why did the temp gauge quit working?


Asked by May 04, 2013 at 12:35 PM about the 1999 Mercury Grand Marquis 4 Dr LS Sedan

Question type: Maintenance & Repair

the temp gauge didn't register upon initial start up.  After running it to operating temp the gauge doesn't register anything.  I've replaced the sensor in the manifold with negative results.  Where/what else can it be?  The vehicle has 216,000 miles if that matters.

9 Answers


The temperature sensor in the manifold provides the varying ground potential to the gauge. The gauge gets power from the instrument cluster. It either is not getting power or the gauge is bad. -- You can check the temperature sensor with a meter. See how many ohms to ground you read as the engine warms up.

6 people found this helpful.

Check your battery to make sure it's newer than seven years old. Clean the other end of the the negative cable as it's bolted onto the chassis/frame...this is important that it has solid ground at this point...also to the motor~

12 people found this helpful.

Yes as tenspeed you need to check the circuit with a meter. Your guage problably took a dump

3 people found this helpful.

I dunno why. parts go bad eventually. Since he said he replaced the sending unit its either a wire issue or the guage so checking the circuit with a meter will tell you which one it is.

3 people found this helpful.

Bcm has nothing to do with it.

2 people found this helpful.

the sensor is right in the middle of the engine~

5 people found this helpful.

he/she has replaced the sensor already so the diagram of where it is located doesn't seem necessary. your second diagram is incorrect the sensor is located on top in the intake crossover tube. as shown in the first correct but unneeded diagram.

3 people found this helpful.

...of course was there all along, the reason we aren't finding a bad fuse is because the chassis ground is weak...every start creates a slight "blue weld" from the 300 or so cold cranking amps...after a few hundred starts the corrosion between the two dis-similar metals creates a insulation zone of burned lug and frame....so grab a coarse wirebrush and wire brush the frame and lug...restoring ground to the chassis and to the fuel gauge~ final word....judge

2 people found this helpful.

my daughter has one of these cars. the check engine light came on a few months ago. the said it was the IAC valve so we replaced it. Now the light is back on and it says it is either the IAC valve or the temp censor what do you think? The gauge even after driving for 30 min barely registers. It has always read right in the middle.

8 people found this helpful.

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