Good evening folks,

I have searched around the various forums, google, and even a few Dodge forums, but I haven't found an explicit answer to this question:

Can the 45RFE transmission in a 2002 Liberty Sport 4x4 be flashed to 545RFE spec? If so, will the dealers do it? Are there aftermarket options?

The data I have thus far is that there is a flash for the 2000-2001 GC to enable the 5th gear OD, but no mention of the Liberty. I would expect that, for on-highway use, the flash (if available) wouldn't hurt anything and might help get a bit more out of a tank of gas. Yes, I know it's a heavy truck and I know it's primary goal is not ultimate fuel efficiency. Still, I do commute with my Liberty and if a minor upgrade can make a positive change with no downside that I can see, why not do it?

Has anyone any info on whether this is doable, or have any of you hacker types have flashed with the GC firmware successfully?

My apologies if this has been asked a few dozen times, but my searching turned up no results related to the Liberty 45RFE.

Thanks.

m

Not possibe,the 545RFE is really a 6-speed auto(still two 2nd gears with one a downshift only,and 2 OD ratios),the 45RFE is really a 5-speed auto(two 2nd gears with1 a downshift ony and 1 OD ratio).The flash for the Grands(if they have the 45RFE) only will unlock the second 2nd gear for the normal upshift and downshift.

From everything I've read, the 545RFE and the 45RFE are internally identical. there's a guy that swapped a Hemi into his '00 Dakota and used the 03 Hemi's ECM with his 45RFE's TCM and it gave him an extra forward gear. Aren't there 8 forward and 3 reverse potential ratios for both the 45 and 545?

tjkj and Thunderbird, thanks for the response.

This link:

http://www.jeepiki.com/wiki/index.php/45RFE/545RFE

...and others I have found indicate that the two transmissions are, in fact, the same hardware.

And this GC forum discussion has additional info:

http://www.jeepsunlimited.com/forums/sh ... p?t=733991

And here is a Dodge Dakota forum posting with information regarding the GC Service Bulletin which references 'enabling' the 5th OD gear.

http://www.dodgedakotas.com/boards/gen/23574.html

Of course, none of the above is rock-solid evidence that the 45RFE can have the 5th OD enabled for every 45RFE built...

m

Ive also read about getting the flash done on the grands. Seems like any dealer can do it if they want/know what their doing.

Ive always read that the 45rfe and the 545rfe are the same also.

_________________
LOST KJ'S
Where are you going???
Current Jeep: 2004 Jeep Liberty
-Atlantic Blue
-Air Ride Rear Suspension ; OME/Rustys Lift ; Powertrax Locker ; Moog Lower Ball-Joints ; 245/70/16 Yokohama Geolander A/T-S's on MOABS ; Flowmaster 50 SUV
Lost #007082
http://www.cardomain.com/id/jeepjeepster

I'd kill for another overdrive.

Did they change the TCM from the '99-01 and the 02-3 45RFE? Maybe it was just on the first couple years of the 45RFE, and the newer TCM can't take the same flash?

Just looked in the part manuals,some parts are different in the 45RFE and 545RFE.The input carriers are different which will give different ratios between the two,although the rear planentary gear packs are the same other parts are not.Oh this was comparing the 45RFE from a '02 KJ and a 545RFE from a '06 KJ CRD.

I've asked B&G, APS, and my transmission mechanic and they all have told me that the two transmissions are very close, but they are different and it won't work. I wanted it while I'm running 4.10 gears and 29.5" diameter tires so I'd have the second overdrive with the .67:1 ratio instead of just the .75:1 that I have now. Would probably gain me a couple mpg at interstate speeds, but the cost of swapping the transmission could never justify it. Now that I'm going to 31.1" tires, the .75:1 should put me at just about the right rpm on the interstate so I'm not worried about it anymore. Plus, if it puts the rpms too low, I would think it might switch constantly between the overdrive gears, and back to 3rd through hills.

_________________
June 2001 Liberty Limited 4X4
Frankenlift II Premium, Al's Upper Arms, 245/75R16 C Silent Armors on Moabs, RL Skink Super Sliders, Rear DTT, Riddler Diff Cover, Fastman Throttle Body, Profinish-Proglass Hood, Borla Dual Outlet Exhaust, TransGo Reprogramming Kit, APS Stall Converter, 4.10 Gears, B&G Chrysler PCM, Lots of Line-X, etc...

