My 2009 wrangler’s fan won’t start running unless I unplug the temp sensor. Also the temperature gauge will never go above halfway. I replaced the temperature sensor and it didn’t help. Abe advice??

 

Welcome to JKF.. The sensor works by measuring the temperature that's being given off by the thermostat and/or the coolant itself. The temperature is then sent to the on-board control system. ... As the control system receives the temperature from the CTS, it may trigger the cooling fan to either shut off or turn on. It is interesting that disconnecting the Temp Senor the fan works..
You can test the cooling fan temperature switch using a test light. Connect your test light to battery ground.

1. Start and idle the engine, and backprobe the connector terminals with the test light. ...
2. Wait for the engine to reach operating temperature.
3. Now backprobe the other wire at the connector. Please keep the JKF updated on your progress/success.