411 PCM Electric Fan Relay Clicking (w/ screenshots)

[garrinchilders]

2000 GMC Sonoma Swapped with LM7, Harness and PCM from 20001 Suburban. Dodge intrepid fans. Trying to set up a 2 relay setup for Fan 1 for first stage and Fan 2 for second stage. I have gone into the A/C tab and selected the Fan#2 control rather than A/c Recirc. I am attaching my wiring setup and the fan settings in the tune. When the low speed fan starts the relay starts clicking rapidly and the fan runs but at lower power due to it constantly cycling the relay, Click, Click, Click, etc. and the 2nd stage never engages, I can ground pin(s) 85 and the fan(s) run perfectly. I can even command them on individually via the VCM Scanner, but when the PCM calls for the fan organically, the trigger wires (from the PCM) pulse rapidly from Ground to (i think) open. and causes the fan relay to spaz out. Ive played with the temp settings and Nothing seems to change. I can find plenty of other posts with this issue but no one ever seems to post a definitive solutions, and seemingly no other posts indicate the actual trigger wires directly from the PCM alternating from ground to open. The wiring would have to be spot on for me to be able to command them on from the scanner, so i am leaning pretty hard on this being an issue with the tune that i just am not seeing. If I can get the PCM triggers to just output constant ground i think everything else should work. Hopefully.



*SOLVED My own stupidity or lack of sleep, I had set the trigger temps to 50f & 100f simply for quick wiring testing as I was originally messing around with this in my intermittent free time at work. I installed my fan harness in the parking lot after work and started the truck and the fan kicked on 3 seconds after startup, assuming all was well I slammed the hood and the drove home. I pulled in the driveway and shut if off and I heard the fan spin down, I again assumed success and went in to grab a shower. I came out and started the truck and popped the hood to check the second fan(s) operation since it was up to operating temp and noticed the clicking relay and no 2nd fan issue. Somewhere between installation and troubleshooting I had at some point changed the trigger temps to the correct values and saved the tune file AND NOT FLASHED IT. After a couple hours of troubleshooting and coming up stumped I went to bed and got up early and opened the laptop to post here for some help, I posted the screenshots from (what I THOUGHT was) the current file ON THE TRUCK, that I apparently never flashed & it never crossed my mind that the default disable temps would cause a loop if they were higher than trigger temps. <my own stupidity

Appreciate those who looked and attempted to assist. For the record The wiring diagram I made and the screenshots of the only pertinent fan command data of the tune file IS correct if it can help someone in the future.

[RDF1]

This is a good time to actually post your tune.

[blindsquirrel]

If you don't know how to fix it yourself, what makes you think you'd know the exact right section of the tune file to post a screenshot of?

[bk2life]

2000 GMC Sonoma Harness and PCM from 20001 Suburban. .

well theres your first issue
spend the money and buy the CPW wiring harness made for the swap, so its plug and play and everything works like it should, including your guages.

[garrinchilders]

This is a good time to actually post your tune.

^THIS^


My bad. I really should have. The fix was obvious once I reviewed the PULLED file from the truck. I had originally (for quick testing) simply lowered the trigger temps of both fans (to 50f & 100f) and left the disable temps the same (effectively causing a loop in the programming) and flashed it. Then corrected the values in the tune during troubleshooting and saved the file and never flashed the update, it never crossed my mind that the higher disable temps would cause a loop. So my wiring was correct which is why I could command them on with the scanner (PCM supplying uninterrupted ground without the disable temp calling for a loop). Just an oversight in the file. Appreciate the look anyway. Ill post tune next time. Lesson learned.

[garrinchilders]

If you don't know how to fix it yourself, what makes you think you'd know the exact right section of the tune file to post a screenshot of?

Oddly enough, I did end up fixing it myself. Just for my own curiosity, what other areas of the tune file would have been helpful to diagnose this remotely?

[garrinchilders]

well theres your first issue
spend the money and buy the CPW wiring harness made for the swap, so its plug and play and everything works like it should, including your guages.

Wiring is kind of something I enjoy doing. I started with the OEM Suburban harness and de-pinned EVERY. SINGLE. PIN. from every cavity on both PCM connectors labeled them and strung them up on a wall. then I used the fancy (chinese finger trap) loom (like CPW does on their upgrades) and restrung every circuit to its new location in the Sonoma engine bay. So it was effective plug n play sort of just things in new locations. It's uses the factory plastic hold-down clips, I can unplug and remove harness like factory if need be. Its all factory color so trouble shooting is easy. Everything works, No warning lights. All gauges work as they should. & I didn't speed $950+ on something I was more than capable of doing on my own.