Changed Temp Sending unit and Thermastat- No change - SOLVED

[Bigsarge1]

I have seen where folks have changed the TSU and/or the thermastat to fix cooling fan shutting off and no temp reading on guage and some were fixed and some were temporary fixed just to start doing the same thing a day or so later.
Here is my Dilemma- Yukon drained battery over night because fans didnt kick off. I check it out and decide to just change both a one time, the TSU and the thermastat. Also checked the wiring and plugs. Results- Never changed a thing. So I decide to unplug the fans and let it idle to see if it warms up even though the gauge stays at 160. after about 45 min of idling with the fan fuses pulled, the truck was hot. So now I know the new thermastat is opening but still no guage movement nor will the fans turn off. I have cleared the code and pulled the cables off the battery for extended period of time. Still no luck. I have a hard time believing that the only thing left is a bad ECM.

 

[Doubeleive]

I have seen where folks have changed the TSU and/or the thermastat to fix cooling fan shutting off and no temp reading on guage and some were fixed and some were temporary fixed just to start doing the same thing a day or so later.
Here is my Dilemma- Yukon drained battery over night because fans didnt kick off. I check it out and decide to just change both a one time, the TSU and the thermastat. Also checked the wiring and plugs. Results- Never changed a thing. So I decide to unplug the fans and let it idle to see if it warms up even though the gauge stays at 160. after about 45 min of idling with the fan fuses pulled, the truck was hot. So now I know the new thermastat is opening but still no guage movement nor will the fans turn off. I have cleared the code and pulled the cables off the battery for extended period of time. Still no luck. I have a hard time believing that the only thing left is a bad ECM.

I have seen this before and apparently there are some bad sensors and/or thermostats out there, some have had to change them multiple times.
45 minutes for the engine to heat up is a really long time, sounds like bad thermostat.

 

[Bigsarge1]

turned out to be a bad new part from Standard. The temp sensor.

 

[Joseph Garcia]

Thank you for posting the solution to your issue. Much appreciated.

Our collective knowledge base has been increased.

 

[OR VietVet]

That happens soooo many times from the aftermarket crap parts. We preach "use Genuine GM or AC Delco parts" when can.

 

[Joseph Garcia]

^^^^^x2^^^^^

 

[Doubeleive]

turned out to be a bad new part from Standard. The temp sensor.

standard sucks, do not recomend

 

[OR VietVet]

Back when I ran shops and carbs were still on the road, about 50% of the time, when we installed a Standard Products electric choke pull off on a carb, it was a crap shoot if it was going to work correctly.

 

[jets]

Last November there were a few days when the Yukons fan would keep running full speed and until a few minutes after shutting off the engine. No codes. Then it went away; last night it started happening again. Something about the colder weather... this year has been much milder than last year so it's as cold now as it was last Nov... I guess I should have the temp sensor checked. Anyone have the part number?