I want to get my TEMP light to function again. Right now it turns on when I place the ignition in the ON position. While the car is running the light is out, but this engine only has a mechanical temperature sensor which works fine. I want to have BOTH so that the dummy light will turn on at 220-230 and I can consult my mechanical gauges at that time. What is necessary to get this working again? I can't seem to find such a part at kragen.com/autozone.com
Is there a single wire somewhere on the firewall that plugs into this sensor? How does it work exactly? Does it provide ground at 220-230 or something?

Nevermind, I found it in a search of the ENGINE forum. Search of the Heating and Cooling did not come up with a search earlier.

Napa has
Mileage Plus Electrical Temp Sender Switch - Light TS6471SB $ 7.99

Mileage Plus Electrical Temp Sender Switch - Light TS6607SB $ 5.99

I'm guessing they have to do with two different temperatures that they flick on at.

A temperature switch is just a contact that provides a ground to the engine block when it reaches its setpoint. Power to the switch is sent throught the TEMP light in the dash. There is a contact in the ignition switch that provides a ground to this circuit to test the light during cranking. This is what you want with an idiot light. I would assume they come in various settings. The one you listed (assuming it is a temperature switch) looks like it's setpoint is 195 degrees based on the part number.

A temperature sender is a variable resistor that provides a varying resistance to ground in relation to temperature that allows your temperature gauge to indicate the temperature of the engine coolant. The higher the temperature, the lower the resistance through the sender. These senders have to be matched to the resistance of the gauge they are connected to or the readings are meaningless.

[ 10-17-2003, 09:14 AM: Message edited by: Mark C ]