I am trying to help my buddy swap the pcm in his 2005 Yukon. The stock Yukon pcm is no longer calling for fans to come on when up to temp or when the AC is turned on. We have checked and replaced every fuse and relay, (none were bad but replaced anyway) and replaced the temp sensor. Still no call for fans. When connected to the snap on scanner and sending a call for fans to come on they do not come on but if we jumper the relay they do come on so we know the fan wiring is good. We have pulled the fuse box and looked for corrosion and burnt wires as well and everything looks good. We are at the point where we believe the pcm is the issue. We got a pcm from a 2005 Avalanche, same OS and turned VATS off. When we connected it the the Yukon it will start and run but the idle is very low and it stalls out when coming to a stop. We are able to get it to trigger fans to come on through the snap on scanner but it will not run long enough to get it up to temp to see if they come on with a call from the pcm. Also, the traction control comes on and will not turn off, the cluster says something about stability control too and it feels like it has no power. I did a compare of the old file to the new and transferred over differences to the new file. I have not had a chance to try the computer again but does this sound like it should fix the issue on the new pcm? am I missing anything?
Again. I am new and trying to figure things out so I apologize if I'm leaving any details out, any help would be great.
The Yukon file is from the "bad" pcm the Avalanche file is the "good" pcm.
Last edited by Markrose76; 02-10-2023 at 07:49 PM.
Both those vehicles use the same PCM. If it was me I would just write entire the Yukon file to the Avalanche PCM. Then do the 30 minute VATS relearn and retain the VATS.
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