Temp gauge in 90 GT very...

A new sender from the parts store would have been 4 bucks.

Anyhow, get a real gauge. The stock gauges were not calibrated or accurate enough to be of any use.

Good luck.

The simple fact is that the stock gauges are not much more like warning lights. They have tremedous hysteresis built into them because if a gauge actually moves accurately, new owners run to the dealership every week because the needle changed positions.

FWIW, the stock temp gauge in my '88 reads 35* too cool at 190*F. Not what I would call accurate or useful.

If you dont want to add gauges openly in the cockpit, you could install one someplace discrete (glovebox, etc) or what I have done is put electronics on plates under the dash. The plates have cabinet hinges that allow the plate and device to fold up and out of sight but I can also fold it down and see what's going on. Since none of this is permanent, unless you enter concours car shows, it would work.

Another option is a rad cap with a gauge in it. This is easily swappable before shows and would allow you to try and calibrate the stock gauge. Or install a gauge under the hood.

Just some random ideas. I personally don't feel comfortable without decent instrumentation. Then again, it's over 100* today in the desert so this stuff is more important to me than folks in cooler locations.

Oh, the point about the sender was to get a new one. I dont especially trust senders and sensors that have been sitting and rusting in J/Y's, Motorcraft or not.


Good luck.

Disconnect the temp sender and put a 10Ω resistor between the wire and ground. Turn the car to the 'on' position. You should see the gauge rise smoothly all the way up.

It will test the sweep and input of the gauge by simulating the sending unit's upper end. Small resistor will work. I've used 1/4W with no problem. You will know if the gauge is capable of giving a high reading. If the gauge doesn't sweep high then you know you have a wiring or gauge problem.

To test for a low reading you would use a 74Ω resistor.

Also, check the ground strap that goes on the back of the drivers side head to the firewall. Then check the number 8 pin on the white 10 pin connector on the back of the intake. You might as well clean the all the pins and bend the female pins on the connector with a nail or something for better contact. (If you do the black side the car might idle better.)

I suppose you have a thermostat in the engine, I know it sounds stupid.

I tried everything in this thread and more and my temp gauge still acts funny with the headlights on, anyway I ended up getting a real temp gauge.