Very strange electrical problem
Thread Starter
Racer
Joined: May 2000
Posts: 322
Likes: 1
From: Manchester TN
Very strange electrical problem
I posted an earlier topic about a possible problem with my VATS or neutral safety switch. When you turn the key to start the car, nothing happens. The ABS light strobes and the pump pulses with the key in the on position. When I jumper A-B to go into the diagnostic mode, the cooling fans do not come on. The relays just start clicking and the service engine soon light flashes along with them. This made me suspect the ECM. I tried replacing the ECM but it behaved the same way. I am at a total loss. This happened after I took it to the local garage to reconnect some ground wires that had broken when I rebuilt the engine. They told me that after they had hooked up with my computer, they discovered that there were several codes stored that were not tripping the ses light.
Please help!
Please help!
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
there is no easy fix here, buddy... you need the right book, the right tools and a lot of time.
get a good DVM and a test light.
Most of the interior/dash grounds are on the 2 kick panels (each side). Start there and work back, but to do that, you WILL NEED THE HELM MANUAL. It's expensive, sure, about $100.00 for the set, but the VALUE is priceless.
get a good DVM and a test light.
Most of the interior/dash grounds are on the 2 kick panels (each side). Start there and work back, but to do that, you WILL NEED THE HELM MANUAL. It's expensive, sure, about $100.00 for the set, but the VALUE is priceless.
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
The ECM grounds the fan relay coil to turn on the fans. Part of your problem has to be a poor ground for the ECM. Also, I would check out the quality of the battery ground. On my 87 the battery grounds in two places (don't know about the 91), on the LH side of the engine below the LH valve cover and on the frame by the RH side of the engine. You should get the GM repair manual and the electrical diagnosis manual for your year and check the quality of the ground/s of the battery and the ECM.
