2004 Denali coolant gauge shows hot

[Stacker721]

My 2004 denali xl has a strange temperature gauge issue. First of all, it runs great, has 139k, I've owned it since 2009. I changed the water pump, thermostat and all coolant hoses at 103k when the water pump started leaking.
What happens is the coolant gauge will show normal temp, just left of straight up, once the truck is warmed up. Upon restarting, once warmed up, the gauge indicates anywhere from 240 to 260 degrees. Everything under the hood seems normal..coolant is topped off, no leaks, no lights on dash. If i disconnect the battery once stopped, the gauge resets and doesn't present the problem until multiple start/shutoff cycles. It will run at normal temp the first time after resetting the battery, then it happens again.. I'm thinking the coolant temperature sensor, i have no scanner, so i don't know about codes..any ideas?

 

[Z28TWITCH]

The sensor is cheap and its been a year or two since new coolant was added. Could also just be the cluster itself. First I would be absolutely sure your not cooking that engine. Second, I would pull the sensor and swap it for a new one. If you still have the problem I would surely suspect the cluster/stepper motor.

 

[oldchev]

I concur its either the sensor or stepper motor (somewhat common). Use an infrared thermo checker ($24.99 at HF) to verify your temps at thermostat housing and radiator coolant hoses. That will satisfy the actual temp.
Believe it or not a 6 pack stepper motor set for the whole gauge cluster is under $20 on Amazon. I have not done this but seems straight forward.

 

[Doubeleive]

I would suspect the sensor, cheap and easy to change to rule it out

 

[Stacker721]

Got the sensor in the mail from Amazon tonite, will find out soon.Thanks for all the help.

 

[Stacker721]

Got the sensor in the mail from Amazon tonite, will find out soon.Thanks for all the help.

ok just changed the sensor...no change. truck was totally cold, disconnected the battery which resets the gauge to far left. Drove vehicle to full operating temperature and it was fine..stayed at 190 degrees, until i shut it off and restarted. Gauge immediately jumped to 240, shut off again, did not return to zero or far left. restarted motor, gauge went off the far right side passed the numbers. What is this stepper motor you guys are talking about? Is there a thread on this, I've never heard of it...

 

[Fless]

Have you read the temp using a scan tool through OBD?

Others can explain it better than I but each gauge has a stepper motor that controls the gauge needle. Very common problem to have them wack out on the NBS gauge cluster.

 

[Rocket Man]

ok just changed the sensor...no change. truck was totally cold, disconnected the battery which resets the gauge to far left. Drove vehicle to full operating temperature and it was fine..stayed at 190 degrees, until i shut it off and restarted. Gauge immediately jumped to 240, shut off again, did not return to zero or far left. restarted motor, gauge went off the far right side passed the numbers. What is this stepper motor you guys are talking about? Is there a thread on this, I've never heard of it...

Just google it. There’s Youtube videos on it.

 

[Stacker721]

cool..

 

[Z28TWITCH]

Stepper motors on that truck are a little involved, but pretty easy once you figure it out. Decent soldering skills are required. Like others have said, there are TONS of youtube videos out there to help you though it. You could replace all of them yourself for cheaper than a 12 pack of good beer. I can walk you through it if youtube isnt your thing.