MOAR Audi electrical problems!!

[Lankytim]

Following on from my recent indicator/hazard electrical disaster I now have a new problem which I'm having difficulty getting to the bottom of!

 

For starters the fuel/temp gauge no longer work, along with the reversing lights- annoying. On top of that the battery does not seem to be charging. The battery symbol does not illuminate on the dash either when the ignition is on or when the engine running (a couple of days ago it came on and flickered a bit before going out whilst driving).

 

I put a fresh battery on last night and it started fine this morning, however I went out to it at lunch time and the battery was stone dead, it could have gone flat in the 7 miles or so it takes to get me to work.

 

I have had the instrument binnacle out again to see i'f I have left any wires disconnected but everything looks fine, all the fuses check out too.

 

The Audi had its exhaust welded a week ago if that makes any difference- maybe something electrical was fried.. Dunno! I hate car electrics!!11!

 

Any suggestions before I ring an auto electrician, mess about with it for a few months and eventually scrap it?

[Rocket88]

If he didn't disconnect the battery whilst welding, he could have bollocksed Gawd knows what. I'd strap a voltmeter across the battery when it's running, you're looking for 14.2 volts [ish] if not, alternator may be fried.

[Richard]

I think your welder chap has disconnected the battery negative lead as recommended but left something off, or not secured it properly when he was putting it back. I had similar symptoms on my Sunbeam when the earth strap between the engine and body worked loose. Also, some alternators are rubber mounted and require an earth wire, these can break and give you problems.

 

If you don't have a multimeter you should buy one, the cheapo £4 ones are sufficient for this sort of work and it makes a big difference knowing how many volts you've got.

[Lankytim]

With the engine running the voltage across the battery terminals is less than 12v, my multimeter doesn't have the facility to tell me exactly what the voltage is though.The voltage from the live terminal on the alternator is more than 12V, but again, I don't know exactly what it is.

 

None of this explains the lack of lights and gauges on the dash, though!

 

Nothing was disconnected for welding, BTW.

[Richard]

If you've got more volts at the alternator than at the battery I'd say it's very likely to be an earthing problem. Connect a jump lead between the battery negative terminal and the engine, see if that makes any difference.

[Owain-328i]

Unusual for a kraut to suffer electrical woe's.

 

Earth problem, or as said something has been fried by the battery not being disconnected during welding.

[Lankytim]

It starts fine with a good battery though, so the engine earth must be OK....

[Mr_Bo11ox]

I think your alternator is bolloxed, if you're getting 12v or less with it running its defo not charging. You need to sort that then evaluate what other problems you've got, as low battery voltage (due to the goosed alternator) can throw up all sorts of spurious symptoms.

[Lankytim]

I have a spare alternator in the garage, it worked fine when It was removed from a breaker a few years ago! Ill wang that on and see what happens. Unfortunately the pulley needs swapping too and they can be a bastard to get off making it a "weekend in the garage scraping knuckles" job rather than a "15 mins during the lunch hour" one.

 

This may sound a bit daft, but is there a fuse or relay that controls the alternator charge? I was messing about with the relays in the drivers footwell while trying to find the flasher relay the other day- theres always the possibility that I did not put one back in the right slot or something.

[Richard]

Does the alternator have a thing that looks a bit like this on the back?

 

 

If it does you can just change that. It's two screws and you usually don't even have to remove the alternator. Try the one from your spare alternator and see if it helps.

[Lankytim]

Already done that! The original one was badly worn with one brush much more worn down than the other. The one on the spare alternator looks pretty much brand new, wanged it on- no difference

[Richard]

That's the only bit of your alternator that the welder could blow, so I wouldn't bother changing the whole unit.

 

I still think the power isn't finding its way from the alternator to the battery somehow. The battery + terminal should have the same voltage as the alternator output.

[M'coli]

It starts fine with a good battery though, so the engine earth must be OK....

Could it be a live problem? Is it possible that the main charging wire has become damaged or the live feed to the field windings has been disrupted? Can a live feed with a bulb be attached from the +ve of the battery to the alternator to check this out in some way?

[Lankytim]

I dunno, i'm at a dead loss ATM!

 

A nice fella on RR has suggested that the flexible circuit thingy on the back of the instrument cluster could have been damaged by constant removal and refitting. The alternator needs a live feed from the battery warning light in the cluster, if thats not there the alternator wont charge the battery.

[daverapid]

Apart from obvious stuff like battery connections and earths I'd be looking at the ignition switch, ignition relay [if there is one] and associated connections.

[Rocket88]

Nothing was disconnected for welding, BTW.

 

 

I'd be having a serious word with your welding bloke if I was you.............

