and presumably still is.

Subject to the above, that's great.

Dougie.

That's interesting because your original switch read 3.7v when depressed and 11.84 when released; the converse! Of course the switch's Hall sensor circuitry could be entirely different between the two. The main thing is that the brake lights are working correctly. :}
I think "brake light test switch" is purely a label given by T4 so that it means something to a garage mechanic when tracing a fault. It's really a brake pedal position sensor. It doesn't "test" anything. It's a circuit which works in conjunction with the LSM, ABS ECU, cruise "relay" and the cruise ECU to tell them when the brakes are being applied. Does that make more sense?

Simon

I saw that too. I'm hoping I didn't reverse my numbers when reporting early on in the thread!

Yes, understood thanks.:)

I've now tested C0239-1 and C0895-9 at >30mph with cruise switched on, with and without the set/accelerate switch on. No power.

Dougie.

:D Excellent! I think we are closing in on the problem.

So, the cruise "relay" isn't powering the cruise ECU, so what's causing that? There appear to be three possibilities:

• The +12v ignition feed on C0895-8.
• The +12v ignition feed switched by the cruise control master switch on C0895-12.
• The enabling instruction from the ECM on C0895-5. This is described as a "digital signal 0 - 12v". That probably means it's a square wave but your meter should detect whether it's there or not.

The first two can be checked at rest but the third will of course require another test drive.

Incidentally, how did you take the measurements today, using the pin through the wire insulation method?

Simon

I hope you drink. There's a bottle here with your name on it when we crack this. If you don't, I'll have it.:D

I checked the first two earlier this morning. +12v comes from the fuse to a spliced & sealed soldered joint; the two wires then run to C0895-8 and C0749-1 (the master switch). That switch of course is earthed.

On the switched side (C0749-5), that's sending +12v to C0895-12 and C0239-8.

The connection between the two boxes is soldered and sealed midway between them. I stripped back two small lengths of insulation - one on one side of the join and one on the other, to eliminate a dry joint midway - and laid the probe on one and then the other.

Regarding the enabling instruction from the ECM, that was an interesting one. Whilst the ECM is reasonably accessible, it requires removing to access the BU wire at C0371-10 which as you say, runs to C0895-5. I saw that it entered header C0230-5 and was supposed to exit from header C0449-5. I wasn't surprised to find C0449-5 blanked off (230 & 449 resemble round mated trailer sockets in the engine bay). I assumed that as the BU wire was present at C0230-5, it was connected to the ECM but I have to say I've not checked for voltage (although I suppose it would show 0v if it's not activated until 22mph is achieved?). I therefore cut C0230-5 at the header and seal-soldered a feed through the bulkhead direct to C0895-5.

So I need to check the signal to C0895-5 whilst driving?

Dougie.

:party:
Yes. You could, of course, just activate cruise and press 'set'!

Fingers crossed.

Simon

PS I'll be incommunicado for a hour or so soon. Don't think I've lost interest!

There's a +6.26v signal from the ECM to C0895-5 whether or not cruise is switched on. Pressing set makes no difference (it wouldn't, the car was stationary). I didn't drive and test as it involves some shenanigans; I thought I'd have some lunch for a change and await your valued input. ;)

What +6.26v means, I have no clue.:}

Dougie.

Your meter can't read the square wave properly so it gives you an average voltage reading. The actual values will tell us very little. What is important is that the digital signal is now reaching C0895-5.

After lunch please go for a test drive and see if cruise still doesn't work. I'll check-in with you later this afternoon.

Simon

I did with assistance to ensure accurate reporting. Another twist. The +6.26v drops to +0.56v when the car is shifted out of neutral or park into any forward gear. Needless to say, cruise did not work.

Dougie.

Drat and double drat!

I'll have to look at this again either late tonight or tomorrow morning.

Simon

Thanks Simon. I'm about to get my spade out too.

Dougie.

I forgot to ask, did the IPK cruise logo still fail to illuminate?

Simon

Yes, it failed to illuminate.

Dougie.

Hmmm, Wonder if your ZCS codes are configured for Cruise? If you do all original wiring and connectors the ECU says "no" It does not know where to send the signal. :}

The ZCS codes should be configured for cruise as I drove a couple of hours to Jamie's last weekend for that job on his T4. He told me it all configured ok except for the one half of the brake switch, as we've seen. I've run TOAF several times since to check errors, and the three ECUs which I understand need to be told of the cruise existence, do now show cruise on their config displays. That's as far as TOAF goes though.

