All at once my truck shifted out of o/d and no speedometer.... plus i lost cruse a few monts ago and my a/c quit working the day my speedo quit.... i dont understand!! I replaced the speed sensor still nothing... checked fuses and all my tps stuff... i dont know what to do and i have a trip this weekend!!

 

My problem was the VSS (Vehicle Speed Sensor). Lost O/D and speedo.. Cruise hasn't worked in a long time.. and neither has my A/C, I'm guessing your A/C issue is not related to your speedo and O/D issue.

 

My a/c works now... and i replaced the speed sensor and checked the gear that turns it... still nothing... i grounded my overdrive solenoid so i can drive it till i fix the real problem...

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Anything else that i could do to trace the problem down?

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In my experience, if the VSS isn't the culprit, it's the PCM. This is so common it's unreal.

 

The computer?

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Yeah, PCM=powertrain control module=computer. It controls very little; the speedometer/overdrive, the air conditioning, voltage regulation from the alternator, and grid and fuel filter heaters.

Decomputerizing it is an option. I'm elbow-deep in a Cummins Ramcharger swap and I'm deleting the PCM.

 

But everything else works... even the grid heater... is it common for just one thing to go out?

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Yep. The PCM in my 91.5 refuses to have anything to do with the speedometer but everything else works. Right this moment a GPS is my speedo and o/d is on a switch.

 

Will a gas burner pcm work on my truck?

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