I purchased a new coolant temperature gauge sender unit and I have tried all wire combinations. I can't get the gauge to read accurately, the gauge moves and will only read when the car is not running. When running it stays at zero. Any advice??????

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Fiero84

Are you changing the correct sensor? There are three on the '84.

http://www.fierostore.com/Tech/Default.aspx?Id=189

I changed the sensor that is vertical in the block. I made sure i wasn't changing the fan switch or dcm temp sender.

Is your alternator charging? When the engine is off, you are using battery voltage, but when the engine is on, you should be getting power from the alternator.

[This message has been edited by Gall757 (edited 02-04-2015).]

yes the alternator is charging, it is just the gauge malfunctioning. all the other gauges are working (Ex: charging gauge). I was considering a bad gauge.

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Fiero84

You didn't use Teflon tape did you? I can't remember if this sensor is grounded to the engine, but that would also cause some issues.

It is grounded to the engine. One wire is for the gauge, the other is for the idiot light. The gauge should sit on the 100 mark if the engine is cold and the ignition is turned on without starting the engine. If it's not at 100, then the needle has slipped and needs to be repositioned.

You can test the gauge and light by unplugging the connection at the sender. Insert a paper clip into one terminal and then the other. Test the light and gauge by turning the ignition on and briefly grounding the paper clip to the base of the sending unit. The light should come on with one terminal, and the gauge should peg with the other terminal. Don't hold the ground very long when testing the gauge terminal.