Random no charge, no tach, trans hot light

[DonFitzwater]

Just looking for confirmation of my suspicion..........or am I totally off base? I've been having a random
"Trans Temp" light and recently since temps have come up, the alternator will stop charging and tach doesn't register. I'm pretty sure the CPS is tango uniform but once it cools down and I test it, it tests ok and works fine........I know, I'm a sissy for not wanting to lean on that hot engine to test it while hot!!!!

 

[GAmes]

You don't have a CPS, the PCM doesn't care where the crankshaft or the camshaft is positioned. It is an engine speed sensor, regardless of how vendors label it. Did you check the gap to confirm it is .050 + or - .001? I've never had one fail from heat, or heard of it, but expansion/contraction might throw the gap out of wack. If that checks out I suggest you place some kind of heat shield between the exhaust manifold and the PCM. My guess is the PCM having issues.

 

[DonFitzwater]

I replaced the CPS (that's what it said on the parts bag so who am I to argue with the manufacturer of the part?) and now my truck is charging, indicating RPM and the trans temp light is off. Hopefully it stays that way.

 

[Harrison L. Root]

;my tach is intermittent. when it is not working the engine is in a reduced power mode. is this also the CPS?

 

[DonFitzwater]

You don't have a CPS, the PCM doesn't care where the crankshaft or the camshaft is positioned. It is an engine speed sensor, regardless of how vendors label it. Did you check the gap to confirm it is .050 + or - .001? I've never had one fail from heat, or heard of it, but expansion/contraction might throw the gap out of wack. If that checks out I suggest you place some kind of heat shield between the exhaust manifold and the PCM. My guess is the PCM having issues.

Hi Gary, well, old age of the truck reared it's ugly head during our 90 degree heat again. Truck had run fine since late March but the heat finally made the problem show up again. I sent the PCM to SIA electronics in Chicago and they rebuilt it for a whopping 126.00. They said the capacitors were popped and it had several broken solder joints on the board.