Engine Coolant Temp Sensor, Or ?

[TravisAZ]

2003 Silverado SS

 

The following problem pops up occasionally - it is not very consistent.

 

After driving at 70mph on a freeway in 100* weather, the temp gauge reads 160*, and the engine idles around 1k rpm. Shut the truck off for a few mins, re-start, temp goes to normal and the truck runs fine. After this, the temp guage may eventually fall off again, or the truck may run fine all day.

 

So it seems like the computer is getting a bad temp reading.

 

does this sound like a coolant temp sensor? If so, where is it and how should I test it? I am assuming that the sensor would give data to the PCM and the guage, so it probably isn't a guage problem since the truck runs bad as well?

 

I guess it could also be a big air bubble in the coolant system?

 

Thoughts?

[TravisAZ]

Ive figured out that when the truck is placed back in park, the engine temp gauge functions as normal.

 

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[txab]

Does the engine run differently then too?

[TravisAZ]

Does the engine run differently then too?

 

Yes Sir - When the truck is in Drive, the gauge never moves, and the truck idles around 1k rpm when sitting with foot on brake. Feels like the truck is pulling against the brakes.

 

When the Truck is in Park, the gauge works, and the truck runs like normal.

[TravisAZ]

Does the engine run differently then too?

 

Yes Sir - When the truck is in Drive, the gauge never moves, and the truck idles around 1k rpm when sitting with foot on brake. Feels like the truck is pulling against the brakes.

 

When the Truck is in Park, the gauge works, and the truck runs like normal.

 

 

For some reason, I thought there was a sensor that fed the computer and a sending unit that fed the gauge. Apparently this isn't correct - I replaced the sensor, and it fixed it.