Dead Zed!

[grendel]

So, just a week after it's 13th Birthday, my ZT died on me tonight.

I've had a strange phenomenon the last couple of months or so; occasionally when I've gone to start up the car, as the key has reached the auxiliary position, the heater fan has been blowing full blast, despite only being set at level 2 or 3. This happens for a few seconds then reduces to the set speed as I start the engine. This doesn't happen all of the time, maybe once or twice a week.

This evening, however, after leaving work, I turned the key to the aux position, the heater fan started blowing full speed, though this time I noticed the heater panel display was off (though I'd left it on when I left the car earlier) Instead of it reducing speed when I started up the fan carried on blowing. The engine then cut out after about 5 seconds. I noticed that the yellow engine warning light hadn't gone out at all during this whole process.
Anyway, I turned the engine off & restarted, and everything was fine, heater fan normal, & all the relevant lights either on or off on the dash display.
So, I drove home via a detour to the supermarket. As I stopped to drop the car into reverse to park, the engine cut out and wouldn't start again. The dash display at this time had gone out, no lights at all, likewise no display on the heater control panel, and all the dials on the dash were dead. The Message Centre display, however, is working fine. The engine cranks over as normal but won't fire up. All of the auxiliary systems are working (lights, wipers, indicators, central locking etc) but not the heater control. Even the cigarette lighter is OK.
AA came out & couldn't find a fault, though there obviously is one somewhere. Fuses & relays checked & all OK, the car just won't fire up.

A call to Dr Lates is imminent, but just after a few pointers, you never know, it may be something stupidly simple! :shrug:

[rich17865]

Sounds like water in something to me.

Or maybe an aftermarket radio causing trouble.

[grendel]

Doubt it's the radio as it's been in the car almost as long as I've owned it (11 years) and it's never been an issue. As I said, the heater fan thing has been just the last couple of months, just wondering the whether it's linked to the ignition problem or just coincidence.

Water? Maybe, maybe not. Used to have a water ingress issue from sunroof drains but that's been cured (fingers crossed), certainly no evidence of water inside the car, at least not in places I can see & feel

[rich17865]

High line sat nav?

Have you tried unplugging the air con panel? It could have gone faulty amd be causing trouble, rare, but possible.

[grendel]

No Satnav Rich, but no, not tried unplugging aircon panel. May be something worth trying when I get 10 minutes.

[The Mighty Quinn]

Sorry for pointing out the most obvious thing going, but have you checked the plenums?
I did on mine at the weekend and a good thing too, as several inches of water had gathered in there - and only a month or so since I last checked them.
If it got to splashing up around the ecu, maybe it could have the effects you describe?

[Greeners]

Unlikely to be the plenum unless it's over flowed onto the BCU and passenger fuse box. The V6 ECU is vey well sealed unlike the diesel one.

I would try reseating the ATC panel (both connectors on the back), if that makes no difference, it may be a K-bus fault,

[rich17865]

Do you have parking sensors, is it a saloon?

[grendel]

Yes to both questions Rich. In case you're wondering, parking sensors working fine, as are all of the other electrical accessories/auxiliary circuits. Just a dead AC panel & engine

[rich17865]

Pull the boot liner back as if changing a bulb, unplug the parking sensor ecu and check again.

The rear windscreen trim clips can leak, the water can drip straight into the parking sensor ecu and cause k bus problems much like what you describe.

Certainly worth a look.

[grendel]

I'll give it a look Rich but I regularly check for water in the car after sunroof drain issues (now resolved) & a leaky rear light seal caused a lake in the spare wheel well. In fact I had to go into the well tonight to get the towing eye & there was no sign of dampness there, if the rear window was letting in water surely it'd reach the wheel well/boot carpet if left long enough?

[rich17865]

Yes, if left long enough, but it only takes a couple of drops to make a connection between the bus wire and another.

Might be dry, but worth a look as it is easy and nil cost :)

[marinabrian]

I reckon the EWS3 immobiliser has finally succumbed to water drooling into it from the sunroof drains.

I'm sure Lates will find the fault though, definitely K-Bus related though ;)

Brian :D

[grendel]

I reckon the EWS3 immobiliser has finally succumbed to water drooling into it from the sunroof drains.

I'm sure Lates will find the fault though, definitely K-Bus related though ;)

Brian :D

But would that cause the aircon control panel to die, as well as the dials/lights on the dash? As stated, everything electrical seems to be working with the key in aux position, trip meter & message centre all working too.

Quick update regarding Rich's suggestion about the parking sensor ECU. Thought about it today & recalled that the engine died just as I'd dropped it into reverse to park, so tonight I thought I'd just try turning the key & engaging reverse to see if the parking sensor activated (as it normally would), it didn't, coincidentally. Couldn't see if the reverse lights were on or not to be sure the reverse switch had engaged but certainly no sensor beep, so quite possibly a problem there. Unfortunately, due to the way I've had to "park" the car in the parking bay, I can't get access to the boot to check ECU (pushed right up against the bushes behind), the car is a bit heavy to push up a slight gradient on my own so need a bit of help moving it first :D

Finally, sounding a bit uninformed, lots of suggestions of K-Bus fault so, what is K-Bus, where is it and would it be a simple fix, or is it something serious?

[rich17865]

K bus is the communication line for all of the cars ecu's to talk to each other. If it gets cut or shorted out in some way it can be curtains for many things.

Yes a tiny fault on the bus line can result in many things failing.

[grendel]

K bus is the communication line for all of the cars ecu's to talk to each other. If it gets cut or shorted out in some way it can be curtains for many things.

Yes a tiny fault on the bus line can result in many things failing.

And would any such fault be picked up by a diagnostics check and pinpointed as to the exact area of the fault, or is it more a process of elimination?

[rich17865]

Nope, because there is a communication problem, it will be impossible for anything to talk to the car.

[grendel]

Thanks for all of the advice & theories guys, checked & tried most of all the suggestions but had no joy, Lates & Pete had me checking fuses & fuse links, earth connections etc (dozens of text messages going back & forth!), but still had nothing.

Ended up paying to get the car transported to Lates Sunday afternoon. After half hour of fiddling about Pete came across the problem, something as simple as the ignition switch! All the signs were there, no life in the dials or instruments, no headlights/reverse lights,aircon panel; basically everything that works in the aux position on the key failed. However, because you could still turn the key to crank the engine, it never dawned on me it could have been that simple :duh:

Anyway, car now in the hands of the good Dr Lates, awaiting parts & repair.
As I said, it's something simple or serious....