1997 TransSport PCM Failure

Can the PCM have a partial failure and not set a fault code? I'm having an A/C-radiator fan control problem and the dealer says it's a bad PCM. I had it in for a bad A/C compressor clutch replacement that I knew was bad. Does this sound bogus? I've replaced all of the fan relays already and no help. The van runs fine otherwise.

Get a second opinion. I would be more inclined to think that the fan motor has gone bad not the PCM although it does control when the fan activates. Before replacing it try to replace the fan temp sensor and if you find that doesn't work then purchase a used PCM from a wrecking yard for the same vehicle and replace it yourself. This will save you some major dollars both in parts and labor.

I agree with GTP Dad. It's possible that the PCM has gone bad, but not very likely. Take it to an independent shop for a second opinion.

Thanks for the replies. I decided to have the PCM replaced, as I've been having intermittent fan contol problems that were not corrected by replacing the temp sensor. A plugin harness test showed that the circuit from the PCM to the fans was working properly when false signals were sent. Both fans acted at low and high speed when commanded. Usually the most I would get was low speed when the temp guage hit around 210, and full speed with the A/C on. Looking through the GM service manual for the van leades me to believe that the PCM can have component failures for specific circuits and not set a code, and that seemingly unrelated systems can have weird effects on each other when something goes belly-up. The van was hit on the left front fender where the PCM is located last year, and maybe it finally gave up the ghost. Either that, or someone fried it at the dealer and made up a BS story to cover his butt. I asked for the old core and the failure printout just in case.