I had a thread about this once before, but I just wanted to ask about it again. Vehicle is a 2001 Durango SLT 4x4 4.7L with the 45/545RFE. It's a No communication with TCM from PCM code, but my transmossion shifts perfectly fine. This code made its presence known after I did the 2002 Grand Cherokee 545RFE TCM swap. I have never had a problem with the transmission, and like I said it shifts fine, so what the hell can it be? I've already taken the plug out and cleaned both ends with electrical plug cleaner but it still comes about in the winter. I'd absolutely hate to sacrifice my 2nd O/D. Hopefully MasterTech can pop in and share his wealth of knowledge with me.

Thanks in advance!
-Joe

 

hmmm... could it be your running a tcm thats for a jeep not a durango? i wonder...

 

But why would it tell me there's no communication if both vehicles utilize the same communications system?

 

my guess is that they both use the same communication system but there is something slightly different with the pcm's. have you reset the code? how long does it take before you throw the code after resetting?

 

It usually only comes around when it's cold out, like around 30 degrees or so.

 

wait 2nd overdrive?? explain yourself

 

Subscribing for curiousity.

 

the 45 and 545 are the same transmisison as far as the physical parts go

the 45 is a 4speed overdrive trans 1-2-d-od
the 545 is a the same 4 speeds with a 2nd od gear

ratios go as follows
1) 3:1
2) 1.67:1
2') 1.50:2
3) 1:1
4) .75:1
5).67:1

double overdrive bc two gears below 1:1

the difference is the transmission controller programming

 

Exactly as Shrp said. The early Jeeps with the 4.7s had the 545RFE programming but the Durangos did not. With that being said, the TCMs are the same, just different programming.It will work correctly with 4.7 Durangos from 2001 to 2002 if you use the TCM from a 2001 to 2002 Jeep Grand Cherokee TCM. It's simple plug and play. The major differences are that with 3.55 gearing, O/D will kick in at 50 MPH versus 40-45 MPH with the 45RFE TCM, and also the 2nd O/D which kicks in about 65 MPH. With 3.55s you can easily cruise at 75 MPH and still be under 2k RPM. (All of these are with 3.55 gearing, and 16" rims with 31" tires)

 

not quite, mid year 2002 they changed the PCM on these trucks to the NGC (4 plugs on the PCM), the NGC incorporats the TCM and PCM into one unit, these are already set up for 5 speed function,

you are correct when referring to the 01-late 02 which have the 3 plug PCM