I am very interested in following this. I have a 2015 Yukon XL and have replaced the TCS three times.
It is intermittent. Will run for a few weeks and then the temp goes to 0 and fan runs. Then it will go another week. Seems like it happens more when driving on surface streets.
Can the wiring harness be replaced without removing an entire harness? Where can I check the resistance up the line further.
Someone mentioned the ECM, where is that at? Just real frustrated I can't fix this!