Originally Posted by cadiwa
Does anyone know how to test the 1090385 fan
Controller. Right now it is defaulting to high speed. This setup receives information from the ECM ( no sensors).
Don't know of any way to test the controller, but some things you can check. Disconnect the three wire connector on the controller and see if there is any corrosion or burning of the contacts. You might try a spay electrical contact cleaner if they are dirty. I would also use some silicone grease when re-installing the connector. Just something I like to do when a connector is exposed to the elements. One of the wires goes to ground and you need to make sure it is grounded by using an Ohm meter. I've heard of a bad ground causing this problem. The cooling fan should go to high any time the connector is disconnected.
It is possible to replace only the electrical part of the controller instead of the entire thing. Can save quite a bit of time and money. The part number for the electrical side is 1090384.
Hope this helps,