Thats what it sounds like to me. Ill dig into my Bentley book and see if i can find any wiring splices in there diagrams later tonight.

if not u may be pulling wire looms apart looking for chaffed wires.

 

Great. You need the wiring diagram. That c7 circuit is connected to a few systems such as the lamp switch, term XE relay, etc .

PM me with your email if you need the wiring diagram.

 

Ok, try remove relay #4 and #9, one at a time and see if that changes anything. Then unplug the headlight switch.

All done with key removed from ignition.

 

I found the 1999/2000 model year diagram online, I think it's probably close. I dug some more and found that pin 86 of relay 18 was always hot, which made sense considering the fault. The more I thought about it, I realized that the fused side of C7 should go directly to pin 86 so the fault HAD to be between the fuse box and the relay box. I pulled out both of them and clipped the wire at each end and installed a jumper and viola, the temp sensor turns on and off with the key! Juding by the complexity of the wiring loom and its sheer size, the jumper may be a permanent fix. I have no desire to unwrap the whole harness looking for a melted or chafed wire.

Temporary jumper wire.

 

Cool. That would be a good fix if it doesn't affect the other systems on the same circuit.

 

Yeah, that's my concern as well. Everything seems to work OK so far, no warning lights and the AC compressor does engage. I will give a cursory look at the harness to see if I can find anything obviously wrong but in all likelihood, I will locate some matching wire and solder it up and put it all back together.

I really appreciate all of your help on this. You started me down the right path, thank you!

 

Anytime.

Since your issue is power leaked into that circuit, it may be worthwhile to check for any parasitic drain when the emgine is off and the alarm is armed. Should see no more than 30mA or so after 1hr.

 

Good idea. I'll do that. Thanks again!

 

I guess I'm not quite out of the woods yet! Driving around today I started messing with everything electrical I could to see if my "fix" had broken something else. I found that the rear window defogger was not working. A parasitic draw revealed a 250 milliamp draw that was reduced to 25 milliamps when I removed fuse D2 (defrost and mirror heat);

I also noticed that my seat heaters can be turned on with ignition off, which doesn't seem right either but I don't know any better.

 

Yeah, that's what I'm afraid of. Perhaps go back to post #18. You may be able to isolate the source of the leak if you're lucky.

 

I'm gonna go back into it this weekend. Pretty sure relay 4 is also actuated by fuse C7 which must still be shorted.

Should the seat heaters be switched with the ignition?

 

The power of the seat heaters come from the Term XE relay (relay #9), which is currently activated by the shorted +12v without the key.

 

I have more digging to do! At this point I have relay 4 removed and have a 25 milliamp draw, which I think is fine. Removing relay 4 also disabled the heated seats so they are unintentionally connected! At least now The battery won't die overnight until I can track down the issue with the seat heat/rear defog/mirror heat.

I'll report back when I find out more. Weird that I seem to be the only one to ever experience this.

 

The problem is that C7 circuit is still shorted so it's powering a few things that should not be powered with the key removed. That's despite the fact you cut out the temp sensor fan. The C7 circuit is still getting power from somewhere.
If you can revert your fix, then remove relay #4 and #9 one at a time, you may be able to isolate the source of the leak.

 

If removing relay #4 will remove the +12v on fuse C7 fused side, then relay #4 is leaking +12v into the circuit.