Which sensor do you go off when wiring in a manual switch for the fans?

The fans are getting a constant live feed so they can't turn off. Start by rechecking the wiring and the connectors for the fans and the sensor.

The cooling fans should come with a sensor and tells fans to come on at certain temperature

first check fluid lvl then check fuse for fan then unplug temp sensor switch and use jumper wire in the wire socket fan should come on if not check temp sensor switch.

this is a fairly easy fix, just takes a little trouble shooting. first ensure all wires and connections are in good shape. if that checks out ensure all fuses and relays are in working order. if all that checks out then its only one of two problems. 1. the fan switch runs on a seperate temp sending unit and its gone faulty 2. the fan motor is at fault. you can check the fan motor by jumping the switch and running a direct power source to it. if it runs then its a sensor or other problem. if you need it fixed on the cheap run an alternate power wire and install a switch inside the cab, when you seen the temp rising turn on the switch manually and off again when it cools down. or you can track down the appropriate sensor and replace it.

yes just take the wires off the motion sensor and wire nut the two wires you took off the sensor together.

First thing you should do is test the fan.Just unplug it and then run jumper wires directly to the battery.Be careful to keep your hands and wires clear of the blade.If the fan turns with power applied directly from the battery then its ok(dont worry about pos or neg for this test as a dc motor doesnt care about polarity and will just spin backwards if you get it wrong,the objective is to see if it works) If the fan works then you should move to the fan relay.This should be located in a "fuse" box in the engine compartment and its position will be listed on the inside of the cover.Most relays in these panals are the same,simply pull the fan relay and swap it with a similar one.If the fan now works,replace the defective relay(dont forget that the engine must be up to temp before the fan will kick in)If all this fails than you are most likely looking at a faulty temp sensor or wiring.A decent manual such as a haynes or chiltons will show you the position of this sensor(I can only assume you have a 3.1l engine)

Yes. The incoming hot wire should connect to the sensor switch with a wirenut. Put another wire under that wirenut and jump it over to the fan switch.

Hi and welcome to FixYa,

To my understanding, the cooling fan is activated by the ECM. This is done by switching the yellow/black wire to ground. The activation is triggered by the coolant temperature sensor that feeds signals to the ECM. Ideas to consider:

• verify integrity of connections of coolant temperature sensor (purple/black & purple/green wires) to the ECM;
• check, clean or replace the coolant temperature sensor itself;
• bypass ECM and install a manual override switch plus dual reverse protection diode on the 2 yellow/black wires from the cooling fan wire connector.

Good luck and thank you for asking FixYa.

check temp sencer wire at bottom of raditor

The water temp sensor is a switch that closes the circuit when the temp reaches a certain level and that switch sends power to the fans. Either your water temp sensor is faulty (always on) or the wiring from the sensor is shorted out. 
The easiest fix would be to replace the temp sensor. They are cheap, and replacing it will likely fix the problem. Your local parts store can get you one and show you where it is located on your car. 
If it doesn't fix your issue, at least you'll have eliminated that from the problem and can search for the short in the wiring. 
If you know basic electrics a simple auto circuit tester (cheap at any auto parts store) or multimeter will help you trace the short. If you're competent with electronics, you can always wire the sensor to the fan independently of the car's wiring harness to workaround the short. Be sure though that you have a workshop manual with a wiring diagram and that you make the correct connections to the switch, fan and the car's 12V power.
I'll bet that replacing the sensor will take care of it though.
Hope this helps.