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-   -   Check Gauges light and engine temperature help (http://www.wranglerforum.com/f19/check-gauges-light-and-engine-temperature-help-150939.html)

mindhunter 04-03-2012 08:59 AM

Check Gauges light and engine temperature help
 
I need some help with my 2002 TJ for all of you mechanics out there. No one has been able to figure this out.

After about 20 minutes of driving, and usually at a stop light or something, my temperature gauge needle will suddenly and quickly dip down into the red and the check gauges light will come on. About 30 seconds later, and whether still stopped or moving, the needle will move back to normal just as quickly as it dipped down. I don't think it's possible for the engine to actually be overheating and cooling down this quickly. Could it just be a sensor or something maybe? That seems to be the consensus.. but what sensor is it, where is it located, and how do I change it? :banghead:

Things I have already done to try and fix this based on the advice of others:

- Switched out thermostat with brand new one
- "Burped" coolant system
- Emptied and refilled radiator

Thanks in advance to anyone who takes the time to help me out!

zmotorsports 04-03-2012 12:01 PM

Sounds like it could be a bad coolant sensor. The sensor is merely a variable resistor that changes resistance with the temperature. There must be a bad spot in it which just happens to be where the temperature rises somewhat when the airflow across the radiator and engine decreases, such as when stopped at a stoplight. Once is sweeps back down past the open spot the resistance reads again and feeds the correct resistance to the gauge cluster.

The coolant sensor for the gauge is in the head near the rear in the 4.0 I6. I beleive the one for the electric aux. fan is the one in the thermostat housing but I could have them bass ackwards.

Mike.

mindhunter 04-03-2012 12:16 PM

Quote:

Originally Posted by zmotorsports (Post 2214580)
Sounds like it could be a bad coolant sensor. The sensor is merely a variable resistor that changes resistance with the temperature. There must be a bad spot in it which just happens to be where the temperature rises somewhat when the airflow across the radiator and engine decreases, such as when stopped at a stoplight. Once is sweeps back down past the open spot the resistance reads again and feeds the correct resistance to the gauge cluster.

The coolant sensor for the gauge is in the head near the rear in the 4.0 I6. I beleive the one for the electric aux. fan is the one in the thermostat housing but I could have them bass ackwards.

Mike.

Thank you. I will try that next

zmotorsports 04-03-2012 02:52 PM

No problem.

Mike.

Adijeep 08-07-2013 12:49 PM

Hi. I have the same problem
Was the cause the coolant sensor ?
Many thanks


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