Here's a picture of the VCM in my program.

 

Wilde, do you have another PCM you can swap in to rule that out as the problem?

 

By physically grounding the pin you've ruled out the harness. It would have to be a PCM issue or the pin physically not making contact. AFAIK all 03+ Os's have the capability so not that IMO.

I don't remember any issues when I commanded the fans with HPT. I do know that for them to work in HIGH both pins 42 AND 33 must be grounded. Try commanding both low and high speeds at same time?

 

you have to set the settings for the fan in the tune like an 05. i had the SAME issue. when they released the ability to have a/c control for the fans i didn't set the settings. so i was driving along pulling a trailer uphill and started over heating. i freaked out checked everything. then i went into the tune and set the settings. after that i was able to control the fans too. i just made mine identical to a 05 besides my temps.

 

Yep, and it didnt fix it..

I also tried falshing a complete different 2500 file in it, and 1500HD. both did not alow control over the fans.


I tried both settings (aux and 2-fan) I also tried using the exact settings as Truckshop. as his works.

I just think the 03 2500 is unable to control pin 33

 

Hmmm, I haven't heard of a 2500 using both pins 42 and 33 now that you mention it, sounds like you found the issue. I'm guessing that the 2500 PCM doesn't have a ground on that terminal, so even if you flashed in 1500 settings it probably wouldn't work

 

Never mind, turns out after two days of screwing with this and countless times of removing the pins from the PCM connector. I had them both in pin 42 locations. Move the wire to the actual pin 33. all works as it should. Thank you all for the help, but there is no help that will work when helping the helpless.... or is that hopeless?

What a dumb ***.....

 

glad to see ya fixed it.

 

Lol! Don't ya hate that.
Glad to hear you found the issue.

 

LOL, glad you got it working man