Roof light drains the battery

Per

Roof light drains the battery

Unread post by Per »

I seem to have got a problem with the roof light console as it occasionally draws power even though all the doors are closed. What seems to happen is that the light doesn't fade out completely. Sometimes there's a small spark left in the bulbs, despite everything being turned off. This is bloody annoying as I keep having to disconnect the battery to make sure it doesn't drain out.. Anyone know if this is a common fault and if so if there's a quick and easy solution besides replacing the whole shebang? I do know this fault was fairly common with SAAB 9000's...
Per

Re: Roof light drains the battery

Unread post by Per »

Oh, I forgot to mention that my car is an S3 2.0 16V Turbo.
Pol

Re: Roof light drains the battery

Unread post by Pol »

Maybe you can check the contact-switches on the doors, there could be a short-circuit in on of them.
Another possibility is the pushbutton on the rooflight itself.
smokeme

Re: Roof light drains the battery

Unread post by smokeme »

I doubt the bulb alone would drain the battery very fast, i had a door light stuck on and it took over a week to be noticiable. A short somewhere on the circuit is more likely, maybe a pinched wire somewhere...try to find out how it was solved on the SAABs.
david hanson

Re: Roof light drains the battery

Unread post by david hanson »

a bulb can drain a battery quite quickly
The boot light on my car stayed on (pinched wire) and it flattened the battery in less than 2 days - really flat, so flat that a jump start would not help.
BTW my auto electrician found the fault by shutting his apprentice in the boot!
Per

Re: Roof light drains the battery

Unread post by Per »

So what I need is an apprentice then? :-)

Yeah, I know for a fact that a bulb (or two as it is in my case) can leave a battery for dead in less than 24 hours as this also happened to my old Volvo 240. Anyway, I'll start with the contact breakers in the doors and take it from there. Many thanks everyone!
smokeme

Re: Roof light drains the battery

Unread post by smokeme »

The easiest way is to take out fuses one by one until the drain vanishes, then simply check what's on that circuit.
Leo

Re: Roof light drains the battery

Unread post by Leo »

Hello Per,
Check the circuit board in the overhead lamp unit (remove lens and then two allen headed bolts. If any dampness has got in it will have corrosion that could be triggering the current drain. (Am assuming that this is an S3 Thema). I bypassed the circuitry as the dim on/off function seemed mad to me. I was usually inside before the light came on ! A bit fiddly to cut the tracks and solder in bridge wires but it is possible.

Leo
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