[Lankytim]

Well I was working on the car with him at the time, so i'm partly to blame!

 

To be fair the fault did not appear until a few days later when i'd started taking things to bits trying to fix the hazard lights. I'm laying the blame for this particular problem directly at my own feet as it deffo seems that its something i've done thats caused it.

[Lankytim]

Ok,

 

The battery now seems to be charging, although all the other problems remaim so the car is drivable ATM

 

Strange things are happening though, after 5 miles or so the battery symbol lights up very dimly and the temp and fuel gauges come back to life, although they only register half of what they should do, the handbrake light also works, again very dimly. When I turn the ignition off and then back on again its back to square one with nothing working again.

 

Weird- anyone know a good auto electritian!

[M'coli]

This seems like the old mk2 Cavalier problem, whereby the battery light wouldn't glow, the fuel and temperature guages wouldn't work, but if I revved the car to 5k or so, the alternator would work combined with the battery light glowing faintly and the guages working but being low. On the Cavalier it was the common live feed to all of them on the back of the dash that was broken (tracing the actual break was made more difficult by the sequence of things coming off the live being the inverse of what the schematic in Haynes showed - the closest to the break being the furthest away on the diagram and vice versa) So I'd reckon it's a common live problem.

[cobblers]

This seems like the old mk2 Cavalier problem, whereby the battery light wouldn't glow, the fuel and temperature guages wouldn't work, but if I revved the car to 5k or so, the alternator would work combined with the battery light glowing faintly and the guages working but being low. On the Cavalier it was the common live feed to all of them on the back of the dash that was broken (tracing the actual break was made more difficult by the sequence of things coming off the live being the inverse of what the schematic in Haynes showed - the closest to the break being the furthest away on the diagram and vice versa) So I'd reckon it's a common live problem.

 

This does sound pretty plausible in this situation. Have a look at the wiring round the back of the clocks again!

[Lankytim]

Looks like the clocks are coming back out again then! Just a thought, maybe a wire on the ignition switch has broken...

 

The dim battery light and half working gauges now happen pretty much all the time, rather than after 5 miles or so. At this rate the Audi will have "healed" itself by the end of the week .

[Lankytim]

Today on my lunchbreak I thought i'd atleast show willing and have a look at the clocks again. With dodgy Mk2 cavalier instrument clusters in mind I got a working multimeter and out came the clocks for the 9678 time. I identified that the permanent live and switched live from the ignition switch were working on the multiplug going into the rear of the instrument cluster but didn't seem to be doing anything, so the cluster was probably to blame. Getting it on a work bench at work I spotted that a "route" on the flexible printed circuit board was broken and looked like it had burned out? Anyway I cut an inch of thin wire from a reel knocking about and soldered it onto the PCB to bridge out the damaged part (lucky I work at an electronics firm!) I plugged it all back in to the dash and turned on the ignition..... It worked! Normal operation is restored, its amazing how such a tiny fault in the PCB can throw up so many other problems, anyway, I'm chuffed to bits that its all working again, and its thanks to the members of AUTOSHITE!!

 

Best of all the problem has been fixed for free too!

[Rocket88]

Good man, top bodging Sir Lanky!

[scooters]

Today on my lunchbreak I thought i'd atleast show willing and have a look at the clocks again. With dodgy Mk2 cavalier instrument clusters in mind I got a working multimeter and out came the clocks for the 9678 time. I identified that the permanent live and switched live from the ignition switch were working on the multiplug going into the rear of the instrument cluster but didn't seem to be doing anything, so the cluster was probably to blame. Getting it on a work bench at work I spotted that a "route" on the flexible printed circuit board was broken and looked like it had burned out? Anyway I cut an inch of thin wire from a reel knocking about and soldered it onto the PCB to bridge out the damaged part (lucky I work at an electronics firm!) I plugged it all back in to the dash and turned on the ignition..... It worked! Normal operation is restored, its amazing how such a tiny fault in the PCB can throw up so many other problems, anyway, I'm chuffed to bits that its all working again, and its thanks to the members of AUTOSHITE!!

 

Best of all the problem has been fixed for free too!

 

bodgetastic!!

 

THATS the way!!!

 

well done sir -

 

you'll be making wheel arches out of cornflake packs next!

[M'coli]

Tip-top! I'm glad to hear you've got it sorted.

[Lankytim]

ITS NOT A BODGE ITS A PROPER REPAIR!@!!!!

[Richard]

It is indeed a proper repair, it's an official way to repair damaged PCBs.

[M'coli]

You mean that staples, solder and correction fluid isn't? Ah, I proper bodged the Cavalier then!