found possible reason for overheat...

[rgirard413]

i think i found the reason my car overheats and its because the main radiator fan doesn't turn on when its suppose to. If i take the relay under the hook out(the middle of the 5 fan ones(radiator and ac) i can put a test light in(grouning it out) and turn the fan on manually, however that spot on the relay shouldn't have power on it. Is it possible a sensor could be cause this behavior?

 

[ddavisaf]

http://www.dsmtuners.com/forums/showthread.php?t=200575

Yes, a non-operational fan will cause a vehicle to overheat.

 

[luv2rallye]

Is it possible a sensor could be cause this behavior?

Yes. That relay is controlled by the ECU (puts a ground on green/black wire on pin 1 with relay in place) but the ECU uses the coolant temp sensor to decide. This sensor is the 2 wire one (black, black/white) below the thermostat just rear of radiator cap.

 

[rgirard413]

i should be able to just test the resistance of that sensor to see if its still functional? If so, do you know what tolerance it should be in?

 

[chuckg]

This happend to me a while ago, and it ended up being a blown fuse under my dash. I'd check there first.

 

[rgirard413]

ive checked fuses like 10 times. they are all fine

 

[luv2rallye]

i should be able to just test the resistance of that sensor to see if its still functional? If so, do you know what tolerance it should be in?

Yes. The resistance should be 5.1-6.5 ohms @32F, 2.1-2.7 ohms @68F, 0.9-1.3 ohms @104F, and 0.26-0.36 ohms @176F. You can remove it (drain cooling system a little 1st to not spill out) and put it in water at those temps to test. Remember it's the 2 wire one (the 1 wire one is for dash temp gauge).