wk Grand Cherokee cooling fan

Hi all.
I have been given a 2014 Jeep Grand Cherokee to fault find an inoperative radiator cooling fan. It is a diesel with electric cooling fan. Car was involved in accident and cooling fan was replaced due to the shroud being cracked and broken. The fuse and relay in the main fuse box are not there and look like they are not supposed to be. The wiring diagrams I am looking at dont match the wiring that is available. The code relating to this issue is P0480.
The other confusing issue is the old fan assembly was in the boot so I thought I would try to test it to see how it worked. It would not run with a straight battery connection. It has 3 wires. A thick red and thick black and a very thin green wire. I wanted to check resistance and had 0 ohms so set the DMM to volts and the two thick wires gave a reading of 12v. The wires were not connected to anything?? If anyone has some insight into this system it would be appreciated.

Cheers.

Cancel the help request. Figured out what was going on.

Glad you figured it out! If you have a chance, would you care to post the solution? It could help someone in the future trying to diagnose a similar issue.

Noah wrote: Glad you figured it out! If you have a chance, would you care to post the solution? It could help someone in the future trying to diagnose a similar issue.

Not a problem Noah. All for helping where I can.

The short answer is that the second hand fan had an open in the control side of the module which is integrated in the body of the fan.

The request for help was because none of the wiring diagrams and information I could access matched what was in front of me. I believe that all my info related to the petrol versions of this vehicle. I like to be prepared when diagnosing vehicles and this situation threw me hence the help request. Once I slowed down and had a think about what was in front of me it became clearer that I was approaching the situation wrong. I had tried to run the old fan to work out how it functioned.
New plan. Obviously the 2 thick wires were power and ground, but which one was switched? Neither. Solid 12v on the red and solid ground on the black and both able to carry current verified through both a load pro and a high wattage test lamp. The small green wire was my concern. Clearly it was the turn on signal but how did it function. Hooking p a meter and using scan tool to control the fan I had a voltage drop from 3.5v to 2.7v on the low setting and to 2.1 on the medium setting. That then prompted me to bring the scope into play to see what type of signal I had. This fan was Duty Cycle controlled. So good power good ground and good signal, faulty fan module. This was verified by rigging up some jumper leads to the original fan and bi-direction ally controlling the fan operation again.

Moral of the story don't panic and take your time to think things through especially if you are unsure of how a circuit operates. It will come to you.
My only query after everything is why the original fan power wires had 12v when unplugged from the system. That voltage did drop to around 8v after 1/2 to 3/4 of an hour later. I thought any power contained in capacitors would have drained fairly quickly. Something to investigate at a later stage.

Cheers