So I have recently got my car back after replacing the trans and adding a transmission brace. The car drove fine no issues whatsoever but it was not long after that the car has gone absolutely insane.

Here are the symptoms,
1. service abs and traction. 2. reduced engine power 3. no ac. 4. car electronics including lights and gauges turn off then back on. 5. Sometimes happens during driving sometimes after start up. 6. Sometimes security light stays on after the gauges turn off then back on.


The first time this happened I turned on the car and I see on the dash every light you can imagine service traction control service abs, reduced engine power, and the AC does not work and reduced engine power but the car still drives. I drive the car leave it at work and come back to it 8 hours later and starts right up no problem everything works no warning light.

Drove the car a few days no problem then the problem starts up again and now this time sometimes while I'm driving the dash just goes completely crazy as I'm driving car electrics going completely off and come back on and even in one instance the car dying off at idle. The problem has been going on for about a week and the codes lead nowhere as there is so many of them. I have never had an electric issue this crazy but the car never fails to start up.

The most unusual thing is that usually just turning off the car and starting it back up solves the problem at least temporarily.

At first I thought it only happened when it was raining but now it is doing it even in the dry.

The problem is so severe that it has to be something simple At first I thought the negative terminal but that seems ok.
I'm thinking it's a ground issue or possible PCM issue what do you guys think? Any suggestions? anyone have this issue before?

 

I'd look at both ends of the battery cables, the fusible links by the starter and the ignition switch.

 

Oh wow how could I have not seen this I do believe it is the moisture I will check ASAP.

 

Just checked the carpet does not seem like there is any moisture on the PCM at least I unplugged my driver seat connector and the female pin is missing the top most left one. Also keep in mind this is an 04 car so some of the electronics may be a little different .

 

Well,,,,,,,,,,,,,,,,,,,,, You either have a WET/DAMP BCM or a compromised serial data line.

Here is a post for you to check out:

http://forums.corvetteforum.com/c5-t...-there-is.html

 

I read through the thread the problem is in my car it doesn't do it all the time but I do think it is moisture related somehow as I had never driven the car in the rain until recently I will try to post up pictures of all connectors.

 

When it is actively happening,,, open the doors and grab the accordion tube. Feel for the two harnesses inside the tube and pinch them between your fingers.

Shake the crap out of the cables.
IF,,, the problem resolves its self after you agitate the cables,,,,,,,,,,,, the problem is a **** poor connection in the power door connector!

BC

 

Yea that does sound like a good idea I will try it hopefully I can figure it out by tonight.

 

Bill, you never cease to amaze me with your vette knowledge.

 

I had the C5 98 MN6 Coupe from ELECTRICAL hell car!!!!!!!!!!!! It went to shi$ in a hand basket electrically shortly after the 3yr/36 ended!

I was actually afraid to drive it further than I could walk home. It would just STOP running or go into reduced power out of nowhere! Feet don’t fail me now!
After too many hours to count troubleshooting and a lot of forum help,,, I found the problem!

So,,, a lot of that knowledge was born from necessity, desperation, stubbornness and lack of cash to dump at the Stealership!!

Plus, being a 26 year submarine veteran helps the GET ER DONE creativity emerge and develop!

Been doing cars since i was 10 ys old.

Something else that helps is,, I actually enjoy troubleshooting and working on these cars!

Bill

 

I too have the 26 years in submarines and like to get things done. I can only aspire to reach your knowledge level on these complex cars. I did a lot of wrench turning/hammering/bending and tweaking on cars in the mid/late 70s, but cars were a lot easier then (a lot less wires too).

 

Drove the car home from work the dash went so crazy on me that I almost just turned off the car and called for a cab but I disconnected the seat module with no result. Strange thing is the car starts up fine no issue but when I started driving all hell broke loose.

hopefully tomorrow I can better isolate the issue I will try disconnecting the PCM module tomorrow to see if I can isolate the issue thanks for the help so far.

 

I have had to replace my ignition switch twice.

On the first instance the only symptoms were that it died at a stop sign on the way to work and restarted normally. When I tried to start the car to go home that afternoon, I got multiple warnings on the DIC including service traction sys, reduced power and all the warning lights on the instrument cluster flashing on and off. The ignition switch was replaced and all symptoms dissapeared.

The second time, three years later, the symptoms progressed from an ocasional crank, no start but crank and start normally after turning the key off and trying it again, to finally the same as above, multiple warnings on the DIC and flashing warning lights on the instrument cluster. A second try resulted in a start with reduced power warning and NO power. A third try resulted in a normal start and run but with a service engine light.

The car started normally several times thereafter.

After replacing the ignition switch again, all symptoms dissapeared.

An examination of the second replacement switch revealed several burned contacts.

 

Don’t even bother shaking. (I shook mine and ‘fixed’ it several times temporarily.) Pop the accordion off and disconnect the connection. Look at the female side of the connector and adjust the pin holes so they are tighter. After “diagnosing and trying everything under the sun” to fix the same issue, this is the one that finally fixed the problem. Just be careful not to blow out a fuse (which I did – easy to replace I know, but made me feel stupid. ) or disconnect the battery first.

 

I had many of the same symptoms. Cleaned the 2 connectors in the drivers door cleaned the grounds on the right side of the block above the starter, the one on the back of the driver's side head and the two junctions located on the frame behind the headlights.

Problem solved.

 

My first experience with everything on the dash going crazy was cured by a can of techron in the tank; also I learned the importance of checking the chassis grounds from Bill Curlee......He knows of what he speaks....

 

It wasnt my vette, but I had symptoms exactly like that on one of my other cars. After trying everything I could think of to no avail, I cleaned the grounds. Problem solved. If I were you, I would clean the grounds and see what happens. You might even have one disconnected.