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1994 S-10 Blazer 4.3 PCM location

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New User

Sep 18, 2005, 2:23 PM

Post #1 of 3 (3773 views)
post icon 1994 S-10 Blazer 4.3 PCM location Sign In

I've pulled a code 51 which in the Haynes manual indicates a prom chip problem. In my experience this is not the case unless it's an altered or after market chip. Usually a bad ground either PCM case itself to ground or somewhere close. Question: Where is the damn thing? Do I have to pull the complete dash apart?Crazy

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DanD profile image

Sep 19, 2005, 4:31 AM

Post #2 of 3 (3756 views)
Re: 1994 S-10 Blazer 4.3 PCM location Sign In

It’s under the right side of the dash, if you still can’t see it after removing the lower insulating pad try removing the glove box.
The PCM case isn’t actually externally grounded, as in a wire or strap connected to the case. It gets its ground through terminals A1 a black/white wire and terminal A2 a tan/white wire of the PCM red connector. Their main connection to ground is on the rear of the left cylinder head.
There is a splice in the harness somewhere that the black/white branches out and connects to the rear of the right head.
After you have checked the grounds, open the access panel of the PCM make sure the that the PROM is plugged in correctly and that there are no bent or loose pins.
Call the dealer with the number you’ll find on the PROM there maybe and updated unit that relates to this and other drive ability problems.
Good luck, Proms are becoming harder to find since they went to a programmable PCM

Canadian "EH"

New User

Sep 21, 2005, 12:10 PM

Post #3 of 3 (3743 views)
Re: 1994 S-10 Blazer 4.3 PCM location Sign In

Thanks a bunch Dan!
This is the first chance I've had to get back to so I'll follow your "flow chart". I don't think the prom is loose cuz this hasn't been touched. I actually inherited this beater from my young daughter who was terrified of driving it after a certain incident. The only problems are pretty well documented in this and other auto forums i.e. sticky (and exspensive) EGR, lousey brakes I'm sure you've heard it all. Decent engine. Thanks again. Evan

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