'95 Lesabre Electrical Problem?

[patrick_q]

Ok....where to start?
The car has about 40k original miles and ran great. My sister in law borrowed the car one weekend and it died on her. I went to pick it up off the side of the road where it left her and it wouldn't start, it would crant but wouldn't start. I towed it to a mechanic who said it was the crankshaft position sensor. He replaced it and it started.......this is where the gremlin came in.

He called me back a few minutes later and said that the car shut off on him again. he said he could start it and it might run for 5 minutes, it might run for an hour, but eventually it dies for no reason. It's also not throwing any codes.

He kept the car for about 4 weeks and on one of my weekly calls to him to get status he said that it is running fine. He said he couldn't chase an electrical problem when the car is not acting up. I picked the car up one night (after he had closed as I couldn't get there during the day) and drove the 50 miles home. It died on me 10 times during that trip and was doing very erratic things.

The speedo would jump all around, it would hesitate, sputter, lights on the dash would flash on and off, then the car would die. Everytime, however, I could put it in Neutral, start the car, and continue driving until it's next "seizure"

I made it home and talked to a few mechanics who all pointed to the Ignition switch. I replaced the ignition switch (which didn't fix the problem).

Here's the reason I think it's electrical....I can turn the key to the "on" position and dash lights come one, fuel pump engages, and then some of the lights on the dash go off and come back on and the fuel pump comes on again. Not all of the dash lights go off, the radio stays powered when this happens.

After trying to chase it, I discoverd that I can duplicate the problem by unplugging either the white or the red wiring harness from the PCM.

Does this mean the computer is bad?
Oh...I did check the battery terminals and connections, no corrosion

[imidazol97]

It might be the computer.

It might be electrical connectors called ground busses that are below the door sill plastic just where the front doors flatten out. You pull up that plastic where the A pillar plastic and bottom sill plastic come together and there will be a connector that could have 8-12 grounds slipped onto it. In climates where there's lots of moisture and salt tracked into the car on shoes, e.g., those connections can corrode.

Some people have kicked that area when a car won't start and caused a good connection again through the corrosion and found it started. You might try that backyard mechanic method.

But a computer or the spark connections at the plate under the coils might be suspect.

The dash lights might be related to a buss. Mine on a 92 would lose the door locks and the AC control would default to defrost and AC compressor on along with engine fans. I figured out it was the buss connection.

[Mickey#1]

Along with the ground buses check the ground under the ICM mounting bracket. The neg battery cable, ICM & I think the PCM (computer) still grounded there in 95. It does indeed sound like you have either an issue with power to the PCM or the PCM itself. I'd also check the connections at the PCM. If you try another PCM use the PROM from yours.

[patrick_q]

Update....Looks like the car is now fixed. I picked up a PCM from a U-Pull it place here in town for about $35 this morning. Went home at lunch and put it in and started the car. I let it run for about 20 minutes and it didn't even sputter. I then shut it off, and just turned the key to the 'on' position and the electrical stayed on for about 20 minutes and never cycled like it was before.