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Mike S.
Mike S., Chevy Mechanic
Category: Chevy
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Experience:  ASE Certified Master Technician
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1995 GMC: overdrive..anti lock brake oil pressure..pcm/ecm

Customer Question

I hit the brakes on my 1995 GMC Vandura 3/4 ton conversion van and the battery hit the metal frame and shorted out, the van died and I had to unstick the battery that was basically welded to the metal frame. I think it screwed up my PCM because now the van does not go into overdrive or drive, only runs in reverse, low 1 and low 2....also the anti lock brake light is coming on, it shows no oil pressure but the oil level is good and the passenger side window will not roll up without helping the motor by pushing the glass up. Where is the PCM/ECM located? I do not see it under the driver's seat like the Autozone people said....Do you think this is my problem? I thought it might be a shift sensor but that model evidently does not have one....was told it was probably the pcm.
Submitted: 6 years ago.
Category: Chevy
Expert:  Mike S. replied 6 years ago.

I would start with checking all the fuses, that is why they are there, to burn out before a part.

What is another name for the vandura? The model number?

Expert:  Mike S. replied 6 years ago.
What engine is it and is the tranny auto or manual?
Expert:  Mike S. replied 6 years ago.

For a 5.7L engines with automatic transmission, click here.

It appears to be under the drivers seat.

Customer: replied 5 years ago.
I replaced the PCM, it is behind the driver's seat. It did not help. The van drives fine until I try to use anything electrical if I get the speed up and get it in to overdrive first. Then I can use anything electrical. At night if I turn on the lights before getting my speed up, it will not shift into the higher gears. I have to put it in second gear and drive slow or find a place with enough light and space that I can get the speed up and let it shift into overdrive, then I can turn on the lights, etc. I was told on here that the contacts on the ignition switch might be the problem. I replaced it and it did not help. Any other ideas?
Expert:  Mike S. replied 5 years ago.

You might also want to check the alternator output, cause when the battery shorted out it could have blown up a diode or two inside the alternator. Did you also check the fuse for the transmission?

That is either the 1994-95 G-series gasoline engines with 4L60E transmission

or 4L80E transmission.


Customer: replied 5 years ago.
I replaced the alternator after I replaced the PCM, did not help. I am not sure about the transmission fuse though...will have a mechanic check it out.
Expert:  Mike S. replied 5 years ago.

I meant to check the alternator output in order to determine if that may have been a problem after the battery shorted out. Just replacing the alternator doesn't insure that the wiring to and from the alternator is still good.

The owners manual should tell you which fuse is for the transmission.

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