Need help diagnosing high CHTs - one radiator fan won’t run during active test (2015 GT ProCharged)

[SheepDog]

I tested all three fan relays and they are all good they all click and the 3 fuses are also good. I put the AC on max and that second fan doesn’t turn on.

You can be certain by applying power directly to the fan motor. The easy way to do this is with a power probe, but if you don't have one you can use a jumper wire from the Battery +. Just unplug the fan motor connector, apply ground to the ground wire, and power to the power wire.

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[horsepower addiction]

Once you know what circuit is the problem go ahead and jump the relay again and then test for power at the plug where it plugs into the fan and see if you’re getting power out. if you are then the fans got a problem if not then you definitely got a problem somewhere between the relay and the plug.

 

[Unas2k5]

You can be certain by applying power directly to the fan motor. The easy way to do this is with a power probe, but if you don't have one you can use a jumper wire from the Battery +. Just unplug the fan motor connector, apply ground to the ground wire, and power to the power wire.

Thanks. I do have a probe. I was going to unplug the non-responsive fan and turn my car on with AC on max then test for power at the connector. I’m about to go out and do that now

 

[Unas2k5]

I don’t think it’s going to be easy to use a probe because the connector is so damn low. I would probably have to remove the underbody and get to it from underneath the vehicle to test the fan. Would be nice if it was just the harness lol

 

[wingnutt]

I don’t think it’s going to be easy to use a probe because the connector is so damn low. I would probably have to remove the underbody and get to it from underneath the vehicle to test the fan. Would be nice if it was just the harness lol

cmon man, you know the saying…if it was easy, then everyone would do it

 

[horsepower addiction]

Thanks. I do have a probe. I was going to unplug the non-responsive fan and turn my car on with AC on max then test for power at the connector. I’m about to go out and do that now

This is not a valid test. If the ac isn’t working properly it will not turn the fan on so if you don’t have power at the plug you’re not gonna know if the problem is with the air-conditioning system or with the fan circuit

 

[SheepDog]

I don’t think it’s going to be easy to use a probe because the connector is so damn low. I would probably have to remove the underbody and get to it from underneath the vehicle to test the fan. Would be nice if it was just the harness lol

Like Nate mentioned above - you can jumper the terminals that the relay plugs into. This will test both the fan motor itself, as well as the wiring.

Applying power directly to the fan motor removes the circuit wiring from the equation.

If the fan kicks on when you jumper the relay terminals, then you know the fan motor and wiring are good. If the fan doesn't kick on, then you know that either the fan motor or wiring is bad.

If you apply power directly to the fan motor and it doesn't kick on, then 100% the fan is bad. The good thing about using a power probe as that you can poke through the wire and apply power without futzing around with the connector. The better way though, is to unplug the connector, and apply power and ground with the power probe. The shadetree approach is to do this with jumper wires and alligator clips from the battery

 

[wingnutt]

If you apply power directly to the fan motor and it doesn't kick on, then 100% the fan is bad. The good thing about using a power probe as that you can poke through the wire and apply power without futzing around with the connector.

lol, and what if he likes to futz…askin for a friend

 

[ORRadtech]

Like Nate mentioned above - you can jumper the terminals that the relay plugs into. This will test both the fan motor itself, as well as the wiring.

Applying power directly to the fan motor removes the circuit wiring from the equation.

If the fan kicks on when you jumper the relay terminals, then you know the fan motor and wiring are good. If the fan doesn't kick on, then you know that either the fan motor or wiring is bad.

If you apply power directly to the fan motor and it doesn't kick on, then 100% the fan is bad. The good thing about using a power probe as that you can poke through the wire and apply power without futzing around with the connector. The better way though, is to unplug the connector, and apply power and ground with the power probe. The shadetree approach is to do this with jumper wires and alligator clips from the battery

Depending on where you live poking holes in the wiring can lead to bad things.
Living somewhere in the rust belt with holes in wiring insulation just leads to corrosion and failed wiring. If you do take this approach it won't hurt to put a little liquid electrical tape on it.

 

[Unas2k5]

OK, does anyone know which of the fan relay is for the right fan or do all three fan relays just control both ?
Also to jump the relays do I need a spade terminal? ( don’t have )
Can I use my Milwaukee M12 battery to jump a relay ? Or can I try to jump it using the probe and the vehicles 12v battery ?

 

[Unas2k5]

These are the fuses and relays I tested and were fine. When I use my autel device to turn fans on high that means even the one on the right should be running ? Anyone know for sure ?

 

[Unas2k5]

This is not a valid test. If the ac isn’t working properly it will not turn the fan on so if you don’t have power at the plug you’re not gonna know if the problem is with the air-conditioning system or with the fan circuit

Gonna command the fan with an autel device to turn on high ?

 

[Unas2k5]

OK, you guys the connector is messed up. I unplugged it and plugged it back in. It wouldn’t work but to get it to work I have to pull the connector towards the vehicle towards the engine for it to make contact so I think that the harness is just messed up. Had to shorten video.

 

[G.T.]

Check this post, helped a lot when I was troubleshooting mine.

On a GT350 but GT is the same.

https://www.mustang6g.com/forums/th...nning-where-is-the-sensor.120923/post-2525657

 

[G.T.]

OK, you guys the connector is messed up. I unplugged it and plugged it back in. It wouldn’t work but to get it to work I have to pull the connector towards the vehicle towards the engine for it to make contact so I think that the harness is just messed up. Had to shorten video.

That looks to be it!

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