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Temperature sensor fault

Tiny
MARTINCOBALT
  • MEMBER
  • 2010 CHEVROLET COBALT
  • 2.2L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 120,000 MILES
After changing the radiator fan and the thermostat the car stop reading the coolant temperature. So I changed the temperature sensor, but after 3 day stop reading again, so I changed it again. I summary I chain the temperature sensor three times, but still having the same problem after few days stop reading again and the A/C stop working because the temperature sensor. Finally I found that when I disconnect the battery for few hours and connected again then the sensor start working again. So know I'm don't know what is the real problem. Also I chain the temperature sensor connector, but still with the same problem. Could be the entire wiring or the computer? Please help.
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Tuesday, September 10th, 2019 AT 7:05 AM

3 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
Welcome to 2CarPros.

What I need you to do is check for ground and voltage at the plug to the sensor when the sensor fails. I attached a picture of the plug and circled the two wires and what they are for. The one listed as a "low reference" is the ground, so you will have to check for continuity to ground on that wire.

If we find the signal to the plug to be the issue, then we have to suspect it is a computer related issue or a wiring issue. Often times, the pins on the control module can corrode and break, only making connections at times. Also, the wire it self may be damaged at a certain location and shorting.

The best thing to do is to actually have a scanner that can read more than power-train codes and scan for related codes. If you have a scanner, check to see if there are any diagnostic trouble codes.

Here are a few links you may find helpful:

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

https://www.2carpros.com/articles/how-to-use-a-voltmeter

https://www.2carpros.com/articles/how-to-check-wiring

Let me know what you find. At least we can eliminate an issue with the sensor itself.

Take care,
Joe
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Tuesday, September 10th, 2019 AT 6:45 PM
Tiny
MARTINCOBALT
  • MEMBER
  • 4 POSTS
Hi Joe,
Thanks for your fast response and your help. I check the cable connector for continuity and the voltage on the connector is 4.8 volt. And has good continuity; so I disconnect the battery and then disconnect the plug that go to the computer and clean it with an electrical cleaner and put it back to the computer and reconnect the battery. So far didn't fail again; I think I have to wait until the sensor fail again and then star with the test of the continuity and the voltage test again to see if the problem is with the cable or the computer. Thanks for all your expert advice; definitely if I have the same problem I will ask for your advice.
Thanks,
Martin
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Friday, September 13th, 2019 AT 8:20 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
Welcome back:

You are very welcome. Let's keep our fingers crossed that it doesn't happen again. Maybe it was simply a dirty connection, which is possible.

Take care and let me know if you need anything in the future.

Joe
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Friday, September 13th, 2019 AT 5:43 PM

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