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 Temp Gauge/Sensor Testing

 Created by: 65AMCS
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 Posted: Nov 3, 2019 07:11AM
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Hello.

Well I did the test as instructed, on the temperature gauge and would you believe it; it worked and the gauge went up to H (Hot)!  I just love it when a helpful post actually is helpful with MY autos.  Looks like I will install a new sending unit.
Thank you very much.

 Posted: Oct 28, 2019 05:25AM
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Hello.
Thank you.  Good info to have.
The voltage stabilizer also connects to the fuel gauge.  My fuel gauge works fine so I am going to assume the voltage stabilizer is OK.  The car is at a remote location. 
I will try the gauge test; disconnect the green/blue wire from the sending unit and hold the metallic terminal on the wire against an earthing point on the engine while the key is in the run position.  The gauge should go to/over the hot point on the gauge.  And the rest of the story: If gauge doesn't move, gauge is broken.  Gauge moves to "H" sending unit broken.  As I stated; the gauge needle moves a little when the key is turned on so I am thinking it is the sending unit. 
Thank you
Tim

 Posted: Oct 26, 2019 08:24PM
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US
The gauge and voltage stabilizer test is to disconnect the green/blue wire from the sending unit and hold the metallic terminal on the wire against an earthing point on the engine while the key is in the run position.  The gauge should go to/over the hot point on the gauge.

I don't know the resistance curve of the sender.  If you can fake a gauge setup in your kitchen you can at least check 2 points.  Place a thermometer in a pan of water.  Wire up the system on your counter.  Heat the water to boiling.  Lower the wired sending unit into the pot.  Keep it below the surface of the water but do not let it touch the pot.  With the water boiling the gauge should indicate just below the "H" region of the gauge scale.  Turn the heat off and allow the water to cool.  The gauge should indicate "N" when the water temperature is about 185 oF.

If you are uncertain how to wire up the gauge and sender to make these tests in the kitchen post back and I'll elaborate.  For sanity it is easier to do in the garage with a hot plate and pan of water.

Doug L.
 Posted: Oct 26, 2019 06:34PM
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Hello.
I have a 1965 Austin Cooper S.  The temp gauge isn't working.  It was working months ago but not today.  I have looked for a test procedure, found none.  I have checked and verified the wiring, all good.  Turn the key and the needle moves slightly towards center of the gauge so I am thinking the gauge itself is OK, maybe?  I don't know how to test the gauge or sensor.  Sure, put sensor in hot water but need...what resistance reading or something.  Hope someone can steer me to testing procedures.  I could buy a new sensor (PN?) for "S" car, but could be good $ after bad $.
Thanks much for any help.
Tim