1993 Chevy Silverado 350 engine temp gauge reads low

bgbg01
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Joined: Sat Feb 28, 2015 11:05 am

1993 Chevy Silverado 350 engine temp gauge reads low

Unread post by bgbg01 » Sat Feb 28, 2015 11:24 am

My mechanic checked the actual temperature when the engine was at regular operating temperature with his computer and it indicated the actual temp was 185 degrees while the gauge indicates 110 degrees. I grounded out the temp gauge to verify that the gauge itself was okay and it checks out fine. I replaced both sensors, one near the thermostat and the other next to #1 cylinder and the problem still exists. The Chevy service manual says that once the sensors have been replaced and the problem still exists, there may be resistance in the circuit due to corrosion or a loose connection. It then says to "Clean and tighten the terminals and connections in the circuit and check for resistance in the ground path of the sensor." How do I locate these terminals and connections and check the resistance?

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carriedi
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Re: 1993 Chevy Silverado 350 engine temp gauge reads low

Unread post by carriedi » Sat Feb 28, 2015 11:48 am

you would be looking at the dark green wire that goes from the temperature sender to the instrument cluster. Using an ohm meter, measure the resistance between the sender connector contact and the instrument cluster connector. (You would have to remove the cluster and unplug it) The cluster connector should be A to Z on the connector with the dark green wire being #R. However, most of the time, if the correct coolant sender is put in and the gauge is still reading cold, it's a bad gauge unit.
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bgbg01
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Joined: Sat Feb 28, 2015 11:05 am

Re: 1993 Chevy Silverado 350 engine temp gauge reads low

Unread post by bgbg01 » Sat Feb 28, 2015 3:13 pm

Thanks for the reply. The gauge tested GOOD! I'm presume the instrument cluster connector is located somewhere under the dash and not sure what resistance amount I would be looking for if I were able to complete the resistance check, and if the resistance was not correct, that would lead me back to corrosion or loose connection in the circuit somewhere since the gauge and sensors are good!

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carriedi
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Re: 1993 Chevy Silverado 350 engine temp gauge reads low

Unread post by carriedi » Mon Mar 02, 2015 11:01 pm

to test a gauge to see if it's accurate, you need a known resistance that will show a set reading on the gauge. Grounding the sensor wire will only tell you is direct ground will peg the needle. It won't tell you if your gauge is telling you the accurate temperature based on the resistance of the temp. sender.

If you can find another truck similar to yours and their gauge reads normal, you could run a jumper between the two ground cables and then run a jumper from your temp connector to their sender and see what your gauge reads. it should read the same as the other truck. Ohm your jumpers. they should be zero to give you a good reading
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JerryLtowIt

Re: 1993 Chevy Silverado 350 engine temp gauge reads low

Unread post by JerryLtowIt » Thu Feb 22, 2018 4:28 am

Had the same issue recently on my 93 Silverado. After replacing both sensors, pulling the gauge assembly out testing resistanceses, it turned out to be a faulty thermostat.

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