02 2500 with 6.0. Using Nelson harness. One fan comes on when AC is turned on. Cannot get other fan to come on with engine temp. My tuner turned on the fans with an 05 file. Computer thinks they are coming on. I am using pin 42 as per instructions. No one at Nelson answers the phone. I cleaned the connections just to be sure the pin was making good contact. I replaced the fan motor with a known good motor (tested). What voltage should I have from the blue wire (pin 42) when computer signals fans to come on? I have no voltage, but cannot figure out why.
Scott

 

The PCM doesn't put voltage out of the fan wire, it grounds it when its on. Take a small light bulb or your test light and put one side on 12 volts and hook the other side to that PCM output it should light up when the fan is suppose to be one