I have recently swapped over to a 4core radiator( Original sprung a leak ) with a dual electric fan setup.
I drilled and taped the water pump right behind the idler/tensioner pulley. And put the sensor in there. The radiator came with a cooling sensor (cheap Chinese no name sensor) that would ground its self when the temp hit 185. After everything was setup and ran for the first time, it worked. Temp came up, fan came on.
Then the issues started. After that it wouldn't turn the fans on. I know the fans work (if I ground the wire to the sensor fans come on).
I thought maybe, I had a air in the system and water wasn't getting to the sensor. So I added more water, ran out with it the cap trying to burp the air out. Eventually the solenoid started buzzing. I bought a new temp sensor (ACDelco Professional D1858D Engine Coolant Temperature Sensor)
and new solenoid. This was the wrong type sensor.
After install, and burping the system, new solenoid buzzes, and fans still do not come on. But if I ground the wire to the sensor, fans work.
I'm not sure of the issue.
Any ideas?