05+ electric fan wiring
 

Hey,

Installing a 5.3 into a 91 rcsb c1500. I am using a psi harness and 02 pcm. I came across some 05 truck fans that I have mounted in. I however did not grab the factory harness for them. I have seen some aftermarket harnesses and such and read that the factory harness needed additional work for the ac trigger. But most of these were 99-04 guys mounting in there factory trucks. I am not running ac. In my situation if I can get the factory harness will it just be a matter of wiring it into the correct pcm pins and having the pcm tuned? Anything to be aware of for a basic install with no ac?

Thanks!

I have some Cadillac efans in my 2000 and a LS Performance Wiring harness and have them turned on in the tune.

Yes, if you find the stock harness its plug and play (minus repinning 2 wires which is no big deal) and then a tune. I did that to my 95 with an 01 PCM. I will be running A/C, but that is also no big deal just a relay to ground one of the wires when the A/C request kicks on.

You lose the auto recirc feature on the ac systems. Not running ac so you should be fine.... Just get factory harness and add the two pins to the pcm connectors and get tune to turn em on and youll be good...auto recirc just gave fresh air when ac was off, actually kind of annoying actually

Did you notice he is doing this in a 91? I think you are referring to 99+ trucks.

I made my own 2 relay harness for pretty cheap. both fans operate via pcm on high. I have no ac as well. But i noticed on mine that when i start the truck they are off for a few seconds thin come on. So i checked the wiring and the pcm is grounding the fans to come on. I thought mine was tuned for them. is that pin for fans automatically grounded when the pcm is not tuned for fans? I thought it was supposed to ground to turn them on. Mines is grounded as soon as it starts up.

Yes i did but pin for the recirc is still in the connector for the pcm.... Therfore he would still need pull the pin and swap in the pin for fan control.....

What are the pins # location for fans?

33 and 42 the diagram i am looking at saying both on ecm c2 but seem to remember having to connect 42 to c1 and 33 to c2

Ok thanks