Stuck temperature gauge

[MGG]

I looked at several other threads but didn't find one that would relate.

My temp gauge in my 02 Explorer (4.0) is stuck. It stays in the middle all the time. Even when first start in the morning when it should be cold. Does this mean my thermostat is stuck either open or closed?

 

[n2epv]

I would guess that you have an electrical problem or the gauge is physically stuck. You are correct, with the engine cold in the morning, the temp gauge should be at the bottom and not in the middle. Here's a link to the 3rd gen instrument cluster test -

http://www.explorerforum.com/forums/showthread.php?t=186860&highlight=guage+test

Running this test will sweep all the gauges in the cluster from their lowest to highest positions.

 

[vipersinu2]

unplug the sensor from the thermostat housing and see if the gauge goes down, i would get the fixed because the trucks computer adjusts fuel air mixture off the guage cluster

 

[MGG]

Ok gentlemen, I tried both these suggestions. The gauge sweep was cool but the temp gauge didn't budge. Also I unplugged the sensor from the housing and it still stayed stuck.

The gauge does go down with the ignition off but as soon as the gauge gets power is when it shoots right to the middle.

Could the sensor be bad? or something in the gauge cluster?

How hard is it to take the cluster out, and what to look for?

During normal driving conditions what temp should the coolant be at?

 

[MGG]

I ended up buying an ultra gauge to monitor my coolant temperature. As it should it starts out cold and warms up to around 185 and bounces around a few so degrees as I drive. So the thermostat is working properly. Seems like I just have a bunk gauge. It is still reading right in the middle as soon as it gets power. Still can't figure out why its doing that but I guess I will just monitor the temp from the ultra gauge for now.

 

[vipersinu2]

some models have 2 sensors for the thermostat, 1 for the computer and 1 for the temp guage, look at the thermostate housing if there are two plugs disco both and see what happens