My truck is a 1989 GMC Sierra Extended Cab.The reason I posted was because a screw driver slipped & hit the grd & ignition post of my solenoid for my dual battery set up. Since then my aux battery would not charge. I then checked the voltage at ign post of this solenoid & noticed no voltage coming from it. I then put a jumper wire from the main battery post of the solenoid to the small ign post & then checked the acc battery post voltage & it registered 0v & no continuity between the main battery post & the acc battery post. So I must have shorted it out. I investigated it more & took some voltage tests at the connector for the ignition harness. My findings were:
12V CONSTANT WIRE RED there was no red but white. In acc,it gave me 12.8v, with the engine running it gave 14.5v
STARTER WIRE YELLOW OR PURPLE-the purple wire gave me 0.03v while in acc, with the engine running it gave me 0.71v
IGNITION WIRE PINK-in acc. it gave me 0.03v, while the engine was running it gave me 0.70v
ACCESSORY WIRE ORANGE-in acc it gave me 0.03v, while the engine was running it gave me 0.72v
Gray wire?-in acc this wire gave me 0.03v, while the engine was running it gave me 0.70v

I'm not sure if these are normal readings for the ignition? Are these good? Does anybody know what the gray wire is for? Looking at the wiring diagram the pink wire has a 3amp fuse before it hits the engine control module then to the coil- the white wire goes to the battery & the purple one goes to the starter. I do not know where the gray one goes unless this is the tach, sort of confused with the white & gray wire as the diagram shows the white wire as the tach. coming out of the coil. Just wondering if these readings are normal or did the solenoid create other problems? Any help on this would be much apprieciated. Thanks.