Ok. It started at the end of last summer, 2024. I was driving my XKR 2003, home and it started to over heat. Got home 1/2 mile away and checked under the hood. The slow speed fan was running, the bigger high temp fan was not.
I tried buying an XK8 fan, all i could find. I swapped the bigger fan and motor. It turned, but very slowly.
OK, back to the parts search, found the proper fan shroud assembly and put it in. I had to take off the radiator high right side hose to get it out and back. Warning it's fiberglass and that wasn't pleasant.
New fan worked, thought I was done, but NO.
XKR was overheating again! Fans worked, must be something else. Thermostat! I went to pull it and a torex screw stripped right out. I was just jogging back and forth to work, cooler temps setting in for winter... I forgot about it, until one day making an airport run. It got hot, and cooled before I could pull over. Ok it's great working! It lasted a few months... then again overheating. Yes it's a long story. Ok got a drimmil and gouged me a slot for a big screw driver. Got it out. Cleaned it up! New Thermostat! And I should be good!
Well no. I noticed a puddle in front of the car. I got it home. So when I did the Thermostat, i hadn't noticed i accidently looped a part of the hose over the dipstick. This pulled another part of that octopus hose into the pulleys. A hole was warn in the hose! Ok back to parts search. Got a hose wrangled it in. Put in more antifreeze and.... now the hose isn't leaking, but the fans are not running!!!
I checked the big power plug going to the fans, 12-14 volts. I checked the small plug it's giving 12v. I checked the outputs of the module, 0.06 volts.
I grabbed my old fan setup and plugged that in... nothing ran. Checked the module output, 0.07 volts.
I hope someone who knows has a good suggestion. I checked the temperature probe, it was sending to the gauge on the dash, it went to the middle. I pulled the plug off of the probe, the motor ran a bit faster.
Any ideas? I also found the antifreeze a bit low in the tank... maybe air pockets?
I saw there is a relay under the front end, but i am already getting power.

 

The octopus hose is in the rear 2 ft from any pulleys....???

I have my fans wired to run at half speed 24/7 and the full speed switched for motorway cues.

 

I had a fan issue with my 97 xk8 right after I bought it. Blew three of the 30 am fuses in one ride so I put a forty am in to get home. I took the whole assembly out and noticed that one fan was spinning very freely, and one was very sluggish. I removed the sluggish one from the shroud and carefully remove the fan blade. I then opened up the motor cases, looking at it it appears it can’t be opened, but you need to bend all the tabs carefully on the back side of the motor where the plug is and carefully pry the cover off. When I did that the whole inside of the fan motor Was caked in black grime and dust. I carefully cleaned it all out and lightly sanded the router contacts and clean the grooves in between them, as well as the rest of the motor. I reassembled carefully, bending the tabs back in place after oiling the bearings and reinstalled. I I do remember going over the wiring and I can’t say for sure but I think there was some sort of ground connected on one side of the shroud that I removed sanded, cleaned up and reinstalled put back the 30 amp fuse and never had a problem again. I don’t recall any of the readings while checking everything, but if your fans are spinning freely, and you’ve checked the fuse and the relay which check out to be good, then I would lean towards wiring such as faulty ground or an internal motor issue where it’s not making good contact with the power coming in.