1990 Chevy 1500 Starter Wiring Diagram. The first pic looks to definitely be to your coolant temp sending unit which should be right there in the head. Each component ought to be placed and linked to other parts in particular way.
Check your ground wires out. Ignition system circuit diagram 1992 1995 chevy gmc pick up and suv. 1990 gmc c1500 tailights electrical problem v8 two.