Cooling Fan PCM Grounding
02-25-2015, 08:22 PM
#1
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Join Date: Aug 2013
Location: Brentwood, CA (The Northern CA Brentwood)
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Cooling Fan PCM Grounding 1998 Z28. Cooling fans stopped working. I have narrowed it down to: a bad ECT sensor, a bad wire from the sensor to PCM, or a bad PCM. Going to switch out the sensor and do a continuity check on the sensor wires tomorrow. I have physically unplugged the fan relay signal wires from the PCM and grounded them and the fans work. My question is: all of the fan wiring diagrams show the PCM grounding the fan wiring system to activate the fans after receiving a signal from the ECT sensor, is the grounding actually done internal in the PCM or is there another relay somewhere that physically does the ground switching?
03-11-2015, 06:12 PM
#2
I can't say 100% on your 98 but I can share that I just hooked up the electric fan to the ECM in the Jeep(2000 truck harness and ECM) and it was only one wire to the ECM for the hot/positive to turn on the fan relay and everything else grounded elsewhere.