GMC PickUp Question re thermostat

[heather]

We have a 1992 GMC Pick up

Today when it got turned over the "Check Gages" light came on & stayed on

The thermostat went way over to the right and stayed there

Checked under the hood - doesn't look like it's overheating - doesn't act like it's overheating

Heat is coming from the vents, so water is circulating

Any ideas?
Is the thermostat blown maybe?

THANKS!

PS - I can provide more info. if needed

[jeffinmalvern]

Which motor do you have?
Does it sound normal when running?

[arabian knight]

If it was the Thermostat it would be over heating. I would check to see if the Wire is connected to the Temp sensor first make sure it has a good connection there and if it is it probably is the Temp Sensor that went bad, and not the thermostat.,

[Yeti]

well sending units do go bad. the biggest thing here is make sure its not a real problem. if its making heat and not acting weird its most likely just the temp sender. theres one screwed into the intake right next to the Thermostat housing. it should have a plug with two wires. its the one that goes to the computor and controls the fuel control and tells your computor how hot or cold the engine is. so if you do anything make sure its working.
things to check first before replacing stuff...
1. is the Radiator full of fluid? if the sensor is not submerged then it will read something other then the truth.
2. is the fluid in the radiator 50/50 water & antifreeze mixed? test to make sure its good for about -30*. if its pure anti freeze it won't absorbe heat and can cause damage. if so drain some out and thin with water.

3. if the radiator wasn't full and needs fluid where did the fluid go?
if the fluid is missing check for leaks around the water pump by looking up at it from under the truck. you can't see the leaks under the pully from on top.
4. if theres leaks found what to do? come back here and we'll discuse what you have found.

[tinknal]

Does the temp redline the instant you turn the ignition on? (with a cold engine)

Is so it is for sure a sensor problem.

[heather]

Originally Posted by tinknal

Does the temp redline the instant you turn the ignition on? (with a cold engine)

yes

THANKS for all the info. people -
We will be checking some things out & if I have more questions, I'll get back with you!!
THANKS!!