In the continuing saga of why-can't-I-have-nice-things, my '04 CE Z06 has gone from bad to worse.

Original problem: around the time (but not exactly) I replaced my tail lights with LED, I began getting a traction and stability control warning. I eventually deduced that this occurred only when I used my hazard lights while driving. Brake lights, turn signals, etc. no problem, and no problem using hazards when stopped. These systems are then disabled until I turn off and restart the car. This is a fairly common problem and I've read up on it, seems likely to either be bad ground somewhere or the supposedly already-compensated LED taillights need additional resistors.

Recently: I've continued to drive it, avoiding using the hazard lights (and they're the "thank you for letting me pass" signals in the mountains here), without problem. Then one day after a hard acceleration over bumpy ground I got a "service vehicle soon warning" and "charge system fault", as well as TC and SC disabling, AND now ABS warning too. Same as before I restarted and most of the errors went away, though the service vehicle warning showed upon starting. (Also I got a low engine oil warning and in fact it was 1.5qt low. Maybe that's just coincidence? No signs of a leak or smokey exhaust. It'd been a while since I checked the level.)

Today I decided to drive it in to work and just as I picked up speed it started spewing warnings and then the whole display shut off, though HUD still worked. When I returned to idle it powered up again. The voltmeter was showing 16 to 18V when it was working! I got the "charge system fault" again and now also "high voltage." Seems like my voltage regulator failed? Could that be related to all of my other problems? Returned home and parked it of course.

I have a Tech2 but haven't hooked it up yet to investigate. I'm dedicating at least one day this weekend to car maintenance so I'll do that. Does anybody have any theories about what's going on with this thing? Could the voltage regulator be the root of it all, or could bad grounds (my leading suspect between the 2nd and 3rd symptoms) kill the voltage regulator in addition to all the rest?

Thanks for any ideas!

 

in a lot of cars the LED lights pull so low current it screws up the ground system. have you removed them back to original to see if the problem goes away? i would.


and yes having had three fiberglass cars, bad grounds will screw with you more then you can imagine

 

This seems less random than that but I'll definitely be checking those now regardless!

bobs77vet, haven't tried yet but plan to. It just mystifies me that the hazards would do it but brakes and signals don't if it is just an LED issue.. I've had a 77 and a 70, tell me about it! Good grounding isn't that hard but they always seem to skimp on it.

 

Take a look at this thread. When taillights are replaced with LEDs, it seems that in some cases this problem gets triggered by using the hazards and in others by using the turn signals. Although the thread was not updated with the final results, I think it's worth exploring.

It seems the key element that unchained this cascade of problems was the hard ride over a bumpy road, which tends to point to bad contacts. With so many different systems having problems at the same time it has to be something common to all of them, and I agree with 8VETTE7 that it's probably the Serial Data Bus. The best candidates, as mentioned in Post 3, are the connectors in the door accordions and let me just add a picture to illustrate this:



Regarding the overcharging messages and the 18v etc. it might be bad contacts as well, in the alternator-starter-battery chain. This is a quote from a thread that was describing almost exactly what is happening to you. I think it's worth a check.

 

I made new ground and positive cables for my LT-1 out of 00 welding cable!

My last car before the C5Z was an '06 M6! Glad to have experienced it but probably good I totaled it before it became a maintenance disaster. Car work day tomorrow!

 

Well, whadya know. I opened up those connectors and didn't see any contacts as obviously bad as the pictures above but I "fluffed" them up as well as I could and gave them a glob of dielectric grease. I haven't driven it yet but no sign of problems on start and the voltage stayed in the right range when revving. Still the hazard light problem so I'll be trying the factory lights first. The LED tails are supposed to have come with internal resistors so I'll try the factory center brake light first, though I don't think that blinks with the hazards...

 

False alarm, same problem this morning. It was significantly colder and more humid, perhaps it's sensitive to that. On to ground R&R, though I'll still be seeing if putting the factory lights back in helps at least some of the symptoms.

 

 

4 1/2mo later and I've finally gotten around to this! I tried fluffing up the contacts and using some dielectric grease to no effect. Actually, shortly thereafter the window and door locks on that side stopped working, which at least further confirmed the wiring in that door was suspect. So I finally went in and cut out the factory 6-pin connectors and replaced them with fancy new Deutsch DT ones. I didn't bother with the 10-pin connector, at least not yet. This sadly had no effect, so I pulled off the door panel and discovered that the connector to the passenger door switch panel is highly corroded and the switch unit itself crumbled when I removed it. So I've got a new aftermarket switch unit coming for both sides. Doesn't look like new door wiring harnesses are made, so I might just make the connections pin-by-pin, or maybe pull off the connector (as long as it doesn't crumble too) and just replace all the pins and generally clean up and re-wrap the original harness. I also ordered a refurbished DCM, which could be the root problem also, though I didn't have time to run electrical tests, so it may be fine. The car does have >135k mi on the chassis on top of its 14 years of exposure to sun and oxygen, so the usual things are deteriorating. Seemed like some water is getting into the door innards and the big rubber sheet covering the main door hole has disintegrated, so I'm going to do some waterproofing improvement throughout. I'll keep you all updated once I finally solve this!

(Note: no idea if the door speaker is working, which could implicate the 10-pin connector, as the radio has been out awaiting a new head unit install for all this time.)