[tkoepp]

OK, I have read through the various threads and tried to test all that I could. My fan is not coming on when it should, here is what I have tried..

Checked the cooling level, all good

Removed the powdercoat / sanded the ground and reseated it.
Jumpered the fan ground to a known good ground,
Pulled the wiring harness on the switch and jumpered from the bottom of the switch to a good ground... none of the above worked..

I then placed my test wire IN the wiring harness that connects to the switch, then the other end to a good ground and the fan turned on.

So I think that it is a ground issue, but not sure. Could it be a grounding issue further up on the harness? I read that it connects somewhere under the tank?
Thank you in advance for your help

 

[mooneydriver]

Tim, when the fan switch senses temperature increase (approximately 208 degrees F), the switch closes completing the circuit to ground activating the fan. I understood you to say that you connected a jumper to the terminal on the fan switch and other end of jumper to ground? That should make the fan run. This temperature switch contacts are normally open and contacts closes when water get hot. Hoping your problems are minor.

 

[tkoepp]

I understood you to say that you connected a jumper to the terminal on the fan switch and other end of jumper to ground?

Correct
So is that a bad switch then? or still possibly a grounding issue?

 

[mooneydriver]

I would heat the switch up in a oil bath to 207-216 degrees F. measured with thermometer to see if the switch if working properly. The only way to get the switch to close it's contacts is by heating it. I doubt that the switch isn't grounded as it's threads ground to the raditor when installed. I wouldn't rule it "not grounded" completely out as someone might have insulated the threads with teflon tape or other sealant. I recommend OIL bath in lieu of WATER due to boiling point of water is only 212 degrees and switch might require a few degrees higher. You might want to pull switch and clean threads and reinstall prior to heat testing, your call. Wishing you well.

You know that all the circuit is good except through the switch as the fan activates when you jump from the terminal of temp sw. to ground.

 

[dirtdobber]

Removed the powder coat / sanded the ground and reseated it.
Jumped the fan ground to a known good ground,
Pulled the wiring harness on the switch and jumped from the bottom of the switch to a good ground... none of the above worked..

What did you use as a known good ground?

I then placed my test wire IN the wiring harness that connects to the switch, then the other end to a good ground and the fan turned on.

If I read this right, you by passed the SWITCH ASSY., THERMO which will only tell you if the fan is working nothing more.
Since it is a 05 it is very possible that the SWITCH ASSY., THERMO is bad.
You can either test the SWITCH ASSY., THERMO or replace it for good measure. Regardless of mileage the switch can go out. If I were to replace the switch I would do a complete maintenance on the cooling system. Replace the coolant -flush the system, check the water pump, replace the thermostat, and the coolant sensor.
It is time consuming but not hard.

 

[tkoepp]

Thanks for the advice guys, this place is the best, and it is that way because of people like you.

 

[coker737]

I would R&R the switch before I go shaking wires. Most posible cause.

Here in Texas my fan is running it's lil blades off.

Switch Can't cost THAT MUCH. yea right. Good Luck

 

[dirtdobber]

Around $38 + shipping or $51 from dealer plus tax

Is the light coming on?

If the light is not coming on there may not be a problem. The only time ours come on is when stuck in traffic. You could also have build up on the sensor if you have not changed the coolant since 05.
It is recommend to change the coolant ever 2 years.

just a thought

dd

 

[tkoepp]

No the light is not coming on..

Good point, I will do that...

Around $38 + shipping or $51 from dealer plus tax

Is the light coming on?

If the light is not coming on there may not be a problem. The only time ours come on is when stuck in traffic. You could also have build up on the sensor if you have not changed the coolant since 05.
It is recommend to change the coolant ever 2 years.

just a thought

dd