3 wires need identifying

[hot_roder09]

3 wires under the hood of my truck have power when the key is on one of them is red and is hot all the time when the key is on (and my motor will not run unless this wire is attached to my coil) , one is red and white striped and is powered all the time when the key is on but when you attach it to the coil it losses some of it's power (my test light fades out but my light comes back once you diconnect this wire from the coil like it is back to full power) , and the other wire is white and has power to it but it comes and goes (makes my test light blink like a turn signal but the turn signal is not on) ,all the time the key is on and none of these have power when the key is off. i tested these wires with a test light .

[BobbyFord]

The red is coil positive. the red with white is the temp sender, the white with red is the oil sender.

[hot_roder09]

why is the white with red wire making my test light flash on and off

[BobbyFord]

The oil sending unit is an electro-mechanical device and gets a pulsed signal. The temp sender is different and is not electro-mechanical, instead is a temperature dependent resistor (thermistor) that does not get a pulsed voltage signal.

[hot_roder09]

thanks for that info,but what i am wondering is can i use the coil positive wire for my electric fan so that it will run with the key on only , and if i do this will this effect my coil or my fans performance

[BobbyFord]

The coil wire is a resistance wire and does not provide 12 volts.
Coming off of the back of the ignition switch there is a single wire that has a 3 hole female pigtail. You can use that for key on power up, but I would only use it to switch the relay for the fan.

[hot_roder09]

ok than what about if i hook up to the back of the alternator on the s post will that provide 12 volts of power for my fans, and provide key on and off power

[fordman]

if you run it straight off of the alt battery power wire. it wont shut off with the engine off. it will keep feeding it power. it needs a shut off switch in between the power and the fan motor. so it can go to anything really. if that cool off sensor is in the loop of power to the fan motor.

[Dragon]

Big electric fan discussion

http://www.fordification.com/forum/view ... ectric+fan
My solution to your wiring thoughts. direct off the battery hooked through a thermostat controller.
http://www.fordification.com/forum/view ... an#p467636