Does anyone have a GM service manual for a 88 GMC K1500 5.7L 4X4?
88-94 body style.

I would like to get wiring schematics of the HVAC system, and the 4WD system, particularly the actuator motor to see if it's getting a signal.

Or - if you know where I can purchase the schematics, that would be helpful too.
Need them ASAP. Working on his turd tomorrow.

1. Heater suddenly blows 25 amp fuses
2. 4WD will not go into 4WD - at all. No light, no engagement.
Both worked fine in the morning, went home, parked it, got back in it hours later, nothing.
Need to finger it out, but can't do it in the dark.
Autozone only has generic schematics that don't help with either of my issues.

Let me know if anybody has them, or where I can purchase them.
Thanks