My 04 S60 is having issues where it goes nuts and brake light will come on and the car wants to coast. The computer is giving me TCM failures.
It only happens after the car is hot, making me check out the tiny fan in the module box. The fan movement is unobstructed, and I read 55 ohms across the leads (with the little capacitor or resistor on it, not sure what it is).
However, I am not seeing it get 12vdc with the engine started. Is there a delay, or temp sensor activation or something to that effect? Or do I need to trace the wire? Is there a relay somewhere that could be out? I checked all the fuses in the hood fuse box and didn't see any issues.
I have ordered some electrical contact cleaner and the module removal tool so I can check that side of things soon, but with the fan not running, I am not sure if that is just marking checkboxes or going to fix anything.

 

You might be on the correct track thinking it is heat related - A common problem is the CEM overheats and then the car does crazy stuff. You can test that by removing the underdash panel and maybe trying to cool the CEM with a 12v fan - common failures are courtesy of xemodex.

https://xemodex.com/us/product/centr...ansferservice/

 

I was trying to track down where that fan pulled from.
When you say the underdash, that's on the passenger side? Same panels to remove as the cabin air filter? I changed that filter first time since I owned it a couple months ago, when it seemed like the AC didn't want to work. I am wondering if I did something wrong now.

 

https://xemodex.com/us/pdf/xemodex-c...oval-99-04.pdf