View Full Version : 12216125 xdf help for E-Fans

01-18-2021, 06:40 PM
Hello all. I'm fairly new with playing around with the ls platform stuff as I used to work in the import world. I have installed e-fans on my 2002 Suburban. So far the fans work based off the temperature that I input into tuner pro but the A/C does not activate the fans. I have read that I need to change the A/C type from analog cycling to analog for the pcm to recognize the new pressure sensor I installed. I can't seem to find an XDF that has A/C type defined or the hex address so that I could change it. I do have a hex editor as I used to burn chips for Mitsubishi's back before you could flash. I don't know how to dissect code so I can't just find it myself. Any help would be much appreciated.


dave w
01-19-2021, 06:44 AM
Are you open to the idea of a "non-code" AC "on" relay solution? See attached. Maybe DIY with information in the .pdf?

dave w

01-19-2021, 05:34 PM
Originally I was going to just use a diode and the A/C compressor relay trigger wire to activate the second fan but came across this thread https://www.performancetrucks.net/forums/technical-write-ups-201/electric-fans-2002-1500hd-proper-c-control-553385/ and decided I wanted everything to work like stock. If I can't find someone to help define A/C type then I will have to use my original plan until I get my cam and lifters installed and go to have it tuned. HP tuners has the ability to change the AC type. I know it can be done it Tuner Pro as people have done it with other bins. The OS 12212156 bin has a XDF with the AC type defined so I had hoped that someone who knows their way around these bins could help me out. I've discovered that it appears to only need two bytes changed in the bin for it to work. Figuring out which ones and there location is where I'm lost.


01-20-2021, 03:34 AM
I gave up on PCM control of my fans and went with a pair of Four Seasons part number 35879 fan controller kits. Very easy and dependable.

Sometimes, I just want to drive and enjoy my ride . . . and not tinker.


01-22-2021, 12:51 AM
With the help of some guys over at pcmhacking.net I was able to get this figured out. If anyone else with a flex-fuel 12216125 os is looking to do the E-fan swap or wants the PCM to control everything like stock and use tunerpro then the address for the A/C type is 0x1EFDA. That needs to be changed from 03 to 02 then you use Universal Patcher to make sure all your checksums are correct. The rest is all defined in the xdf for tunerpro and you can change the settings to what you like. You will need to add a 3 wire pressure sensor wired into C2-14 for the signal wire and then find a 5v reference and a reference ground. I used the EGR since my vehicle didn't have EGR. Everything works like stock. The low fans cycle on and off with A/C pressure and the high fans come on if the pressure gets to high.

dave w
01-22-2021, 05:00 PM
Thank you for sharing :thumbsup:

dave w

01-24-2021, 05:01 AM
Kool, storing this in the "good to know" department file!