So there you go. The PCM is not responding. I was gonig to suggest you do whatever is needed to obtain the fault codes, and if that procedure doesn’t work, then the PCM is not responding. Often that is a flashing check engine light on OBD I. It could be a ground fault. It could be that a relay that powers it is faulty.
Failing capacitors and clock resonator crystals are common in older electronics. If it is getting Voltage at the proper inputs but it is not responding then there is a problem inside the PCM.
OK…Now I’m gonna ask a stupid question…Where is this ?
Is the PCM the same as " PowerTrain Control Module RELAY "
I see in rock auto…(trying to get a visual)… for the 1995 Mercury Sable 3.8L…That the “Computer Control Relay” looks just like the “Powertrain Control Module Relay”
For fun… I unhooked what this looked like (pretty much on the driver side of the radiator near the top (close to the hood when shut))… did NOT get high fans…and I don’t think I got the fuel pump 2 second run either…
OK…I call that the ECM…already changed it out with a used one…pins had looked good…
sigh…Just wish it would stay broken or stay fixed… i HATE intermittents …
The PCM is the same thing as the powertrain control module. It’s a computer circuit board with a lot of connectors. Unlikely “PCM” and the “PCM relay” are the same part.