Electrics gone crazy, car won't start sometimes...

[_a3sport]

Started out today with boot open warning on dash, locks trying to lock every few minutes on drive to work, then alarm started going off at work, ok perhaps dodgy boot sensor. Took boot apart, checking connections, no water etc, then went to start the car. Now won’t start, turning over, the odd splutter where you think its nearly going. No lights on dash, heating and stereo working. After disconnecting the battery for the second time it magically sprang to life. Ran it a while, restarted it, now it runs with no dash lights, turned it off and now have ABS warning on dash. Tried a few more times, sometimes dash lights work, sometimes heating lights on, now back to the beginning and not starting. Also boot warning now gone. Went out again later, lights stayed on when unlocking doors then car started, with no dash lights...

Any suggestions? Main battery earth was good, checked all fuses in car. I going on holiday first thing tomorrow so the next chance I’ll actually get to have a look is Sunday night (in the dark again!).

 

[hades-]

no sure if its the same as the a4
but under the binnet of the a4 theres a ecu box
with some fuses and relays
on the a4 water gets in and causes problems like you have
worth a look

 

[_a3sport]

Cheers, will take a look on Sunday night.

Any other suggestions welcome.

 

[Ash187]

Replace the battery?

 

[_a3sport]

Got back from hols, car back to normal, half way on 50 minute drive to work DIS boot warning on again. No sign of water in fuse box, battery voltages check out OK when off and at idle. Back to the beginning then thinking its just the boot lock microswitch so I've ordered a new lock. Seems to be quite a few people saying these go with and without signs of water ingress. Hopefully thats all it is...

 

[pondside]

Hi, What was the outcome, did you find the fault? I have exactly the same problems, or have you got rid of the car and I just bought it at auction?

 

[_a3sport]

In the end it was the connector for the boot lock sensor which had an intermittent connection. Easy fix once you have it. You can get a new one from Audi its wasn't much £5 or so. Could be that or the boot lock sensor (£35) on yours.

 

[_a3sport]

Is your car going crazy like mine? I beleive it must be as the alarm drains the battery badly. I was disconnecting the battery if I left it for any period of time as a new battery is £80 or so on a diesel. You can also remove the alarm fuse but I'm not sure if this actually disables alarm and headlights from flashing.

 

[pondside]

I have only had this car 24 hrs so haven't had time to check out all the problems but yes the battery drained overnight and wont start until boosted and the boot light open warning is on, then it goes to service, have also noticed the mirrors don't always work so I guess I'm going to have a busy weekend fault finding, never again will I buy at an auction,
Where are the sensors for the warning light, in the boot or inside the door?

 

[_a3sport]

The sensor is built into the boot lock. You need to remove the lower tailgate trim to gain access. I think there a couple of screws near the middle. The rest is just metal clips, just give it a good yank. Battery might be on its way out to if its been left like this for a while. Depends how much you saved at auction in the first place. I saved about 1K over private on my last car and thankfully it was problem free.

 

[pondside]

Gaaday_a3 Sport

The car is all fixed, I found that the rear window washer was leaking directly onto the lock mechanism and the micro-switch was short circuited, this is what caused the battery to slowly drain.
I fitted an "O"ring to the wiper shaft, that cured the leak and obtained a new lock on ebay for £22.
What a bargain and saved myself a packet no doubt.
I bet the leaky wiper shaft is a common fault so I would advise any one with this model to remove the wiper mechanism plate and fit a small "O" ring, I wonder if I can put a patent on this repair. LOL!

 

[_a3sport]

Glad you got it fixed, my wiper doesn't leak (yet), think a wiper is pretty pricey so good job!