I've found nothing online referring to cruise control being affected deliberately or otherwise by automatic transmission gear positions. From distant memory though, isn't it the case that if you slip an auto into neutral whilst cruise is engaged, it disengages it? The fact that moving into gear from neutral drops the voltage seems illogical to me but I have no idea how the ECM is designed to talk to the cruise relay, or even if the voltage is supposed to change relative to the transmission state.

I think if we've reached a natural pause in diagnosing, I should revisit and recheck everything I've done. I suppose it's not outside the bounds of possibility that one of the cruise modules is faulty either.

Dougie.

Hi,
Tell me what column 6 in your ZCS SA string reads please .

I will in the morning Stu. Thanks.

Dougie.

Stu, the SA coding in the case of the V6 is only necessary to enable diagnosis to take place with T4, unlike diesel where it is required to make cruise function correctly.

Brian :D

I have in RAVE though. :} The ECM will not provide the cruise control enabling signal (C0371-10) if the transmission is in Park, Neutral or Reverse. That would explain this:
The signal is described as "digital 0 - 12v" which suggests it's a square wave of variable amplitude which is exactly what you're seeing.

But this is still the key question:
Is there still nothing on cruise ECU C0239-1 because 12v should be provided there by the cruise "relay" when it receives the enabling signal on C0895-5.

Simon

I need to dig deeper into RAVE, clearly.

Presumably then C0895-9 feeds C0239-1 and should also show 12v. I'll check it all again shortly.

Is this level of detail from RAVE too? I've only ever used it for the wiring diagrams.:rolleyes:

EDIT: I've answered my own question. "Description and Operation" was the clue.:D

Yes, when the enabling signal is present.

Awaiting the result! :drool4:

Simon

There is virtually no voltage at C0895-9 under any conditions (virtually = +0.01v). The ECM signal is working in line with the P/R/N restriction as before at C0895-5. So apparently the interface/relay isn't outputting 12v when it should be.

Dougie.

OK, before condemning anything let's make sure that the interface ECU (aka cruise "relay") is getting all the supplies and data it needs.

Pin 1: earth
Pin 2: not used
Pin 3: not used
Pin 4: variable voltage input from brake switch Hall sensor (C0075-4) Yes (post 56)
Pin 5: cruise control enabling square wave signal from ECM (C0371-10) Yes
Pin 6: 12v input from brake switch (C0075-3) Yes
Pin 7: road speed square wave signal input from ABS ECU
Pin 8: +12v ignition supply Yes
Pin 9: switched +12v supply to cruise ECU (C0239-1) No
Pin 10: road speed square wave signal output to cruise ECU (C0239-15)
Pin 11: input from clutch switch Is this pin empty?
Pin 12: +12v input from cruise master on/off switch. Yes

Simon

Pin 1: earth Yes
Pin 2: (not used)
Pin 3: (not used)
Pin 4: variable voltage input from brake switch Hall sensor (C0075-4) Yes
Pin 5: cruise control enabling square wave signal from ECM (C0371-10) Yes
Pin 6: 12v input from brake switch (C0075-3) Yes
Pin 7: road speed square wave signal input from ABS ECU Yes, +12v, stationary check
Pin 8: +12v ignition supply Yes
Pin 9: switched +12v supply to cruise ECU (C0239-1) No
Pin 10: road speed square wave signal output to cruise ECU (C0239-15) Yes, +11.3v when cruise switched on, 0v when off, stationary check
Pin 11: input from clutch switch Pin and tail present, not connected
Pin 12: +12v input from cruise master on/off switch. Yes

All answers have been double-checked.

Dougie.

Just so you know, the codes are below (with checksums)

713601117
218048C18108024A3
0400000041K

As Brian has said, V6 cruise works without coding, you just can't run diagnostics on it.

Cruise is enabled with those codes anyway.
Number 8 colour in red.

So I'm out :getmecoat::getmecoat::shrug:

This is what I would do next Dougie. I'd break your new connection from the interface ECU C0895-9 to the cruise ECU C0239-1. I'd then supply C0239-1 directly with +12v to see if the cruise ECU will then reward me for providing it with a power supply.

What do you think?

Simon

I'll tell you what I think Simon. I think if I was 40 years younger, I'd marry you & have your babies.:lovebirds: :D:D

It only bl00dy works!! Engages and disengages when it should (road speed, gears, brakes), the IPK light is fine, and because I mounted the vacuum pump on the right-side bulkhead, I can hear it BRRRP when it does its thing (I thought it was the ABS to start with & panicked a little :})

So I guess the cruise relay needs to be condemned after all? If so, no big shakes there.

