2003 jeep liberty 45rfe transmission TCM swap to a 545rfe???

[Kaden5645]

Okay, I'm just curious if anyone has heard or has done this. I heard and read about the 45rfe transmission and the 545rfe transmission being exactly the same besides the programming in the TCM. I've also read and watched some videos on people changing out there TCMs in other jeeps that had 45rfes and turning them into 545rfes. Does anyone know if it's possible to do this with a 03 jeep liberty and if it would make a significant difference regarding MPG and such?

 

[04Liberty]

I know it has been done for fact on older Grand Cherokees and Rams. You are correct, no difference but programming. Theoretically it should be doable (TCM's aren't VIN dependent) but will you actually get any use out of the extra overdrive gear (that's all it does, gives you 5th gear)? I imagine if you spend alot of time on the highway at decent speeds then it might be worth doing.

 

[mercdudecbr600]

Resurrection of this thread for a hot minute because gaining an extra gear when you have a 02-04 KJ + 4.10 gears (seemed) like a decent strategy to upgrade the KJ.

Onto the swap. I put in a 2002 WJ GC TCM PN# 56041905AD (the one every says works on the GC forums) into my 45rfe equipped KJ - I DID NOT GAIN A 5TH GEAR, RPMs were the same at 70mph and I did not detect another "shift". Good news though, this TCM shifted pretty close to the same as before, maybe a little crisper (I also have a shift kit installed). Not a huge investment into it, but a decent experiment.

I know this has been discussed before with some adding that it has do with VIN - the KJ never got the 545rfe - so the TCM won't activate. And this is confirmation of that (sadly).

 

[KJowner]

The CRD's have the 545 with the extra gear so it can be done, no idea how though!
@joshgoble any advise?

 

[mercdudecbr600]

It should be as simple as replacing the TCM, but at this point I’m not convinced it works for a 3.7 kj.

 

[mercdudecbr600]

Flash a 45RFE to a 545RFE- Anyone done it?

So I just found out this past weekend that my 2003 KJ built in May of 2003 actually has a 45RFE ****** (Backwards angled cross member, TCM mounted on passenger fender, 15 bolt ****** pan). I was elated to say the least for many reasons- I've now owned an 02 Ram 1500 4.7, 04 Ram 2500 HEMI, and...

www.jeepkj.com

 

[KJowner]

That explains it