[prhim]

I had the untimely - not to say somewhat embarrassing - misfortune to have my car go into 'limp home' mode last Friday.

Basically the dashboard lit up like a Christmas tree, with Handbrake Failure, ESP Failure and Heating Coil (or whatever the diesel fuel heater thingies are called) symbols all appearing at the same time.

Pulling away, it felt like the car had 5bhp, not 240 odd and the exhaust sounded very strange indeed...

Needless to say I pulled over and called Audi Assistance. An hour or so later, the chappy arrived (Sean, very nice guy) and plugged in. From what he could tell at the roadside (in fact, a Sainsbury's car park), the ECU had detected a fleeting 0.5 volt drop in battery output, which was enough to put the whole car into 'safe mode', effectively turning off all 'non-essential' systems.

While Sean was able to re-set most of the alarms and faults - the ECU alert had even caused the aircon to have a hissy fit - he couldn't reset the ECU main fault, as apparently this can only be done when the car is directly 'dialled-in' to the factory, which can't be done roadside (RAC obviously hasn't invested in mobile broadband!).

Anyway, car was now driveable, so we took a 15 minute ride to local Audi dealer where the car was hooked up on the 'proper' kit.

To cut a long story short - another ECU patch was applied, which I am assured will stop the problem happening again. But even the dealer staff had to agree it was ridiculous for such a little problem to have caused the car to effectively shut down.

Anyway, a wasted three hours all in all, but at least the car is running again...

..but of course now I need to make another visit to Essessive as all the DRL mods were over-written and now I've got those bloody winking DRLs again...!

grrr.

 

[Shane]

That is suprising. I wouldn't have thought such a small thing would cause such a headache. I am laughing at your blinking lights though. It seems everyone hates those. I plan on getting mine "fixed" once I get home.

 

[cburkard]

Ah, limp home... I remember that in my V10 TDI Touareg and it does suck. Hope they can isolate the cause quickly. Took about two months to find a faulty OnStar module in the Touareg.

 

[Rab88]

A 0.5V drop caused this?

Did you find out what the reading was on the battery?

 

[prhim]

I seem to recall (but could be wrong) it was about 12.5V

 

[RGBArgee]

Is it possible that your 'mods' might have caused the original problem. I'm not an auto electrician by any means but had a similar problem with a Saab Aero a few years ago when using a 'non-Saab' replacement for a blown bulb. If your mods are the problem Audi/RAC seem to have been pretty good sorting for you.

 

[Deepmeister]

Is it possible that your 'mods' might have caused the original problem. I'm not an auto electrician by any means but had a similar problem with a Saab Aero a few years ago when using a 'non-Saab' replacement for a blown bulb. If your mods are the problem Audi/RAC seem to have been pretty good sorting for you.

DRL mods via VAG-COM are extremely unlikely to cause a problem, if at all. The car "knows" about it since it is simply a setting in the CPU. Anything that relies on voltage levels is also unlikely to be triggered by the DRL brightness level, the difference in current drawn is too negligible especially if the engine is on and the alternator is functioning correctly. As it happens, the DRLs only come on when the ignition is on. Even still, a 0.5v drop should not be an issue especially if it running at 12.5v anyway. Standard running voltage tends to be around 13.8v but anything above 12v but below 13.8v is still within specification for a 12v electrical system!

Thats said, any "physical" change like replacement bulbs of different specification, or bypassing the 12v cigar lighter socket and accessing circuitry directly behind the dash could have an impact, but again unlikely for "normal" current consuming devices like cellphone charger leads or radar leads which are simply drawing a 12v supply at low current - unless you tapped the wrong wire by mistake where it may have 12v on it, but is not a feed circuit. If you made any physical mods, that would be the first place to look for a fault. If the fault is due to a physical mod, there is a good chance Audi will not consider it as a warrantly claim.