My radiator rans do not turn on even at very high Temps. I replaced the ran sensor with a 180 degree temp sensor from Hawks and still nothing. I replaced both relay boxes and still nothing. The weird thing is when I use a multimeter and place the positive on the switch and the negative to a ground the fan turns on. Does anyone know what the issue could be? Maybe a bad ground? If so where should I be looking for the ground wire?

 

Are you referring to putting the vom to ohms and grounding the single wire cylinder head temp switch between cylinders 6 & 8 ?

 

Yes I recently replaced that fan temp switch. It is supposed to activate the fan at 180 degrees. It doesn't turn on at all. I'm stumped cause it turns on when I attach a multimeter to see if the sensor is getting voltage.

 

If your grounding the secondary fan temp switch wire though the vom the temp switch despite being new is defective if on is 180f. Does the primary fan kick on with aldl jumper ? Have you monitored coolant temperature via ecm readings to confirm command to relay for primary fan

 

I not familiar with how to conduct those tests. All I know is the primary fan does not turn on as I watch the temp gauge get into the. Well past the temp it should be getting to while in idle or park

 

Temp it should ? How are you measuring temperature, inferred gun ? Relying on old stock gauge is not a reliable method.The primary if stock ecm calibration chip will come on around 226f.

 

I would think regardless how the temp is measured at some point the fan should kick on and it never does

 

The gauge is not the most accurate way to measure cooling temperature.
you can temporarily install a mechanical temperature gauge to monitor.
or perhaps a fsm would be your best choice to diagnose.

 

I'm not familiar. What is a fsm?

 

factory service manual

 

youd be surprised how long it takes for some fans to kick on...especially if say dfor instance the thermostat is stuck open, its super cold out etc...

 

Update - Removed the Hawks fan switch. Cleaned it with a wire brush and reinstalled. I'm happy to report that not only was that the issue, the fan turns on at 180 degrees. It's such a huge improvement over the stock switch. Engine and plenum does not get nearly as hot as it did before. I can drive for a long period of time and still touch the plenum without scorching my hand. I know a lot of people on this forum talk **** about Hawks but I'm impressed with the fan switch.