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temperature gauge problem

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acman60

Guest
This is the problem my temperature gauge.I turn on the car and the gauge go to 250 and the car is not hot.The car runs in the red.I changed the temperature sensor.I think it may be the gauge, is there a way to check the gauge out.its a 1979 L48 THANKS MARK
 

Hib Halverson

Technical Writer for Internet & Print Media
Joined
Jan 10, 2001
Messages
13,453
Location
CenCoast CA
Corvette
71 04 12 19
Connect a known good gauge to the sensor and compare the readings. if the gauge in the car differs by much, obviously, you need to replace it.

Another, but slightly less accurate test, is to get a "temp gun", such as a Ratek Autopro, and read the sensor body then compare that temperature to what the gauge reads.
 

Mr. Chuck

Well-known member
Joined
Jan 19, 2005
Messages
230
Location
Southern California
Corvette
1981 Two tone silver / dr grey
Temperature Gauge TroubleShooting

Connect a known good gauge to the sensor and compare the readings. if the gauge in the car differs by much, obviously, you need to replace it.

Another, but slightly less accurate test, is to get a "temp gun", such as a Ratek Autopro, and read the sensor body then compare that temperature to what the gauge reads.

Here is a basic DC indicator circuit trouble shooting method you can try before getting behind the console; this is one I used many times during my years as a Naval Aircraft Electrican Mate repairing DC instrument circuits.
Basic DC temperature indicating circuits checks are: 1. With temperature sensor disconnected at the sensor, with key turned on, the gauge should read zero / to far left of gauge. 2. Using a test lead (needle on one end & clip on the other end) connect the disconnected sensor connector contact to the car frame or on the eng block, gage should read maximum / needle to far right of gauge scale, if not look for open ( burnt, broken, spread contacts in sensor connector) in the wiring from sensor to gauge. 3. Sensor check; Using Ohm meter (zero meter first), select lowest ohm scale on meter and then read from sensor electrical contact to Eng block or a good, non-painted metal frame point, the meter should read some value greater than zero (max deflection to the right), reading will vary with ambient temperature at the time.
Hint: The sensor circuit path is from the electrical contact through the sensor element & to the body threads to the engine block, use of teflon tape may interfer with this path and may cause an open circuit / maximum reading on the temp gauge. 4. If the temp gauge doesn't give these reading then I would suspect the gauge as being bad and/or loose or damaged contact at the rear of the console.
Hint: A TS good process is to always write down the results of each test, so as to not get confused, especially if you don't get done in one sitting or if interruptions come along.

I hope this isn't too technical, I have assumed you have some experience with using an Ohm meter and wiring trouble shooting. I have attached a copy of the gauge Warning Light circuit from my shop manual.

Good luck, feel free to ask any questions related to reading or conditions you find.

:upthumbs
 

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