Conundrum

[1781cc]

I've been trying to find the cause of an electrical woe for a while and it's been getting progressively worse. It started in that after 3 days of not driving the car wouldn't start as the battery was dead, turn the key, lights come on briefly but dim, click, click, click, nothing.

Charge the battery and it's fine, jump from a pack when flat and she is fine.

Gradually it's been getting worse and worse and I've this is what I've covered:

- checked fuses
- replaced battery
- check central locking pump for over run
- had a garage check for a drain, nothing found
- disconnected everything non essential, stereo, sub
- once started she sits at 14v on the VDO, so alternator seems fine

Where to look next please? Alarm? Ignition? Other ideas?

I'm at a loss at the moment and I the battery is rinsed overnight now

[PRY4SNO]

Long shot, but maybe check your voltage regulator (brushes) in the alternator. I had a similar symptom and they were worn right down.

[UrS4boy]

Battery seems to have a dead cell IMO.

[PRY4SNO]

He replaced the battery.

[UrS4boy]

He replaced the battery.

Oops. Missed that.

[Rikki Kitto]

I had an ECU relay fault that was draining mine over 3 days

[LHD_Kid]

If the battery is good and goes flat in 3 days just sitting. There HAS to be a drain, quite a large one...

Edit: flat overnight..? Huge drain. I think you should take it to a different garage! Not really helpful I'm afraid, but I get the feeling the garage that told you that there is no drain might not have been very thorough. ...

[UrS4boy]

After run pump 324 control modules are known culprits for causing battery drain, as is the 329 window control module.

[bluequattro]

Keep it simples people
Boot or door wiring
Happened to my tdi
Would be fine for ages then drain a new battery in a few hours

[1781cc]

Forgot to mention, its an AAH 12v 2.8 v6 Cabriolet, so I think the after run pump is out, will check the 329 window module and try to travel boot and door wiring, what should I be looking for with the wiring? it seems the boot has been fixed once before with cable blocks, so I will resolver them properly and heat shrink.

I thought it might be central locking pump, so I've left it on occasion overnight unlocked and its done the same thing.

When I get a chance I will see about the alternator bushes - initially that would make sense to me as its got progressively worse. I realise I lied earlier, after jumping and driving home tonight, it started at 14v on the VDO then dropped to about 13.2v whilst driving and thereafter, is that right?

Could it be the clifford alarm draining it?

[K Simmonds]

It could easily be the old (well that's an assumption) alarm installation, they tend to be poorly fitted and inherently go wrong and cause all manner of problems. The only car's I've owned that haven't required removal of such systems are my RS2 and my very first 1.3 MK2 Golf and I've had (still got) quite a few cars. The Clifford concept is affectionately named the "Clifford come back" in the trade given how rubbish they are, especially when installed by someone who should be supervised with crayons let alone a soldering iron.

The voltage reg is a possibility but given that your getting 14V on the gauge and the car doesn't die while running it's not that likely but it wouldn't hurt to change it anyway as a bit of preventative maintenance. Their not expensive and easy to fit, if your car's still on the original there won't be much life left on the brushes. Have you checked with a multimeter to see what voltage your getting at the back of the alternator and the battery with the engine running? The VDO is not 100% reliable.

Door/boot shuts are the other suspect, I'd do away with the previous poor repair and do it properly with solder and heat shrink.

You could try pulling the fuse for the stereo to rule that out, in fact with a bit of trial and error pulling fuses and disconnecting stuff you should be able to work out if it's a wiring fault. Hook up a multimeter to the battery with the ignition off and pull and replace each fuse one at a time, when the voltage suddenly goes up you've found the faulty circuit.

[1781cc]

OK, I spoke to the garage again to explain what they checked and they said they checked the alternator, it was fine, they also explained that if the alternator was going I would have battery warning lights coming on and I would see things that I am currently not seeing whilst using, e.g., lights getting dimmer at night, etc, they also explained that once the battery had gone flat and I jumped it, it won't be the alternator because over the course of the day I could drive and start again no problem, if the alternator was at fault I would be continually jumping because nothing would be going back in, i.e., it would drop to 10v and not be able to start again.

They also checked the central locking pump, they explained there was a brief drain after the car had shut down and that was due to the pump going to sleep after it was locked and it didn't drain after that.

Further to the comment about the window control module mentioned above, they said it could be, best suggestion to find it is take a picture of the fuse box and pull all the non-essentials out, i.e., wipers (if its a dry day), rear demist, stereo, etc... make sure the battery is charged fully first, and by process of elimination, start putting things back in each time to see if the problem returns. If all non-essentials are out and its still doing it, it points to another module drain from the essentials (i.e., echoing that mentioned above) so thats what I will start tackling this weekend.

I hate electrics!

Thanks for all comments and suggestions thus far, appreciate the help guys

[1781cc]

K Simmonds - I must have been typing the same time as you, but it seems your thoughts about fuses echoes theirs, so will be tackling that thanks!

I have a multimeter, never used it, so will watch some youtube videos to see how it works (yes, I am a dunce)

I'll take the preventative comments onboard and change the bushes anyway :-)

[bluequattro]

[QUOTE=1781cc;it seems the boot has been fixed once before with cable blocks, so I will resolver them properly and heat shrink.
QUOTE]

I'd put money on this then

[1781cc]

Update for anyone else having a similar issue, after my starter motor failed, the garage traced a problem back to the ignition, part number 8A0 905 851 B fixed the issue

All solved now