jaredwilson

New member here.

First of all, I would like to thank everyone who contributes to this forum. This forum and its contributors have saved me literally thousands of dollars over the last few years of Audi ownership. I have a '99 A4 2.8 Quattro with Tiptronic. I've replaced the drivers seat with one purchased through Shokan, repaired the fuel sending unit using $0.10 of Teflon coated wire, replaced brake pads and rotors at all four corners, flushed the brake lines and had the ABS module rebuilt by Modulemaster - all of which was made possible by the information captured in the AW forum archives.

My car has recently developed a parasitic battery drain and would be completely dead without being driven for a day or two. I put a multi-meter between the negative terminal and the battery cable (using the rubber surround on the cable end to hold the multi-meter probe - a tip provided by Mark a local Audi mechanic). The draw was on the order of 132-133mA which was reduced to around 15 mA when Fuse #14 was removed. According to the manual, fuse 14 is responsible for the interior, vanity mirror and reading lights as well as the anti-theft alarm system. I've been living without the fuse for about a week now, the key fob remotes and central locking still work along with the horn to signal that the doors are locked. The only difference with the central locking system is that the lights don't flash when locking/unlocking the car.

I've tried pulling all the interior and trunk light bulbs one at a time, but none of them reduces the draw. I'd like to try to disconnect the central locking control module under the rear seat to see if that drops the draw. I've borrowed the Haynes manual from the local library, but fuse 14 is not identified in any of the wiring diagrams and in addition, the wire colors in the car don't match those listed in the diagrams. Does anyone have a wiring schematic for fuse 14 that they'd be willing to share? Also, any tips or advice on tracing shorts would also be appreciated.

Thanks!

turbo510

Are you sure the draw is only 130mA? That should take about 2 weeks to discharge a 40AH battery. If you disconnect the battery ground cable, is there a spark visible? Go ahead and disconnect that central locking module, if the current drops to the 15mA, then maybe it has a faulty component.

David.Norton

Batteries never seem to last as long as you think they would based on the amp-hour rating, maybe most batteries are old, and I think the electronics is more dependent in modern cars on having a decent voltage. Anyway, when I measured my car (I was also looking at a short discharge period) it was running about 10 mA, so you are way high. My Bentley says that the wire is red and blue, and that it goes to the central locking module, the door warning lamp module (your guess is as good as mine as to where that is, I've never had need to find it), and the interior lamps you mentioned.

jaredwilson

I disconnected the anti-theft system control module that's under the back seat and the draw dropped to 13mA. The strange thing is, the central locking and alarm still work.

Peter Badore

I think that module is only for the interior motion sensor portion of the anti theft alarm system. What is the part number on the module you disconnected?

jaredwilson

4B0 951 173

turbo510

I think you still need to go back to basics to be sure that you are working with a fully-charged, full-capacity battery. .13A just seems too small to fully drain so fast. Also, maybe that current is fairly normal, and the real discharge happens intermittently, when you aren't aware of it. My daughter's B6 had a brake light switch problem; the lights would go on while parked. This was obvious, but it still took a full day to discharge, from what I remember. Another thing, if your battery is fully drained a few times like that, its capacity goes way down.

jaredwilson

Thanks everyone for the input.

I would't doubt that the battery integrity has been compromised. It's not very old, but it's had a rough existence with the constant draw and frequent jump starts. I plan to replace it, likely with an Optima Yellow top, but I'm currently unemployed, so it will have to wait for a while until I have money coming in again. The local Audi mechanics said that the normal draw should be between 10 - 15mA on the 99 model year since there aren't as many modules running as on the newer models. So 130mA was definitely too high and was putting a strain on the battery, especially in the cold Chicago winter.

I still intend to check the connections on the central locking pump in the trunk to make sure everything is dry and corrosion free. The Audi mechanics mentioned that is usually the problem with parasitic draws and could pull the battery down very quickly. The key fobs will have to be reset afterward though, which shouldn't be a problem.

jaredwilson

Just to update. All three central locking pump connections were clean and dry - no apparent issues there. Also, the key fobs did not need to be reset. I guess it's only if the pump or controller are replaced.

AudiMick

Both of our A4s a 96 A4 and a 2003 A4 drew less than 50mA at "standby".

Had to chase a problem like this on the 2003, the aftermarket ipod adapter wasn't going into shutdown and drew over 300mA. About 7 days to drain a fresh battery.