Having fun with a no cold start situation.....plug the block heater in and she fires up in one revolution of the engine.

Thought the PCM might been misbehaving as far as the GP cycles go...did some probing around and found the ground pin in the plug to the controller is NG...open circuit somewhere down the line. Spliced in a new ground, installed new made in USA controller/relay, lite comes on, ....no start. Got crazy and let it crank for about 15-20 seconds and she made her own heat and started. Ran perfect upon starting, no codes, no issues.

Noticed some other anomilies..Voltage really doesnt take a hit like it used to when the GP relay is activated. Ran another heavy gage wire to the controller.... rule out bad wire ...probably not.

Put an amp clamp on the input side...only drawing 50 amps upon relay activation, GMC manual says 100 amp minimum draw for the GP's

Have my multimeter on the GP's ...ground to engine... probe on GP spade..zero resistance on 2 so far on the drivers side...

Question...what is a good resistance value for these quick-heat GP's...?? Ballpark is fine....anything but zero??

Thanks