hello, the temperature gauge on my 1990 f150 has been acting up. even if i drive for 20 minutes the gauge barely goes up and im not sure why. is it the sending unit for the gauge, or the gauge itself? is there a way that i can test to see what is the problem?

 

Thermostat may be stuck open.

 

These dash gauges read low anyway but there are only a few things that could be causing your issue. As mentioned if the thermostat is stuck open the motor will take a long time to heat up, a simple test for that is just switched on the heater.. if you get lots of heat the thermostat is probably OK.
The sender could also be bad or the connection to it corroded. It works by grounding the gauge, so test that by removing the wire and grounding it on the engine.. the gauge should peg. The sender location depends upon your engine, it's not the device on the thermostat housing it's a little single wire thing about the size of a dime either in front of the #5 injector in the lower intake on the V8s or down on the side of the block under the upper intake for the I6.

 

hey thanks for telling me where it is i couldnt find anything online for it. big thanks my man. how ugly can the send be to replace? and is it the same one for any of the v8 engines? are they interchangable?