Temp gage reading wrong temp.

[Blackwater]

I have issues with my engine temperature gage. barely gets above 100 degrees. I have changed both sensors and instrument cluster. I hear the fan engaging occasionally but to no avail, gage doesn't change. It does move, so its not stuck. Any Ideas?

 

[east302]

Is the upper radiator hose getting hot? The thermostat should open at (depending on what you have) around 195-F.

If you have one, a scanner could read the output of the coolant temperature sensor which is what the computer uses. It is located by the thermostat.


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[Blackwater]

Is the upper radiator hose getting hot? The thermostat should open at (depending on what you have) around 195-F.

If you have one, a scanner could read the output of the coolant temperature sensor which is what the computer uses. It is located by the thermostat.


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Its a 1993 GMC. I changed the thermostat twice. Use too, it over heated a lot.

 

[Blackwater]

I think its the ECU.

 

[someotherguy]

I think its the ECU.

 

[east302]

Its a 1993 GMC. I changed the thermostat twice. Use too, it over heated a lot.

Scratch the part on the scanner then, I was thinking you had a vortec. When you say “use to”, do you mean the upper hose isn’t getting hot anymore?


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[Blackwater]

It gets warm, just not hot. little history on it. it was fine till I went over seas for 1.5 years. when I returned it started acting this way. Also takes forever to warm up to use the heater.

 

[superdave]

It gets warm, just not hot. little history on it. it was fine till I went over seas for 1.5 years. when I returned it started acting this way. Also takes forever to warm up to use the heater.

A cheap infrared thermometer gun is a great tool to see what temps you are actually dealing with. You'll know whether it's actually heating up or not. I can't see it not getting up to operating temp. The lack of warmth from the heater may be a clogged heater core. Have you flushed that?

 

[Blackwater]

yeah, I was thinking about going by harbor freight and getting one. I have an LQ4 build in my shop for this truck but it bugs me that the temp gage is doing this.

 

[90halfton]

What Dave said about the ir gun. Sounds like the gauge is working, and the thermostat isn't. Most likely failed open, if temp shows cold, and hose is cold. Would keep your heater from heating up as well.