Catastrophic electronics failure?

[TriggerFish]

Morning all, a pretty bad start to the week so far!

So I was driving, with some speed, down the back roads to uni when first the battery followed quickly by the ABS and brake system lights came on and the car started shouting at me. I pulled over into a gate/field, conveniently next to a police car. At this time, the brakes were still working. I got out, checked the fluid level; perfect, checked all the hoses etc where I'd upgraded them; fine - secure and dry. Not sure what the fault was, and given I was about 1/2 mile away from uni, the policeman gave me and escort there so I could park the car safely and get it checked out.

On the way there the warning lights kept coming and going randomly, but as I drove other lights on the dash started coming on/off, ECP, airbag, battery (fuel light should have been on, but wasn't). The car still seemed to drive fine, but I didn't get speed up incase the brake fault was real! When I stopped at uni, I noticed the aircon didn't work at all, the fan just wouldn't spin up. I've disconnected the battery and left it parked up. Will hopefully get it VAGCOM'd if I can find someone with a laptop, but guessing I won't be able to fix it instantly.

Anyone come across anything like this before? I was wondering if the battery light being the first is hinting at low voltage causing the issue? It started perfectly when I tried to drive to uni though. . .

Guessing I'm going to get the car recovered by the RAC as I don't want it cutting out on me half way home etc.

Joe.

[joe2612]

OO er doesn't sound too healthy. I would hold any action until you can diagnose with vagcom. Because it sounds electrical vagcom should give you a pretty good indication.

[TriggerFish]

Well, I got hold of a laptop (thanks Mike!) and got it scanned. Also found some results from normal troubleshooting.

With the ignition on, the AC works. Start the engine it stops. The only HVAC fault code that's relevant is a voltage (too high I think) one.
If I go into the other modules, there's nothing new there except, but most of them are reporting that the voltage is either too high, or too low. If I clear the codes it's fine until I start the engine, then they return again. Something else worth noting is that VAGCOM kept throwing up 'too many communication errors to continue' messages.

To me, that suggests that something is causing the voltages to exceed spec when the engine is running - I think this can be checked with the climatronic screen, so will try that later, although if not I also have a multimeter in the car too. Does anyone know the 'in range' values the alternator should be outputting off-hand?

In terms of what's caused it, the only thing I've changed recently is the addition of 3 LEDs/ambient lighting in the doorcards, but I'd be amazed if they're causing this.

On the positive, if it is alternator etc related, then I'll be grateful it's not a bigger fault within the depths of the electronics of the car. Had that on the Golf and never fixed it!

Assuming I can't get to bottom of it, I'll be making use of my RAC cover!

[rover220]

dead alternator, check voltages with engine on and off.

sisters boyfriends did pretty much exactly as you describe and i fitted a new alty and all was well.

[rover220]

when running anywhere between 13.5v to 14.4v is considered normal

[TriggerFish]

Awesome - thanks!

Will go and check later on!

Would kinda make sense thinking about it as something down around that part of the engine has had a supercharger-esque whine for a while now. It's been doing it for 18months with no ill-effect so never looked into it.

[joe2612]

Well, I got hold of a laptop (thanks Mike!) and got it scanned. Also found some results from normal troubleshooting.

With the ignition on, the AC works. Start the engine it stops. The only HVAC fault code that's relevant is a voltage (too high I think) one.
If I go into the other modules, there's nothing new there except, but most of them are reporting that the voltage is either too high, or too low. If I clear the codes it's fine until I start the engine, then they return again. Something else worth noting is that VAGCOM kept throwing up 'too many communication errors to continue' messages.

To me, that suggests that something is causing the voltages to exceed spec when the engine is running - I think this can be checked with the climatronic screen, so will try that later, although if not I also have a multimeter in the car too. Does anyone know the 'in range' values the alternator should be outputting off-hand?

In terms of what's caused it, the only thing I've changed recently is the addition of 3 LEDs/ambient lighting in the doorcards, but I'd be amazed if they're causing this.

On the positive, if it is alternator etc related, then I'll be grateful it's not a bigger fault within the depths of the electronics of the car. Had that on the Golf and never fixed it!

Assuming I can't get to bottom of it, I'll be making use of my RAC cover!

First of all, The AC will only work when the engine is on as it runs of thew aux belt.

'Too many comms errors' is a fult with the laptop COM ports you are using i believe, try a different USB port.

It sounds like a possible earthing issue- have you checked your main earth?

[joe2612]

P.s i have a spare alternator if required..

[TriggerFish]

Sorry, I meant the HVAC fan (the one used for heating too) doesn't work when the engine starts, but does with just the ignition, not the aircon compressor itself.

I went out at lunch and was ready to have a poke around. Started the car to show someone else the problem and it was fine. Went for a quick drive and all was well.

Really not sure what the issue is/was, but I'll be keeping an eye on it, but for now it seems fine.

Had a look at the cost of a new alternator on ECP - £170ish for a BOSCH part!

[joe2612]

Hmm sounds more and more like an earth issue....

[rover220]

Deffo dying alty. It will happen again. I can get you a recon using bosch parts for £110 plus yours in return.

[TriggerFish]

Well, I don't need the car again until this time next week, I can get around with out it so I'll wait 'til the weekend and check all the earths/free bits before I spend any money on bits.

Thanks,
Joe

[TriggerFish]

Famous last words! The AA are on their way!

[rover220]

Diode pack or regulator will have died.

Vags are super sensitive to voltage fluctuations hence the warning lights and electrical items playing up.