Hello all,
I had major electrical issues this afternoon. I was in Orlando yesterday and had Mike Norris do a gear swap and tune. He is great to work with and did an excellent job. The car ran great on the 7 hour trip home. By the way, the only electrical problem I've had with the car since I've owned it is the EBCM. Anyway, during the trip home the only funny thing that happened was that I had some water dripping out of the heater vents towards the end of the trip. I just figured some condensation had formed in the vents. I parked it in the garage for about 8 hours and went outside to wash it this afternoon. When I went to wash it, there was a large puddle of water beginning at the passenger side where you normally see AC water dripping. I thought nothing of it since I had run the AC the whole trip. I washed the car as usual and did not spray the engine. After drying it off I went to start it and got 'reduced engine power', service vehicle soon, none of the gauges worked except for the speedo, tach and volts (fuel was empty, oil pressure and temp did not work), the radio did not work and the display was blank. Every possible warning light was on. I tried to pull the codes at that time and every module said 'no communication'. The engine was running fine and I could move the car into the garage but didn't try driving anywhere.

I disconnected the battery, checked the passenger foot well for water...nothing. Checked BCM fuses, they all looked good. I wiggled door acordians. I couldn't find anything obvious. The I hooked the battery back up and everything is now working normally. I want to say this has something to do with water since I had water drip out of the heater vents and also since this happened after washing it but I couldn't find anything wet. Any ideas??

Tim

 

I think if you have water coming inside it might be time to clean the udders.

 

I thought of that too initially. Driver's side udders are clean, I may pull the battery tomorrow and check the passenger side and also try and get to the AC drain. The BCM and passenger footwell was dry as a bone...

 

Tim, Your problems sound very similar to what happened to me after I had my gears swapped out on my A4. The last thing before I left my mechanic was they reset the PCM for the gear swap. I left the shop and after about 5 miles everything stopped working. speedometer, and all gages. I pulled into a parking lot and after a minute or so shut off the car and called my mechanic. He said bring it back and they would check it out. When I re-started the car everything worked and when I got back to the shop they couldn't find anything wrong. No codes?

That was 6 months ago, and about 2500 miles, and not a problem since. Hopefully yours is the same and doesn't re-occur.

 

I gave Mike Norris a call during this episode and he figured it was some sort of communication issue most likely involving the BCM. After unhooking the battery, checking fuses, checking the star connectors on the BCM and wiggling the door wiring harnesses everything went back to normal while we were still on the phone. The thing is, it was fine during the 7 hour trip back and didn't start acting up until after I washed it. I just couldn't find any wet electrical components. I'm going to clean grounds and check the AC drain tomorrow. I just wish I could reproduce it so I could find the exact cause....

 

You checked all the things I would have checked

Hopefully it was gremlin

 

Update:
Once everything was working again last night, I took it for a drive and had no problems. I checked the codes and had a bunch of U codes which I cleared. One in particular stood out which was a U1300. This AM I was reading on the forum about the serial data bus and I found that U1300 means that the data bus has a short to ground. Now I wish I could remember which module had the U1300 code because that was probably the answer. Anyway, I did pull off the door accordions and found the bare data bus wire that seems to cause these kind of problems. I found it on both the driver and passenger sides and covered it with electrical tape. I also cleaned the connectors with contact cleaner. Anyway, I haven't had any issues today. Hopefully it was one of the data wires in the door that was grounding out.

 

Looking at the book U1300 is "Low voltage on the class 2 serial data bus". It only takes a 3 sec drop out to set the DTC. Any of the modules on the bus can set the code and once its set it inhibits further DTCs.

I'd still say you're doing the right things. When you say the wire was bare had it chafed? If so that would certainly do it.

You dont mention your battery. Is it still the OEM AC Delco? If so, we had the AGM version on the 02s. They are well known for premature failure, particularly if they've been drained at some time. It may be worth having it load tested; Autozone will check it for free. If its original, 6 years is about right for it to be coming to the end of its life, particularly in a hot climate. That would also generate the U codes if its starting to go flakey. A pre-emptive change may be worth the investment.

 

Great job. Congrats.

 

The wires weren't chafed but in those door connectors, they aren't insulated like a regular wire. Instead the data bus wires are covered in plastic tubing (like what you'd use on your fishtank) which leaves about 5mm of bare wire. The connectors are stuffed into the space where the bolts for the door hinges stick through. My theory is that from opening and closing the door the connector works it's way to coming into contact with one of those bolts and grounding out. I had a great view of the area while I was upside down under the dash but didn't think I could get a good picture of it.

As far as the battery goes, I put an optima yellow top in it last fall. I thought I had a bad battery at the time but it turned out that the lights on the drivers side vanity mirror weren't going off when the mirror cover was closed. That was an easy fix..... I taped a quarter between the cover and the switch so that it pushed it down enough to turn the light off.

Going back to the original issue, I drove it quite a bit on Friday and yesterday with no problems. I'm keeping my fingers crossed...

 

Doc

Im in GUAM and just saw this post. Sounds like you did EVERTHING right! I would have first guessed a wetted BCM and if that didnt pan out, the door wiring harness seems to be the next thing to cause the issue. Insulate it with liquid electrical tape and I bet you the issue will be resolved.

Good recommendations and good job on the trpoubleshooting and repair.

Bill