Archived Dumfounded on PCM problem

[ABorchard]

What started out on a '95 3500 as no cruise control has escalated to no charge, tach, speedo and TC lockup. I would say bad engine speed sensor which is correct but no, the problem is no 8 volt supply from the PCM to the to the ESS.

Bad PCM right?

No, the PCM and another junkyard PCM work just fine in another truck just not on the problem truck. All the 12 volt inputs, outputs and grounds check out fine right at the PCM. The connector pins are straight. Only thing that doesn't work is the 8 and 5 volt PCM outputs measured right at the PCM.

I'm at a loss, dealer is at a loss.

Any ideas?

 

[Paychk]

The sockets (in the PCM harness) that the PCM pins seat into may have lost their grip on the PCM pins or there is a break in the wires between the PCM connector and the ESS?

 

[crabman]

Could be???

AB,

Check #4 pin on the PCM. It is the sensor ground for VSS, TPS, TTS, IAS, ESS and WIFS. All the above are spliced together, splice #S136. The splice is located between T/Os for Intake Air Heaters and Fuel Heater.

I am not sure if this is the problem but it could be. Please post your findings. I just :{ :-{} electrical problems!

crabman