When I installed my Power FC, I noticed there was a little black box also wired in right next to my stock computer that said "control unit" on it. I decided to just leave it connected at first, but my fans seemed to run way after I shut my car off and would eventually drain my battery. I currently have it disconnected and everything seems to be running fine(fans included). Anyone know what this thing is?

 

It is the controller relay for the fans it's job is to run the fans after shut down when coolant temp is at a certain temp or higher. It runs your fans for up to 10mins after shut down. It won't effect your battery in any bad way. It was part of the coolant recall.

 

I figured it was probably related to the recall. My battery died the day after I installed my PFC, and since I disconnected this control unit it hasn't, so I'm pretty sure that this is what caused it. Perhaps it doesn't interact with the PFC well or something???

 

Perhaps your battery is bad or going bad! No one else has had this problem. I am running the N-Tech mini battery and it has less power reserve than a normal battery. My battery does not go dead even when I use the fan mod switch to turn the fans on for 10 minutes post engine turn off.

 

There should be a ring terminal ground wire coming out of that black box. If you don't connect it your fans will run forever! (if I remember correctly. Be sue this ring terminal the ECU ring terminal are both grounded properely. They both screwed into the stock ECU mounting bracket (top one).

 

Hmm, faulty ground seems like the leading suspect. Thanks once again spyfish

 

Let me know if this was the problem.