Electrical problem
colemanr7
07-09-2004, 11:08 AM
Keywords: EBCM, Dash, ABS, 4wd, fuel guage, intermittent electrical problem, sierra, 1500, silverado, truck, computer
I'm posting this message in hope that it will help someone else to not go through the same headache that I have recently experienced.
The console display in my 1999 GMC Sierra began acting really strange a few months ago. At first, the "check engine light" came on but it quickly cleared itself and everything was fine. Later... the ABS and 4WD lights started coming on intermittently. My truck is not 4wd so this certainly raised my attention. The problem would clear and go away for a long time but then suddenly reappear. Things then got worse. The gas guage and the oil guage would intermittently drop to zero and then suddenly come back. The highlight on the "PRND321" indicator would disappear (not the lights... just the highlight) and then come back. The last symptom was intermittent "failure" of the speedometer. It would just drop to zero and then come back up really fast.
After reading on here and other places for a while I decided to disconnect the EBCM to see if it may be the culprit. Sure enough, the problem went away but (of course) the ABS light would come on since it wasn't connected. So... I sent the unit to a nice fellow (Gavin Curtis) to be repaired just in case it was the issue. He returned it promptly but alas it was not the problem. He was even so kind as to send another unit to me to test. Again... it didn't fix it. I would certainly recommend his service at www.circuitsolutions.info for issues that he mentions there.
So... I finally go the the GM dealership and pay the $70 to have it diagnosed. The recommendation was a new ignition switch assembly and to check some ground connections. The total cost (with labor) would be about $450. I decided to check the grounds myself first... but didn't really know where all of them were. I traced down all that I could find and reconnected them. No fix. I then ordered an AC/Delco ignition switch and replaced it myself. It didn't fix the problem. I returned to the dealership and discussed the issue again with the tech. This time he pointed out a specific ground point for my truck. I went home, re-did this particular ground connection and voila... it was fixed!
So... after all the hoopla, headaches, recommendations and non-repairs... the problem was a poorly connected fifty cent bolt. For anyone else having a similar problem, check this bolt first and other ground connections (including battery connections)! Look directly underneath the truck below the drivers-side door. Immediately to the rear of the front fender well there is a self-tapped bolt on a 1/8" plate with a ground wire. Disconnect it, clean it, apply dielectric grease, clean the mount point and go to the hardware and get a matching nut for the bolt. Put it back together and put the nut on the opposite side and tighten it all down really good.
I'm posting this message in hope that it will help someone else to not go through the same headache that I have recently experienced.
The console display in my 1999 GMC Sierra began acting really strange a few months ago. At first, the "check engine light" came on but it quickly cleared itself and everything was fine. Later... the ABS and 4WD lights started coming on intermittently. My truck is not 4wd so this certainly raised my attention. The problem would clear and go away for a long time but then suddenly reappear. Things then got worse. The gas guage and the oil guage would intermittently drop to zero and then suddenly come back. The highlight on the "PRND321" indicator would disappear (not the lights... just the highlight) and then come back. The last symptom was intermittent "failure" of the speedometer. It would just drop to zero and then come back up really fast.
After reading on here and other places for a while I decided to disconnect the EBCM to see if it may be the culprit. Sure enough, the problem went away but (of course) the ABS light would come on since it wasn't connected. So... I sent the unit to a nice fellow (Gavin Curtis) to be repaired just in case it was the issue. He returned it promptly but alas it was not the problem. He was even so kind as to send another unit to me to test. Again... it didn't fix it. I would certainly recommend his service at www.circuitsolutions.info for issues that he mentions there.
So... I finally go the the GM dealership and pay the $70 to have it diagnosed. The recommendation was a new ignition switch assembly and to check some ground connections. The total cost (with labor) would be about $450. I decided to check the grounds myself first... but didn't really know where all of them were. I traced down all that I could find and reconnected them. No fix. I then ordered an AC/Delco ignition switch and replaced it myself. It didn't fix the problem. I returned to the dealership and discussed the issue again with the tech. This time he pointed out a specific ground point for my truck. I went home, re-did this particular ground connection and voila... it was fixed!
So... after all the hoopla, headaches, recommendations and non-repairs... the problem was a poorly connected fifty cent bolt. For anyone else having a similar problem, check this bolt first and other ground connections (including battery connections)! Look directly underneath the truck below the drivers-side door. Immediately to the rear of the front fender well there is a self-tapped bolt on a 1/8" plate with a ground wire. Disconnect it, clean it, apply dielectric grease, clean the mount point and go to the hardware and get a matching nut for the bolt. Put it back together and put the nut on the opposite side and tighten it all down really good.
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