Dead Battery ? Possible Other Problems Or Not?

JudderMan

Registered User
I didn't think it would be long before I posted something wrong with my car :)

2005 A4 2.0TFSI

Did 700 miles the other day so not exactly a short journey, parked up overnight and tried to start it the next morning, flickering hazards/dash lights and no starting, the alarm battery (I presume) in the rear of the car was going off. Got a jump start off a friend and it fired up pretty much instantly, too it for a good drive 25 minutes or so, and then the next morning (today), dead battery again.

I made sure that the doors were locked and that the interior lights weren't on last night, which I thought was the first problem as I read online that the door locks on A4s can cause it to drain the battery as it thinks the doors are open.

I did notice the hazard light stayed illuminated once the car was locked..

After Googling a lot, it seems there is a comfort ECU under the passenger seat, which I hope it's not that but wondered if anyone else has any ideas - I have heard that door locks can be faulty and cause this but I don't think I'm getting those symptoms that are indicative of this problem. I have ordered a Bosch battery as I bought the car with a Halfrauds unit and I don't trust anything from that shonky outfit.

Hopefully it's just a dead battery....
 

Molnboman

Registered User
Sounds like a goosed battery Mate.....and once they go they are never coming back. Best to replace for peace of mind anyway.....At least you know it's going to be fresh for Winter starting. Have you had the parts fitted yet?.....Oh remember to clean the battery area and get the drainage gromets removed from under the battery area.

BR
A
 

JudderMan

Registered User
Thanks Bez and Molnboman :) Just read some horror stories about ECUs and door locks and £££s of parts. Also, didn't know that about the drainage grommets, good shout, as my A3 let water into the cabin through the pollen filter having a split housing...

Haven't fitted anything yet, got called away on business so only just getting round to stuff this week. Hopefully the weekend stays dry and warm as it is today. Although as soon as I lift the bonnet on any of the cars I have had, winter sets in immediately haha.

Still waiting for the magnetic sump plug to arrive and LEDs so might just wait until I have everything and do a full car day.
 

rizzini7

Well-Known Member
VCDS Map User
Mine, did it last year on the way upto Scotland. Died in kfc car park at 20.30 on a Saturday night. Got jumped by breakdown and was dead at premier inn next morning. Quick jump again and a trip halfords for a new battery and has been fine since
 

JudderMan

Registered User
Mine, did it last year on the way upto Scotland. Died in kfc car park at 20.30 on a Saturday night. Got jumped by breakdown and was dead at premier inn next morning. Quick jump again and a trip halfords for a new battery and has been fine since

Thanks man, that's kinda what I wanted to hear (but feel sorry for your situation at the time). The UPS guy has just delivered the battery 10 mins ago :)
 

JudderMan

Registered User
Turns out the brake switch is broken as the brake lights were staying on all night causing the battery to go flat. I stuck something heavy on the brake pedal last night to stop it as it's the only thing I could do. Didn't want to get the tools out at 1am to disconnect the battery. Weirdly the brake lights only came on about an hour after I locked it!

Either way having a nice shiny Bosch battery gives me a little more confidence than a Halfords crapper especially for the winter. Off to Audi in 25 mins for a new switch.

Thanks again all :)
 

JudderMan

Registered User
7 quid for a new switch. 5 minute job and done. Maybe should have swapped out the clutch switch while I was there but didn't think.
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Definitely time to carbon wrap that nasty 'wood' plastic trim.
 

@udi A3

Well-Known Member
VCDS Map User
Just replaced my tired battery this week for a spanky stop start spec one. no warning that it was going to die, got to work wouldnt start, got to halfrauds after jump stard wouldnt start.

Funny quotes from halfrauds fitter.

It should charge at 13.6v , as its charging now at 14.1 i think your battery boiled dry.

That captive nut is loose, youll need to get audi to cut the bolt off to remove battery.

Ended up yanking battery out myself and manipulating the new one in myself. Had a bit of fun with my spare key though, no immo chip made the poor guy think he had broken my car haha
 

JudderMan

Registered User
Haha don't trust a halfordian. They're from a different breed.
 

Redski

Registered User
Turns out the brake switch is broken as the brake lights were staying on all night causing the battery to go flat. I stuck something heavy on the brake pedal last night to stop it as it's the only thing I could do. Didn't want to get the tools out at 1am to disconnect the battery. Weirdly the brake lights only came on about an hour after I locked it!

Either way having a nice shiny Bosch battery gives me a little more confidence than a Halfords crapper especially for the winter. Off to Audi in 25 mins for a new switch.

Thanks again all :)

Hi JM ... I think I'm experiencing the same issue as the symptoms I'm getting are the similar to those you describe !

How did you diagnose the Brake Switch as the culprit ?

Cheers,
 

JudderMan

Registered User
Hi redski

I saw a thread about the brake switch can't remember if it was on here or a different Audi forum, but it cured the problem.
 
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