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How do you determine if your PCM is the problem (short of changing it out)?
Also, might it be possible that I damaged it by grounding the self-test output instead of the input? I was trying to do a KOEO test by memory and instead of running a jumper from the STI to the ground terminal, I ran a wire from the STO terminal to the ground. Maybe just coincidence, but now the motor won't run.
How do you determine if your PCM is the problem (short of changing it out)?
A common way to spot a bad PCM (and the way I concluded mine was bad) is a visual inspection. The capacitors leak. My truck bucked violently. I inspected my PCM, noticed a leaky capacitor, replaced the PCM, and bucking went away. I don't know of a way to determine 100% other than sending it off to be tested.
Well I went and bought a OBD1 Ford scanner, and according to it there is nothing wrong: got the 111 pass code and then the 10 code to show it was finished with KOEO cycle.
I wonder, would the engine have to have been actually running at some point to get codes thrown on the PCM, or would they get stored during my failed attempts to start while engine is cranking? After all, this is now a different PCM, so if codes aren't thrown during crank cycle then I'm assuming I'm just reading the pass code from the previous donor truck.
The KOEO codes before the 10 are electrical tests and are the same if it had run or not.
This KOEO test before the 10 is for continuity and to see if all the readings for the solenoids and sensors are in the ball park values of what they should be.
The codes after the 10 in the KOEO self test are the codes that are lost with the power being removed from the PCM.
These codes are for anything that did not go right on the road.
OK, so sounds like there won't be any codes after the 10 until the motor is actually running, which in this case is the problem I'm trying to diagnose! D'OH!
PCM troubleshoot?
back at it