I really could not have done it without your reasoned input and systematic diagnosing, Simon. It's been a complete bu99er but also a really good learning experience. I'm glad in the end that my wiring was fine, although I would've been equally glad to admit errors to solve the problem. I'm a great believer in paying things forward, so maybe I'll be able to advise some poor bloke struggling with his KV6 cruise retrofit, to not bother.:D

Dougie.

:laughing2:
You've got a great sense of humour Dougie!
Well it's a bit odd. From where did you get the cruise "relay"?
Edit: Surely the absence of the Shift Interlock ECU couldn't be responsible?
Thank you very much Dougie. Not everyone judges my methods that way. You're a gentleman.

Simon

Just as well, eh? :rolleyes:

eBay, as part of a "retrofit kit" (pump, throttle body & actuator, ECU, interface, paddle switches, master switch and - oddly - an EAT module which I didn't need). They were all quite tatty & showing signs of lying around in a damp environment.

There's one on eBay about 30 minutes from me for around a tenner so I'll have it and see how it performs. I now need to stop myself thinking ahead ("What happens if that doesn't work.."), although just because I'm paranoid doesn't mean my cruise control isn't jinxed....

Dougie.

https://www.the75andztclub.co.uk/for...e0ed8a61c9.jpg

I just spotted your edit about the shift interlock. I was wrong about that - it is there although it doesn't require the brake switch's input.

What harm might be done to leave it wired the way I did it today as the workaround?

Dougie.

:wot:
I've just checked my car and you're right.
Provided that you've used a +12v ignition feed then possibly none.

The only remaining possible explanation is this from RAVE:
"The interface ECU monitors the two inputs it receives from the brake switch and checks them for plausibility. If the two inputs differ, the interface ECU disconnects the power supply output to the cruise control ECU to cancel/prevent cruise control operation for the remainder of the ignition cycle."

Maybe the brake pedal switch still isn't what the interface ECU is expecting?
:shrug:

Simon

I can see that that's a possibility, in which case, that fail-safe function provided by the interface ECU will be bypassed. C0239-5 on the ECU will continue to monitor the brake operation from the LSM side of the switch (C0775-4) and go into suspend mode as it should (and does). It will depend solely on the brake light circuit for braking disconnection; on the other hand, if (e.g.) the switch fails, the LSM treats it as if the pedal is depressed, and so will the cruise ECU.

On balance, I'm still doubting the replacement brake switch not being the 100% correct one. We'll see though. (I'd far rather try changing the module in 15 seconds of comfort than draw more blood and bruises changing the brake switch yet again!!!). I didn't mention that the replacement I got from Rimmers had a manufacturing fault (one of the retaining clips on the holder was missing) which wasn't spotted until my mate took it out the bag to fit. I had to return to Rimmers to exchange it which wrote the day off and meant I ended up fitting it myself!! See - it is a conspiracy.

Dougie.

What about the brake pedal status switch: C0075-3 to C0895-6? The quote from RAVE mentions both.
So am I. But that's not the fault of any contributor to this thread. The EPC descriptions are nonsensical. Since your brake lights work and so does cruise, there's a case for cutting your losses and supplying the cruise ECU independently of the interface ECU.

Simon

Good point, well presented.:eek: That was my bad - I misread pin 4 for pin 3 on C0775.
Oh absolutely!
We'll know soon enough when I fit the new interface tomorrow. There's no guarantee that doing yet another brake switch replacement will resolve it either, and so long as the car doesn't go on fire and the cruise control goes off when I brake, I'll be happy.

Dougie.

PS: Any comments from firefighters and/or electronics engineers are welcome. Undertakers need not apply.

bundle
 

looks like from your photo you have the landrover cruise ecu not the OO190 valeo version. there are a couple of versions on the bay now. maybe they are the same pinouts or maybe not ... :shrug: just a thought.....

The 100190 you refer to is the cruise ECU and that's what I've got. It's the cruise interface (or "relay") SCB100201 which is not operating as it should. That's also common to Landys and MGR.

Dougie.

https://www.the75andztclub.co.uk/for...e6329000d4.jpg

ah ok. just a thought . been following the thread... enjoyed it !! the scb100190 is a hella i think not a valeo as i previously said. maybe its the pump thats valeo. glad its almost sorted. well worth it i think as from what i have seen of the car from the pictures shes a beauty. .... regards xsport ;)

I appreciate the thoughts.:) Nice to be reminded how great the car is too after this job. She drives, feels and smells like a new motor and so she should with only 28k on the clock. Once this lot's tidied away, I shall be mindlessly applying some quality wax with a stupid grin on my face, and maybe a beer. :D Cheers.

