Testing PCM pin 42 - fan trigger
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Testing PCM pin 42 - fan trigger Hello,
I have a PCM out of a 2003 Chevy truck (6.0 gas). I am trying to see when pin 43 - blue connector comes on. I was told this is the pin for the fan relay and it is a negative trigger. I wired to a fan switch and the fan never came on... is there a way to see what it is programmed for or when it will / won’t come on with a scanner?
the prior owner hard wired the fan and I have confirmed the fan is triggered to come on with a ground to the relay, truck got up to about 220 / 230 and the fan didn’t kick on, so wondering if there is a way I can see what the computer does with that pin and when?
thanks for any thoughts you can provide.
I have a PCM out of a 2003 Chevy truck (6.0 gas). I am trying to see when pin 43 - blue connector comes on. I was told this is the pin for the fan relay and it is a negative trigger. I wired to a fan switch and the fan never came on... is there a way to see what it is programmed for or when it will / won’t come on with a scanner?
the prior owner hard wired the fan and I have confirmed the fan is triggered to come on with a ground to the relay, truck got up to about 220 / 230 and the fan didn’t kick on, so wondering if there is a way I can see what the computer does with that pin and when?
thanks for any thoughts you can provide.
TECH Senior Member
Joined: Jun 2016
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From: Central Cal.
You are correct. That ECM does not have the fan circuit activated. Electric fans came in trucks starting in 05.
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Thanks for the feedback everyone. I have reached out to the person who tuned my ECU to see if they are able to look it up in their system and ensure it is "off" before proceeding. I guess if they confirm it is off I just need to find someone in my area that can tune / edit the ECU and turn it "on"? Maybe they could download the tune so I could see what else is going on in there...
