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Discussion Starter #1
How do I turn on 2003 ecm fan controls?
I was told that a wire from pin 42 on Blue C1 ecm pin to fan relays would turn on my electric fans I put on my 2003 4.3. The fans are not cutting on, even set at 195 with 195 thermostat in, but I can do quick short to test circuit, and fans come on immediately.
Does anyone have any imput to help me solve problem?
Posted once in wrong place by mistake.
Thanks,
Ron
 

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From my reading in this for years. I believe it has to be tuned into the pcm. It’s not in programming by default


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Make sure the PCM is grounding the relay. It doesn't output 12V from the PCM pins, but rather it grounds them. So you want ignition 12V to the relay and use the PCM as the relay control ground.
 

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Discussion Starter #4
Yean, it has to be programmed, which I've been doing 15-20 years or so. Sometimes A/C settings of sort has to also be set. Not sure on S10. This is my first S10.
 

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Discussion Starter #5
Got fans going just fine. At 72, I made all my adjustments in ecm, and then forgot to save it. After going back through ecm with tunercat 2, I made my edits again, and SAVED changes this time, and all is well in Rocky Face. Fans work fine.
 
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