Dougie.

Diagram correction
 

Now that the investigation is drawing to a close, it's worth noting that the labels for the two halves of the brake switch are incorrect in the above drawing.

MarinaBrian's T4 screenshots (post no. 31) tell us that the correct labelling is:

• Pins 1 & 3 = Brake switch 1
• Pins 2 & 4 = Brake light test switch (switch 2)

Simon

i have the rover 75 kv6 2.5 auto with cruise. 2001 year. mine had the original brake switch from new (dont have details as i discarded it) when my brake switch packed up last year i needed a replacement and looked at past threads and was told the xkb000022A was the only one that works now on the autos. that switch i was told would also work on the manuals. xkb000022 was only for the manual brake and clutch. whatever the truth is it worked for me no problems. same cruise and interface parts i presume. no doubt you will eventually find the right combination if not..... happy hunting !

I collected the replacement SCB100201 cruise interface this morning and fitted it after disconnecting the bypass wiring I successfully tried yesterday at message #82 above. There is still no voltage on C0895-9, so obviously the interface is inhibiting the 12v output to the ECU due to another element. The brake switch remains the chief suspect as previously discussed.

I removed the non-working C0895-9 feed to C0239-1 and instead of connecting a spurious 12v feed to C0239-1 as I did yesterday, I used the master switch C0749-5 output as it made sense to control everything from the same switch. Alas, instead of the IPK light coming on and cruise working as before, when I pressed the set/accelerate paddle, it flashed once and the horn sounded. Thereafter, it was dead until I stopped, switched off the engine & restarted when it repeated that behaviour.

I removed the C0749-5 supply and reconnected the separate feed to C0239-1 as per yesterday. Everything worked again. Tried the switched feed one more time but just got the flash 'n' toot followed by nothingness (presumably because the ECU errored out and did what it's supposed to do until it's restarted and cleared).

The correct thing to do would be for me buy a XKB000090 brake switch and try that as it remains the only one which is specified as double pole. After weighing up the risks, disadvantages and advantages, I am not going to do so and will instead complete the wiring with the separate feed to the ECU C0239-1. I would though like to know why the cruise master switch connection produces an error as I want to have only one switch. I can work around it using a relay if necessary.

Was your car built with the wiring in place?

Dougie.

yes it was. just been on rimmers and they list a brake switch blue XKB000090 with the application as for cruise control but with the caveat of serial numbers from 5d345692 CP type - vin. onwards . other than that theres just the normal XKB000022A. i bet you are not relishing that brake light switch change :duh: but if your vin is in that group it could well be the one you need . :shrug:

Your wiring will have been different to mine then, which was wired completely without any cruise elements including some headers.

Mine is prior to that but I'm sure the blue 090 would work with my reconfiguration, possibly even ironing out the last issue.

Well indeed I'm not because I'm not changing it.:D

Dougie.

dont blame you for that ! i left my seat in and draped my legs up and over the top (without headrest of course ) in the back and shoulders to the floor configuration as it were . just thinking are you sure that the interlock is not a pre requisit check before the engine ecu will deliver the 12v required along with the abs signal ? who knows . also you must have got the plugs for the interface and cruise ecu with the bundle. did it have the tails and you hardwired onto them ? have you double checked that 12v from the engine ecu is actually getting through at the pins.you could recheck against the readings on the other plugs to compare. it wouldnt take much for it to drop below with a not too good contact may be it needs pretty much the full wack to trigger the cruise (safety reasons) ? cant see you having 2 faulty units . i had a similar problem once to green buildup on a door plug once although i couldnt see a problem visually checking. sometimes we overlook the obvious but im not trying to be disrespectfull in any way as i can tell that you are more than competent. .. just trying to save your knuckle joints from more abrasion !!! :D

Yes we have Stefan, see post 79. :}

Simon

What you effectively did there Dougie was to connect the cruise ECU C0239-1 and C0239-8 pins together. I wonder if placing a diode between them would solve the problem?

