Installed new PCM, diagnostic link still says unable to communicate?

Tiny
PHILLIP GRAMOLINI
  • MEMBER
  • 1997 CHEVROLET TRUCK
  • 4.3L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 160,000 MILES
I put in a new programed PCM in my truck, and it still will not run, and the diagnostic link still says unable to communicate.
Saturday, August 20th, 2022 AT 9:31 AM

1 Reply

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,513 POSTS
Does the scanner work in another car? If so, let's check the AUX fuse #7 in the interior fuse panel, here are the wiring diagrams for the ALDL connector and the PCM so you can check the grounds and power leads, they will show you how the system works as well.

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

Check out the diagrams (below). Please let us know what you find. We are interested to see what it is.
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Saturday, August 20th, 2022 AT 4:08 PM

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