The digital temp control on my 05 limited is going haywire. At times it will randomly start adjusting the temperature up. Works fine then all of a sudden i see the numbers changing by itself. Couple weeks ago i started getting a battery light which was being caused by a bad alternator. I figured the low voltage was causing some things to go crazy so i didnt think about the temp control issue too much. I replaced the alternator, battery light went away but the temp control still had an issue. I bought a refurbished "guaranteed tested" EATCH unit and swap it in, still has the same issue. Ive searched and searched on google and couldnt find anything on this.

Could it be possibly related to GEM module issues? I do have annoying power locks that unlock themselves at random. I also have the wierd issue with the cluster relay that wonks out when the headlights and climate control are running at the same time. I hear it clicking sometimes when i turn the wheel. Any ideas?

This virtually renders the truck undriveable. Its much too hot to be driving without A/C right now. Even when it was working correctly i have to keep the a/c on the full blast to even hope to keep the truck cool.

 

You said you have an 05 limited Excursion, and weird things happen when you turn the steering wheel. My 05 limited has temperature control adjustment buttons on the steering wheel where you can increase or decrease temperature and change the fan speed. I'm betting your steering wheel clock spring is broken and the EATC unit is responding to inputs from the steering wheel controls.
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you know what, i hadnt thought of that. My clock spring is definately broken cause the cruise control doesnt work either. I'll try to swap in a new clock spring and see if that fixes it

 

You could also try unplugging the connections that lead to the steering wheel controls and see if that fixes the random changing temperature issue. That would at least confirm the clock spring as the culprit.
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good thinking... thanks

 

Very reasonable suspicion. I have a problem with the steering wheel controls on mine too. When I press volume up, sometimes it changes the radio mode instead and volume down does volume up. Same issue basically.

 

I can state with 100% confidence that it's not the GEM module since a 2005 Excursion doesn't have one.

Sounds like either the power to the EATC isn't quite enough for what it needs in the way of power to be happy or it has a bad ground. First thing I'd do is evaluate the performance of that replacement alternator to ensure it's putting out what it's supposed to. I'd also load test the battery.

Eh, what relay is that, exactly? There's nothing officially named a "cluster relay".

 

Probably this....?
https://circuitboardmedics.com/2002-...luster-repair/