Weird problem: Fans aren't turning on, but relays still good

[gsx ftw]

So initially I thought one of my relays had gone bad, but then the other day when I had my HVAC heater/fan on (to keep my temps under 200...during the summer...it sucks) I noticed that both my fans will turn on.

I know there are three relays that have to do with the fans, and one for when the AC Condenser is on. My question is...is there a thermostat switch or something?

I talked to Sean at FFTEC, he said only the 1g's have this switch and 2g's don't.

If that's the issue, could it be a loose connection from the ECU, or the ECU itself?

This is all to my understanding. If any of you have any suggestions, feel free to chime in. Thanks.

 

[luv2rallye]

Check your 2 wire engine coolant temp sensor near thermostat. ECU uses it to turn on fans at different temps and speeds.

 

[gsx ftw]

What the problem is...is that the fans aren't turning on past 200 degrees, which they should be. I've been using the heater to keep my temperatures in check.

Noob question, but where is the thermostat? And about the 2 wire engine coolant temp sensor...how do I know its bad? Thanks.

 

[EagleTalonTim]

I am not exactly sure, but if i am not mistaken, there are 3 sensors for the coolant temperature. This may only be on the 1g, but there are 2 on the Tstat housing on the left of the motor and one on the bottom left of the radiator. The one on the radiator is what is supposed to turn on the fans. I have mine jumped with a wire so they stay on all the time.

 

[Staytuned]

2G's have a temp switch and temp probe in the thermostat housing to the left of the engine. The larger one with two wires is the one that controls the fans.

 

[luv2rallye]

Noob question, but where is the thermostat? And about the 2 wire engine coolant temp sensor...how do I know its bad? Thanks.

Where the upper radiator hose goes into the engine. Check it's resistance as engine warms up (unplug connector): Should be roughly 6k ohms @ 32F, 2.5k @ 68F, 1 @ 104F, 0.3 @ 176F.

 

[gsx ftw]

Thanks for the help, I'll bust out my DMM and check it out.

EagleTalonTim, I believe only 1G's have the setup you described.

 

[gsx ftw]

Let me get this right. I just took a look at the thermostat housing and there appears to be two sensors. The larger one toward the rear (not the one off to the right) is the one I should be testing, correct?

If it is faulty, do I have to (what appears to be) unscrew the sensor and replace it completely?