Just finished up installing electric fans and harness. I have it pinned into the pcm. I was reading around and seen somebody say the fans should still come on and will always be on, until you get it tuned properly. Is this correct or will they not come on at all? Mine are not coming on.

 

If your truck didn't come with fans, I believe they are turned off in the tune. You could use a jumper wire to see if they function correctly.

 

What I came here to post.

 

Thats what i was thinking. My truck never came with them so i figured they wouldnt work with out a tune.

 

Bump. Still curious to hear what others have to say

 

They will not worked pinned into the pcm without a tune. You could hook them up to a switch but I recommend getting it tuned for fans

 

Ok. Thanks for the info. Ive heard on other forums people saying they'll turn on and stay on continuously, until its properly tuned. Sounds like those guys are wrong. Its getting tuned friday tho. So its hard to say if there hooked up correctly until then.

 

The outputs on the PCM are not configured until you tune it. Mine were off until I flashed the PCM ( I installed the fans, then flashed it with an update afterwards). If by chance one, or both of those outputs on your particular PCM are in the position to source a ground unconfigured.... the fans would then run constantly making that statement true. Mine weren't, and by the sounds of it neither are yours. You can ground the harness to check operation of the fans and your wiring. If they work and the pins are correctly seated in the connectors, you are good.