Hey everyone, I'm looking for help with my P0483 fan rationality check issue. I replaced the fan clutch, swapped the relay with known good from another truck, replaced the ECT, cleaned the grounds and they ohm out under .5, I have 12V and the two signal 5v all at the 5-pin plug. Upon start up the fan stays with the engine idle rpm and is pushing but when revved up a time or two it slows down and I can stop the fan in place with the engine running. Used the power probe ECT3000 and traced the wiring all the way back to the ECM and it checks out with no corrosion. Just curious if anyone else has run into this issue? I'm not sure whether to suspect a faulty part or if the ECM is the culprit. I've plugged in my Snap-On solus and tried to engage the fan through it but nothing changes. Any help would be appreciated. Thank you in advance!
2015 LML P0483 Issue
- Thread starter JohnS
- Start date
I appreciate the info Ron and will look into those areas. I've probed the wires back to the ECM through the wiring harness already which lead me to think its either the ECM or a bad replacement part.
Connector info attached. Is the speed control a PWM signal? Is this the part you replaced
GM Genuine Parts 25845280 Engine Cooling Fan Module
Question for you Ron. I back probed (White) Cooling Fan Control Signal. Had zero volts when I first plugged in until I heated the motor up to 210 degrees then got my 13.84v with no cooling fan engagement. Shouldn't the fan engage at that point? Grey/Red has the 5v signal, the ground is good from the harness to engine block. I did check the ground signal coming back out of the fan clutch to see if it completes the circuit at its zero volts when back probed within a few seconds of verifying the 12v to the white control signal wire. I'm assuming a bad fan clutch from the distributor that I replaced when I first had the issue. Thanks for your help.
Unfortunately not oem. Bought this for a replacement clutch thinking my truck would be such a snowflake and sensative.
Attachments
Wouldn’t even waste your time trying to diag it. We’ve seen this at work a few times.
Wish I could find the Instagram reel I watched not too long ago on a cummins oem vs aftermarket thermoelectric clutch. The aftermarket does not use the correct fluid, no where near as many vanes and the clearances inside are far too loose not sending the oil where it needs to when you turn the fan “on”.
So when the truck turns the fan on and it sees that the fan is not matching engine rpm within its range, you get this code.
Wish I could find the Instagram reel I watched not too long ago on a cummins oem vs aftermarket thermoelectric clutch. The aftermarket does not use the correct fluid, no where near as many vanes and the clearances inside are far too loose not sending the oil where it needs to when you turn the fan “on”.
So when the truck turns the fan on and it sees that the fan is not matching engine rpm within its range, you get this code.
Really!? I can stop it with my hand while the engine is running after I pump the throttle a few times. Is this why I see so many threads wanting to convert the clutch to another option? It's worked great till 101,000 mi then it popped up. I scheduled an appointment with the dealer on Monday but I feel ill get the "it's this" "then it's that" bs!
I’d listen to James Chevy1925, he actually owns this site and has more knowledge than most on here. Plus, he actually works on them daily.
Yeah not good, specially if it’s commanded on. Also, would NOT recommend doing that with a gm one lol.
It’s still possible you may have an issue with something else but we gotta start with a known good part
Thank you for saving me the money going to the dealer. I replaced the clutch last night with the GM clutch. I got an immediate response and its acting as it should. No CEL and back to normal on these hot days! Sending the pos clutch back to parts geek. Thanks again bud!
I'm glad this turned out OK. For everyone else, you might try some folded-up newspaper so that you don't lose any fingers or your hand.
Haha. Probably right. I'm a field mechanic working on heavy equipment. Something just didn't seem right when the fan slowed down and could tell it was just spinning off of centrifugal force. Thanks for the wiring diagrams Ron!