I recently purchased a 95 GMC Sierra 3500 with the 6.5L turbo for work/farm use. The truck started up great when I bought it. Then after stopping to get fuel after driving about 90 miles, and shutting the truck off, the truck wouldn't start. None of the indicator lights on the dash including the glow plug light would come on when i turned the ignition and therefore the truck wouldn't start. After sitting for about 45 minutes and multiple attempts of turning the ignition, the lights finally came on which allowed me to start the truck. This is the first diesel I've owned and new to them. Anybody have any ideas as to what's going on? Help would be greatly appreciated.

 

Could simply be the ignition switch going bad. I'd personally start with cleaning all the grounds and battery terminals. Inspect all the cables/wires. Load test the batteries.
Since your new to these trucks I'd advise doing a little research on this site about lift pump operation, pmd's, glow plugs. It will save you alot of headaches in the future.

 

Whats the best way to test all those possibilities?

 

Now the dash lights aren't turning on at all, the radio and headlights work just fine.