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On my 1993 Tempo, lately the temperature gauge has been completely erratic. Mostly showing cold but sometimes normal. It can change suddenly. There is plenty of coolant and the engine temperature is normal. I was going to replace the sender unit but I've noticed the fuel gauge may possibly be acting up also. The fuel gauge has always been somewhat erratic since I got the car in 1997, but lately I saw it showing less than full (a bit less than 7/8) very shortly after I had just filled it. I am thinking perhaps there is a gauge voltage regulator, and if so perhaps it's faulty? Also had the upper (only) climate control panel lights become first intermittent (would go off when any button was pressed but then come back on) and now are off constantly. The lower climate control panel lights are OK. I wouldn't think these are related unless there is a problem in a connector. Could anyone point me to what it might be? Is there a voltage regulator for the gauges?
 

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The float assembly in the fuel tank uses a mechanical potentiometer (variable resistor) to send resistance values to the gauge. - The inaccurate fuel reading could be due to a faulty sending unit or worn float mechanism.

The temperature sending unit also acts as a potentiometer but is solid state device (NTC thermistor). It sends a signal to the PCM for fuel injection and engine timing adjustments as well as signal to the temperature gauge. - From what you described it does sounds like you have bad sending unit.
 

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OK, thanks for the information. Some of the old cars had a mechanical voltage regulator that dropped the system voltage to the gauges but I guess that isn't done anymore and it's a good thing. The Ford dealer that always serviced it for me said the gauges were always a bit erratic on those. It's not that bad, just not as precise as some are. I'm not able to work on them anymore but I have someone who is going to look at it Saturday. I've had the car 19 years, never driven in snow so it's still solid, engine runs like new. No major problems in all that time. I've kept it and taken good care of it because it's such a gas saver.
 
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