Temperature sending unit

[RESTREC]

The temperature gauge shows cero all the time. I have changed the sensor, put a new instrument cluster provisionally, and put a wire directly from the sensor unit to the instrument cluster. Nothing works. Where can I find the wiring map for this ? Haynes doesn't show it. Only thing left to blame is the ignition swith, but if all the other gauges work well after I turn it on, I think that is not the problem Any suggestions ?
Thanks.

[RESTREC]

I examined the functionality of the temperature sensor thru the boiling water test introducing it in boiling water and measuring its resistance with an ohm meter. It was not good. I had pulled 2 used sensors and I checked the 2nd one and it showed it was ok. I put it back in the car and surprisingly it shows one line of temperature after the car has been driven in city traffic considerably. What happened before is that I hadn't warm up the engine enough. Please let me know 88 Aerostar owners, and probably other years, if in reality the needle only goes up one line when the motor is warm enough. If it does go up more maybe very old sensors loose sensibilty and I will probably have to buy a new one. So, do your temperature gauges go uo only one or two lines only ?

[RESTREC]

Originally Posted by RESTREC

I examined the functionality of the temperature sensor thru the boiling water test introducing it in boiling water and measuring its resistance with an ohm meter. It was not good. I had pulled 2 used sensors and I checked the 2nd one and it showed it was ok. I put it back in the car and surprisingly it shows one line of temperature after the car has been driven in city traffic considerably. What happened before is that I hadn't warm up the engine enough. Please let me know 88 Aerostar owners, and probably other years, if in reality the needle only goes up one line when the motor is warm enough. If it does go up more maybe very old sensors loose sensibilty and I will probably have to buy a new one. So, do your temperature gauges go uo only one or two lines only ?

Take a look at the thread "Heater Core reverse flush" The temperature sensor was perfect. The problem was a stuck open thermostat which meant a constant cool motor and no way for enough heat to build up for the needle to go up.