Trans Temp Gauge 2001 Yukon

[Moosemoon]

The Transmission Temp Gauge on the dash jumps all over. It appears to jump to a what seems to be a legitimate temp then bounces down and up and so it goes. After a while it does seem to get to temp and stay there. The gauge cluster has been replaced but I think I was told that the Trans Temp Gauge isn’t part of that.‍
It seems to react to accelerator pressure and release and brake pedal pressure and release. But I am not convinced that is true.
I did have an aftermarket trailer brake installed. According to the documentation the Yukon came with the wiring harness for the trailer brake but I have no idea if the installer used it.
If memory serves me right (not guaranteed) the gauge was fine until the trailer brake was installed. The trailer brake under use does not work correctly but the installer says all the electrical tests as it should.
I had it in more than once - they seemed to have the gauge working for a while but not now. There is no time left on their warranty plus they did unnecessary work that they didn’t contact me about. I am done with them.
Is it a short? The sender (I think correct terminology?) or ?
This is 2001 Yukon XL SLT 2500 4WD 6.0
Sorry to be so long winded….
Any ideas will be appreciated.

 

[strutaeng]

I would look for a shop that has a scanner to check the transmission temperature and compare that to the cluster guage.

Or you'll need to buy a scanner that has that capability yourself. I bought the $80 TopDon dongle and I believe it shows that information.

The transmission temperature sender is part of the harness. You can replace the harness after draining the fluid and dropping the pan. They are like $70.

As to your question about the brake control: IDK. Why don't you simply unplug that and see what it does? Probably have to pull the wiring diagrams to see what other stuff is on that transmission temperature sender circuit. I "think" all that communicates through the CAN network, but can't remember off the top of my head.

 

[Moosemoon]

Thanks for the suggestions. Would a transmission shop do that? I have no place to do the work myself.
I do have a decent scanner but nothing registered in the past. Will hook it up again and see.
I don’t know that the trailer brake was a ‘plug in’ but I can take the controller and under dash cover off and look. Will try to do that tomorrow between snow and rainstorms.

 

[strutaeng]

Thanks for the suggestions. Would a transmission shop do that? I have no place to do the work myself.
I do have a decent scanner but nothing registered in the past. Will hook it up again and see.
I don’t know that the trailer brake was a ‘plug in’ but I can take the controller and under dash cover off and look. Will try to do that tomorrow between snow and rainstorms.

Yeah, a transmission shop should have a scanner that reads ATF fluid temperature. They probably charge you a small fee (hopefully not too busy to turn you away.)