I have a 2003 Chevy Suburban. I pulled the efans and harness out of a 05 silverado. I pinned the green wire to pin 42 on the blue ecm plug and the blue wire to pin 33 of the green ecm plug. I have a diablo intune so I had someone who tunes diablo create me a custom tune and enable efan pcm control. Fans work correctly based on engine temp but will not cycle on for AC. If I start the truck up and turn ac on full blast, recirculate, fans will not come on till engine temp comes up and ac blows hot until fans cycle on. I've gone back and forth with the tuner. He sent me the below tune settings and said there is no setting for AC fan control. He says he has done tons of these and I either have a wiring issue or need to wire it to the ac clutch relay. I didn't splice any wires in the harness, just pinned the 2 in the ecm plugs. I find it hard to believe I have a wiring issue and it seems to me there is a limitation in the diablo tuner software. I do have a tech 2 and can command fan control on ac relay 1 and 2&3 and the fans come on. Any thoughts?


video below showing tech 2 fan operation.

 

If that is all that's available for you with Diablo you're missing a lot. This is what is available with HP Tuners. Find someone that has it to set up the fans. These are the stock fan settings from a 05 Silverado with a 5.3L.

 

So In HP tuners, these are the options I have for fans.

 

https://www.performancetrucks.net/forums/technical-write-ups-201/

 

You have HP Tuners running in Basic View. Set it to Advanced.

 

That was it, thanks everyone for the help. Fans are now working perfectly.

 

How would anyone, specifically HP Tuners, EVER think that "basic" view is A Good Idea?