Bad coolant temp sensor or ground? Help asap
Staging Lane
Joined: Jan 2018
Posts: 77
Likes: 0
From: Inland Empire, CA
Okay guys I replaced the coolant temp sensor and the pig tail but still getting a check gauges light and the water temp was pegged. How Can I test if the sensor is getting a good connection? Is it just a bad sensor?
Launching!
Joined: Nov 2015
Posts: 206
Likes: 13
The 1998 temp sensor has two different thermistors that control the dash gage and the PCM using separate circuits. The dark green wire goes to the gage and the ground path is through the thermistor from the sensor base being screwed into the head. If you grounded the dark green wire, in effect you would be by-passing the sensor and the gage would read hot all the time. If the yellow wire going to the PCM is grounded, it would essentially be the same situation, only the PCM functions would be affected. You need to trace out the circuits to make sure no wire has grounded out.
Last edited by peterpar; Mar 23, 2018 at 12:32 AM.
Staging Lane
Joined: Jan 2018
Posts: 77
Likes: 0
From: Inland Empire, CA
I’ve rewired the pigtail and soldered my wires. The gauge reads fun now but once the car reaches 210 degrees and the fans kick on the idle shoots up to 2k then drops to 800. SES light still says it’s the coolant temp sensor. Any guesses?
Last edited by Dylanlars; Apr 9, 2018 at 07:32 PM.
Registered User
Joined: May 2018
Posts: 2
Likes: 0
Did you ever figure this out? dealing with a similar situation with my 98 z28. replaced sensor, acted fine for a day then the gauge started pegging making it unable to start with a warm engine unless gas pedal was mashed to the ground, killing the injectors. Does your car have a hard time starting with a warm engine when your gauge starts acting up?
Staging Lane
Joined: Jan 2018
Posts: 77
Likes: 0
From: Inland Empire, CA
Did you ever figure this out? dealing with a similar situation with my 98 z28. replaced sensor, acted fine for a day then the gauge started pegging making it unable to start with a warm engine unless gas pedal was mashed to the ground, killing the injectors. Does your car have a hard time starting with a warm engine when your gauge starts acting up?
Teching In
Joined: Apr 2017
Posts: 5
Likes: 0
I have a 2001 3.8 bird and after about 6o miles or so, my gauge would drop to zero and the cooling fan come on for no reason. If I reset the codes, everything is fine. No idle/rpm surge at all. Suggestions on this?
