Wiring diagram - advice please (photos)

[SKS Disco]

Originally Posted by goltho

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 .

[goltho]

Originally Posted by SKS Disco

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

I will in the morning Stu. Thanks.

Dougie.

[marinabrian]

Originally Posted by SKS Disco

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.

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

[SD1too]

Originally Posted by goltho

I've found nothing online referring to cruise control being affected deliberately or otherwise by automatic transmission gear positions.

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:

Originally Posted by goltho

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.

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:

Originally Posted by goltho

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.

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

[goltho]

Originally Posted by SD1too

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

I need to dig deeper into RAVE, clearly.

Originally Posted by SD1too

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.

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.

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

[SD1too]

Originally Posted by goltho

Presumably then C0895-9 feeds C0239-1 and should also show 12v.

Yes, when the enabling signal is present.

Awaiting the result!

Simon

[goltho]

Originally Posted by SD1too

Awaiting the result!

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.

[SD1too]

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

[goltho]

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.

[Jamiewelch]

Originally Posted by SKS Disco

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

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.