Hi

I am installing a Derale oil cooler # 15950 with a Derale fan controller # 16749. The wiring for the controller calls for a switched positive to the Yellow wire off the relay. See picture.

I know my coil is a switched positive - But is there another switched positive inside the relay box in the engine bay ?, or is the coil the best option?

Click to view attachment

The coil wire is the only wire accessible from either main connector.

Pin 86 on the power supply relay (also pin I on the fuel injection ECU connector shown in the bottom left) is also a switched power lead.

George, do the instructions say anything about NOT locating the fan controller in the engine compartment? MY Derale unit lasted about 2 years before it shorted out internally. It did not mention that but when I switched over to Dakota Digitals unit it was mentioned in their instructions. I feel the engine heat is what ruined my Derale unit but can't prove it.

My oil cooler came with a thermostat. I installed the thermostat on the outlet side of the cooler and had this control the fan. I used an unswitched circuit with a series fuse. The fan will run after stopping until the temperature is lower. I put the sensor on the outlet because the oil from the engine will always be hot enough to trip the thermostat. The oil cooler will remove some heat without the fan. I let this work until the fan is needed

As long as you are just using the coil wire to activate a relay, that's going to be the easiest way to go.

Thanks guys. I think I'll go with the coil. My unit came with a thermostat as well, but its not adjustable. So I am going with an adjustable thermostat that requires the relay etc.