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the Coolant Temp Sensor is by the TB , i have a Autometer gauge on the Coolant Sender Wire for the gauges witch is on the thermostat housing wich is a 1 wire not 2...Take a meter and start your car and take the connector off and see if you get power to the clip before the fan, but becareful not to overheat because..i just did this myself because i thought my low speed wasnt working but i verified it by checking it with the meter, i guess i cant notice the difference when the low speed switches to high speed..i just recently ran a switch (temperarily untill i get dual fans with adj temp switch/custom radiator) to near the top of my hood by the wipers, i just kick it on before i drive around, useing the low speed power wire, fused it with a 30 amp fuse and connected it to the side fender relay on the drivers side, and grounded to my custom ground spot i have near there, now i noticed my temp is so much lower, my car used to idle and hit up to about 228-230ish and now at idle it only goes up to 210 tops..for not much work this is a good mod (could run it inside but mines only temperary) it helped me 20 degrees at idle and driving around usually doesnt go past 210 either..
what would be better is to make 2 switches inside your car, that run to each low and high speed so you could start the fan on low speed then switch to high speed so you wont burn out the fan motor, someone should make a cuircut of that without switches so you never have to worry about switching it on just hook it up to an acceossary so when your cars on it engauges the low speed fan the about 10 seconds later stop the low speed and engauge the high speed fan all the time ..that would be cool..cheap mod and nice performance...Alex LaChance..
From MN12Performance.com
Cooling fan motor will run at low speed:
If engine temperature is higher than normal. Cooling fan motor starts running at 106 *C (222 *F) and stops running at 101 *C (214 *F).
If A / C is on and vehicle speed does not provide enough natural airflow. Cooling fan motor starts running at speeds at or below 69 km/ h (43 mph) and stops running at 77 km/ h (48 mph).
Cooling fan motor will run at high speed:
If engine temperature is higher than desirable and cooling fan motor has been operating at a low speed.
At 109 *C (228 *F) and stops running at 105 *C (220 *F).