I recently noticed my pyrometer is acting really funny. It's reading about 200 degrees lower then usual. It's a banks gauge and thermocoupler. Is there a way to test them to determine what the problem is. I read some other forms that talk about reading the milliamps, but know of them tell you how to do it.

The meter and thermocoupler were put in a few weeks after the truck was purchased new in 1993. Do they go bad? I would guess they would be a go or no go. Everything seems to work its just about 200 degrees lower then it should be at driving speeds and drops below 300 as soon as your at a stop light. I live in Washington State so the air temp hasn't changed drastic to account for that much change in temp.

Thanks in advance

 

If it's like my Autometer, check your power and ground connections. Mine started acting wonky too when the ground wire came loose.

 

The thermocouple itself is a weld bead of 2 dissimilar metal wires. After a large number of temperature cycles, it could crack, and that would give you the symptoms.

I think usually under that condition the thermocouple resistance would go up significantly, which would give you a simple test. Worst reading would tend to be when cold.

Meter connections in a millivolt circuit is critical as cougar noted.

 

You may need to clean it, pull it and lightly emery cloth it. Might help and its easy to do.