buddys truck died turns over but wont start gives no codes. using obd2 code reader glow plug light comes on for a second then goes off. try to start and nothing spinns but no start turns on switch no glow plug light wait a couple min. try to start glow light comes on.

 

Fuel solenoid driver, located on left side of the injector pump. Unplug the harness from the driver, plug in to a new driver, see if it starts.

This is the easiest way to diagnose that particular problem, they don't always throw any codes or check engine lights.