The Dewitts™ SPAL Wiring Kit is a simple relay harness that comes with all of DeWitts™ radiator and fan combinations. *image from video* For example, above we have a dual radiator fan combination. It comes with two wiring harnesses with the two relay kits. The relay kit has four wires coming out of it. *Closeup from Video* We have our hot and our ground wires. We also have two smaller wires that are coming out. The red wire goes to an ignition source and the gray wire goes to the temperature sensor. In all Dewitts™ radiator and fan combinations, we put the temperature sensor right in the radiator. We put it right under the inlet tube so hot water triggers the fans to turn on at a certain temperature. We do this so you don't have to find a spot in the motor to put your temperature sensor. It's a good spot for a good accurate reading.
We get a lot of questions on the ignition source. The relay needs an ignition source so we want to run that small wire to something that is off when the car is off. When the key is in the off position, we don't want your fans to continue to run after you shut the car off. A good example is something like a windshield wiper motor. A good way to troubleshoot the whole system is by using the ground wire. Take the wire that runs right off the temperature sensor and touch it to your radiator. If your radiator is grounded out properly, then your fans will come right on.