You could use C0749-1 instead. That's the supply to the master switch but C0749-1 will be live only when the engine is running which is effectively the experimental state you have at the moment. However this might not work either because you'd then have C0895-8 and C0239-1 connected together! :o

Simon

was the reading sufficient simon ? it all seams a little bewildering as to why it does not function.especially after changing of the interface as all the data requirements are there ... but are they in the right quantities ? or is something missing. have you ever known a kv6 180 sport auto without interlock ? there must have been a header in there at some point as dougie refers to a plug type fixing in there resembling a towing electrics plug affair. the header must have been removed unless a bespoke loom was made to order at assembly ... which i doubt very much. i cant see any towbar at the rear from the pictures and doubt if the interlock would have been removed for towing .. thats dangerous.! i wonder if the interlock circuit is incorporated with the cruise circuit at all. it may be possibly. what do you think simon ?

According to Rave, MGR discontinued fitting interlocks except for a few overseas markets. In these cases, a solenoid is fitted at the bottom of the gear lever which prevents the lever being moved from Park unless the ignition switch is in position 2 and the foot brake is applied. My car does have an interlock but it's not connected to the brake. I don't know what it actually brings to the party though. A header has definitely not been removed - the wiring loom is virginal. It's just not there because it was only used for cars with cruise, parking sensors and the brake application of the shift interlock fitted.

Incidentally, the mated headers in the engine bay resembling towing electrics plugs, are still only headers albeit different shapes to the normal oblong ones. The only connection of interest to the project has been the digital signal from the ECM to the cruise interface saying "ok, I'm configured for you" which was only partially fitted in the factory. I had to extend it from where it had been capped off to the cruise interface.

According to the diagrams, it is connected (somewhere) to the auto transmission (C0932-43). The cruise interface also connects to that pin, but both are inputs to the EAT.

The signal from the engine ECM is a digital variable square-wave voltage between 0-12v. It's not a standard +12v supply. That signal is getting through (it's specified in post #79 above).

Yes, most likely. I'd thought of using a SPST relay triggered by C0749-5 and making a supply (maybe spliced from fuse 41 which supplies the entire cruise system) to C0239-1? Do you think it still might be susceptible though? A diode would certainly clean it up.

I didn't like the thought of a common connection there either.

Dougie.

According to the wiring diagram there's no interconnection between the cruise control and the shift interlock ECU.
My 75 is very early, built in May 1999, and there's no interlock either with the ignition switch or the brake pedal, so maybe I don't have the interlock ECU. :shrug:

Wouldn't that also connect C0895-8 to C0239-1 (which you've already tried when the master switch is closed)?

Simon

I'm sure the interlock has no bearing on the issue. I'm still not sure I have one - there's an ECU bolted to the bottom of the driver's side A pillar where they were fitted but I can't see what it is without removing it. I've no intention of doing so unless I have to!

Well would it any more than using the experimental supply? I mean, everything ultimately is powered from the same source in the end. I obviously understand there is an issue with powering directly from the feed i.e. C0749-5 but I don't know the cause of it (do you?). My reasoning for the relay idea was that if C0749-5 was used only to activate the coil, it's such a low current that it shouldn't give a problem. The power source to C0239-1 activated through the relay can come from any suitable fused source.

My reasoning though is based on incomplete knowledge of what's causing the problem, so I can't know if that's feasible.:shrug: A diode on the other hand is a one-way street and would provide the solution from the existing master switch. I guess I know which way I'm going.:D I have used Schottky diodes successfully before on projects. Their power drop is lower than standard diodes and they have faster switching speeds.

Dougie.

Simon,

One VIS motor is currently away at Stocktake's for repair so I've not been able to try out the diode yet. It's connected and awaiting the test though.

Do you know the reason why the ECU doesn't like sharing the same switch with the interface? I'd like to understand it.

I've reassembled the car's interior and apart from the radio still being out to let me finalise the switching, it looks tidy again. :)

Dougie.

No, I don't Dougie. No-one does. It depends upon the circuitry which lurks behind the two connections on the cruise ECU and upon what's happening in the interface unit. It's certain to be complex and protected by corporate confidentiality.

Simon

So I fitted the diode between the master switch feed C0749-5 and the cruise ECU C0239-1 to see if that eliminated the electronic brain f@rt which occurred when the set/accelerate button was pressed (horn tooted/IPK cruise light flashed as per post #97). It still didn't like it. The ECU is therefore powered by its very own fused 12v ignition-controlled supply as I could not be bothered to pursue the matter any further. Choose your hills on which to die, I say. :)

I did a 20-mile cruise test this afternoon after adjusting the throttle cable to take up slack which seemed to me to be causing a small pick-up delay when the vacuum pump kicked in (it was). It's perfect.:drool4::clap:

It's been a challenge but glad I did it. Couldn't have done it with the forum though. Thanks for everyone's input.

Dougie.