I have a 95 4x4 2500 (no EGR)
I have been troubleshooting a boost control issue and found no voltage across the vacuum solenoid. I have 12volts at the red lead and when I ground out the yellow lead the solenoid activates. Before I start taking the wiring harness apart, do I have a bad ground? Is the solenoid controlled via the yellow lead (common 12volts) or controlled via the red lead (common ground)?
Where could I get a decent wiring diagram? My Haynes book is not very helpful as it is geared to gas engines.

Thanks BERT