I'have a 94 2500 with an intermittant problem.Sometimes when I start the truck (cold or hot),the dash is completely dead,(none of the guages work)and it's not charging. Everything else works. Other times when I start it everything works and it charges. I have checked all fuses and grounds and they seem good. Any ideas?

 

Sounds like the engine speed sensor is failing or the wiring, connectors to it are loose/corroded/cut.
Sensor gap could also be wrong.
The sensor is located the dampener (lower engine pulley).
Check the wires from it for damage. Make sure the connector is tight and clean.
Gap should be about the thickness of a business card.

The engine speed sensor tells the PCM (computer) if the engine is running or not. If a fault tells the PCM the engine is off nothing electronic will work.

 

i have a 97 that does a simialar thing at start up the truck will fluxuate chargingvoltage from 12.3 to 14.7 voltsuntil the truck warms up then runs 14.7 volts. iveadjusted the engine speed sensor from .30 to .75'' nothinchanges it all other functions work fine

 

Normal, it's your grid heaters switching on and off.