no spark

[Erik the Awful]

Use a test light and backprobe the power wire going into your ECM before you try swapping it. Check that ground wire as well.

 

[Schurkey]

Checked all fuses replaced crank sensor and icm again. Just going to order a brain hope that fixes it

This is not a great procedure. Diagnose, then replace.

Use a test light and backprobe the power wire going into your ECM before you try swapping it. Check that ground wire as well.

What kind of "Test Light" did you use? If it's the old, incandescent-bulb style, I suspect you'd get no flashing. A "Logic Probe" would be more appropriate because it wouldn't produce an excessive load on the system.

As usual, an actual scan tool would be best.

Connect scan tool, look for rpm when cranking.

 

[Relenting]

Reman PCM came in swaped it in truck fired up on first try. Thanks for all the help

 

[knarf]

Checked all fuses replaced crank sensor and icm again. Just going to order a brain hope that fixes it

So did you replace the brain and what was the outcome?

 

[Caman96]

So did you replace the brain and what was the outcome?

Reman PCM came in swaped it in truck fired up on first try.

 

[knarf]

I think I may have to do that but I will swap out the old and re-pin out a 0411.

 

[scott2093]

Not sure where to ask but, when a (1993 GMC Yukon for example) PCM is remanufactured, anyone know what they actually do? Not the prom obviously but, are there known failure prone components on these PCM boards? Lot of stuff in there for sure.
With some of the janky oem reman stuff floating around it almost seems like finding a decent donor with a computer would be a safer bet??
repairing or Upgrading electronics is obviously better if done right I'd guess but is it better than what came from factory quality control?/

It's also hard to wrap my head around the fact that a pcm from a 4.3 Astro Van has the same computer as my truck. I guess pinouts are same? Or does the prom just know how to direct traffic...
Wonder if pinouts are same.....