GM-GMC: My truck wont start, gm diesels, electronic engine control

Question
My 96 GMC 1500 series diesel has been running great lately...it ran all day tday for my dad and then tonight when i went to turn it on i tried starting it and the starter turned over but i had forgtten to let the glow plugs warm up so i stop tyring to start it...and then once i had let the glow plugs warm up i tried again to start it and it wouldnt even turn over...i checked the battery and it was fine..what cuold be wrng?

Answer
I hope that you checked both batteries, as GM diesels use two start batteries.

There are many possible reasons that the vehicle failed to start.  Batteries that are marginal, loose or corroded battery connections, a worn out starter, defective glow plugs, glow plug controller problems, electronic engine control problems, etc.

It is likely that you cranked the engine and reduced the battery power to the point where turning on the glow plugs (which draw 100 Amps hwen first turned on) pulled them down to the point where they could not start the engine.

Try charging the batteries and check all battery and ground connections.