VaporiZe

I have had a battery drain on my 91 GT for some time now that would prevent it from starter after 3 or 4 days of sitting and I finally decided to tackle the problem yesterday. I have removed every single fuse, relay, and plug from the fuse panel and this is what I have found

I did all my testing with a test-light on the battery and fuse #25 disconnected "Diagnosis connect; Current pulse tailgate; inside light" so I could work with the doors open and not interfere with the battery draw. When fuse #22 "Electric power seat left side" is pulled the test light dims, but remains on. No other fuses or relays effect the test light. When I remove plug K (Red and pink) from the bottom of the fuse panel the test light flashes and the alarm system CPU under the passenger seat can be heard clicking. If I then remove plug L (red and white) the clicking stops and test light finally turns off. If I leave plug K in and just pull L nothing happens. I removed the passenger seat and unplugged the alarm CPU and then I could remove just plug K and the test light would turn off. However, if I close the doors and hatch and work from inside the car with fuse #25 put back in nothing happens with removing fuse #23 or the two plugs.

With the battery reconnected and plug K removed I found that the seat controls, mirror motors, windows/moon roof and radio do not work.

Because the test light dims when the fuse for the driver seat is pulled then that has to be at least part of the problem... right? But the driver seat works perfectly fine along with the seat memory positions. My window/moon roof buttons do stick going down, but I bought the car with the buttons sticking and the battery drain didn't start happening until years later. The previous owner warned me that if I ever have any weird electrical problems with the car that it would most likely be with the aftermarket Blaupunkt radio as they had a load full of electrical problems after getting it installed and took them forever to get it all sorted out.




At this point I am a little lost on where to go from here and i'm not 100% sure what plug J controls. I think I am going to unplug the drivers seat and see what that does and continue down the list of everything that plug J controls to see if any of those things are the problem.

Any advice or ideas on whats going on or where to continue would be appreciated, especially if you've been down this road before.

Simon928

I can't speak to the exact symptoms that you are describing, but I had a parasitic drain on my 90 S4 when I bought it and I was able to track it down in a few minutes to a bad relay by doing a test similar to the one in this link. I find that if gives a much clearer idea as to what's going on than using a test light. I hope it works for you!

Mrmerlin

OK since you know you have dragging window and roof switches remove the tops and file the edges down so they dont stick.

Next since you find issues with the seats make sure the seat switches are not sticking .

I had a car with one seat switch that would stick in the moving the base to the rear of the car position,
and it was pretty easy to forget about it then come out in a few days to a dead battery.

Since the seats are always powered this is a good place to start you might just have to replace the seat switch

Alan

A test light is not a debug tool for this, get a DVM - you can get a cheap one adequate for this for ~$20. But a better->good one will likely get a lot of future use too...

Learn how to use it in series with the battery connection (ground side is best). Not everything is fused... evaluate the additional connections at the B+ lug.

I see you have a few aftermarket connections - evaluate whet they are and what they are connected to? I'd also wipe those numbers off the relays if I were you - the relay slots are already numbered (roman numerals) and these numbers are totally different & confusing. If you want to label them - then label according the the panel label numbers (even if still in Arabic numbers).

Alan

gomez123

I had a draw and it ended up being the electric antenna. I also read a post on the forum the po said it took him forever to fix. It was the interior light above the rear seats. The copper strip was barely touching the frame of the car causing a draw.

VaporiZe

Just double checked the seat switches and none of them sticking. Going to remove the seat next

VaporiZe

I believe all of the aftermarket wiring is for the radio. There was an amplifier in the back and the way they fixed all the electrical problems with the radio was removing the amp and leaving half of the speakers in the car disconnected. So all of aftermarket connects are dead and lead to nothing.

VaporiZe

Removed the drivers seat, as soon as it was unplugged the alarm CPU started clicking again, unplugged the memory control module under the drivers seat and that did nothing. Does anyone have a proper wiring diagram that will show where the wires for plug K and L will lead too?

uraniummetallurgist

I've had similar issues and the DVM is the way to go to get the faulty circuit(s) identified. However; it's a rat's nest in some places with all the wiring and finding the problem wire is often difficult. Especially when wired go under carpet or behind panels.

I ordered one of these automotive cable wire tracker.

Here is a good Youtube video on how it's used although it's a slightly different unit.
.

All the best and good luck!


Joe

Ducman82

Once you know how to hook at DMM between ground and the batter ground (interior lights fuse out) pull fuses 1 by 1.... I had to do this on a 90. Turned out the driver seat had a switch issue drawing 320ma! System was back to 69ma draw. Turned out to be the alarm. Reset it, draw down to 30ish where it should be