I recently came to realize 2002 was the only year the 4.7L ram came with the 45RFE programming but I know it's physically the same as the 545RFE. At just over 70mph my rpm's are at 2200 so I would like to get the extra OD gear to help bring them down. I struggle to get 15mpg highway, partly because of the 3.92 gears and the missing airdam. I want to know if I can just swap in a 2002 Grand Cherokee 4.7 TCM like all the Dakota/Durgano guys do to get the extra overdrive gear. Is it simply just unplugging the old TCM and installing the new one, or is there more to it? I went to the stealership and asked if they could check for updates and they wanted $90 just to see if its possible. So now I have lost all faith in them once again. I know it's not gonna sip gas like my old car but I think I have some room for improvement, any suggestions are appreciated.

 

Someone on here did it (hopefully he chimes in) but if I remember correctly he just plugged in the TCM and the gear was there.

 

Ok I am officially confused, are you saying there is another gear in our transmissions (mine is an 2002 also) that is not being used? as in 1st, 2nd, 2nd prime, third, OD, and another OD that is not programmed to be used? That is the way I read this post!
or are you having to swap in the 5 speed double over drive trans and new control box?

 

Yes, there is another physical gear ratio in the trans that was not used in our 2002 4.7 rams. The 1999-2000 grand cherokees, and early dakotas and durangos have the same trans as well but the update was only released for the grand cherokees. Us dodge guys were left out on that one so I'm basically trying to find a way around it. Once the new TCM is installed my trans will have 1st, 2nd, 2nd prime, 3rd, 1st OD (4th), and 2nd OD (5th).

 

The 545 isn't built like an old school hydraulic transmission. It's fully electronic, different parts mate up to make the gear ratios. Someone calculated out one time and with the right programming (that's the only difference, not physical gears) it is capable of something like 12 fwd gears & 2 reverse. 2 prime isn't in the normal shift schedule, only when you floor it to drop it down.

 

It is a very advanced trans for its time, just a little too soft for my liking. Does anyone else know if the 545RFE TCM from the 02 grand cherokees is plug and play? Either way I plan on picking one up at the end of this semester in 3 weeks to test it out.

 

Below is a link to the post that got me thinking about this. The only thing that confuses me is why he had to send in the TCM for an update. All of the dakota and durango guys just plug in a 2002 grand cherokee TCM and thats it, so I'm not sure if theres a different between them and the rams that would require a flash. You gotta take the space out of the url below when you paste it into your browser for it to work.

www.dodge talk.com/forums/showthread.php?t=208132

 

I did the Torque Management delete on my truck. Would I have to re-enable it if I were to do this swap?

 

No, pulling the TM wire won't affect the extra OD gear.

 

OK, I'm in. I wanna try this...