while driving my truck the tach will quit working, it starts discharging, the air conditioning will quit working, and it will shift out of overdrive all at the same time. This condition might last a few minutes or all day long. Would defintely appreciate any input from any one. Thanks. 1993 Ram 250 4x4 with 70,000 miles. BANKS kit with bigger turbo, bigger inter cooler, fuel pressure turned up slightly, B&D torque convertor, reworked vavle body in transmission, no muffler in exhaust, lifted slightly with 35 inch tires. THANKS!

 

Sounds like your pcm is losing power or ground. I'm not familiar with the 93 model but would start by checking all grounds and connectors for corrosion.

 

Sounds Like A Bad Crank Position Sensor Or Pcm I Would Try Cps First

 

check your wires to and from the crank sensor to the pcm make sure they are not rubbing any were mine were rubbing on the shut down solenoid oh and clean the crank sensor it could be dirty

 

On a 94 I had this happened and was bad crank position sensor. Most electrical went out.

 

Like the other guys said, classic crank sensor symptoms. The wires are vulnerable where they go by the fan belt, and they often get chafed where they go over the front of the head. There's a connector on the font of the engine that could be cruddy too. Also check to be sure the sensor is tight and that the gap is 0.050" or a touch tighter. Use a non-ferrous feeler for the check, a folded over matchbook cover works OK.