What about the 545 in an 03 Hemi Ram? I'd imagine some parts would be different in the CRD because of the torque curve being so drastically different and it'd need different ratios

From what I have read in the CRD section the 545RFE in the CRD's is from a Hemi Ram,that's why they are having so much problems with the trannies,the peak torque curve is 2000rpm lower in a CRD then in a HEMI Ram.Plus the 45RFE and 545RFE have the same gear ratios execpt the 545RFE has the 0.67 2nd overdrive,all other ratios are the same.

Thanks for clearing that up...that's what I get for assuming a corporation would think logically

don't sell the former DC corp short....the TSB says it can be done on a GC....you would have to find the right person to talk to at the dealership. i think most would be reluctant to flash a computer with a program for a different one, but i think it could be done. The worst that could happen would be your TCM would be toast, right? anybody have an extra one laying around??

i wonder if we can steal a TCM from a GC with a 4.7 and the correct year and pop that in the Libby? I think the GC i got my evic from was an '01 with a 4.7, i'll have to see if they still have it.

Yes you can. I did it last night and now have a second overdrive. I really like the way it shifts now. I get the shift to 5th just below 50 mph and it holds down to about 43. I used the TCM from an '03 Grand Cherokee with the 4.7/5-45RFE combo. The service manual said that the pressures where the same for the GC 5-45RFE and the Liberty 45RFE. The HEMI 5-45RFE has higher line pressures. The transmission service manual also indicates that the extra gear is activated by applying the 2C clutch instead of the 4C clutch in combination with the OD clutch. I'll have to do some additional driving to see if there is any boost in mileage.

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'03 Sport
Grand Cherokee TCM, Skids, Superwinch EPi 9.0 in cradle mount with 125' 5/16 Viking Trail Line, Mopar Rock Rails, Trac-Loc Diff, Frankenlift in front and Skyjacker/JBA springs out back, Monroe Reflex Shocks in rear, JBA Gen 4.5 Upper Control Arms, Moog LBJ's, 245/75/16 Goodyear Wrangler Duratracs.

Looking forward to the next report on that one.BTW what did the TCM cost you?

_________________
'02 KJ sport
3.7 V6
45RFE/NP231J
Frankenlifted
Powertrax no-slip
Cook Bros. Diff guard
Skids front to back
RRO rock rails
10LB PowerTank
245/75-16 MT/R

Found it on http://car-parts.com and it was $65 shipped.

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'03 Sport
Grand Cherokee TCM, Skids, Superwinch EPi 9.0 in cradle mount with 125' 5/16 Viking Trail Line, Mopar Rock Rails, Trac-Loc Diff, Frankenlift in front and Skyjacker/JBA springs out back, Monroe Reflex Shocks in rear, JBA Gen 4.5 Upper Control Arms, Moog LBJ's, 245/75/16 Goodyear Wrangler Duratracs.

Was it plug-n-play?Found one close by.

_________________
'02 KJ sport
3.7 V6
45RFE/NP231J
Frankenlifted
Powertrax no-slip
Cook Bros. Diff guard
Skids front to back
RRO rock rails
10LB PowerTank
245/75-16 MT/R

Yes it was. These are the steps I took:
Disconnect the positive battery cable. The TCM is mounted to a bracket on the right side inner fender. It bolts to the bracket from the backside, so I had to remove the bracket. Disconnect the cable from the TCM before unbolting the bracket. Swap the TCMs on the bracket and reinstall. Reconnect the cable to the TCM. Next, with the battery cable still removed, I turned the key to start and held it for 12 seconds. I repeated this step. This is to clear the learned adaptive shifting and reset the PCM as well. Now i reconnected the positive cable and started the KJ. I let it sit at idle (not touching the accelerator at all) until it reached operating temperature. Shut it down and started it again, this time shifting into each gear. Shut it down again, restarted and took it for a test drive. Drove around city streets taking it easy at first so that the TCM and PCM could learn the basics and then took it on the highway. Now I drive it like normal.

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'03 Sport
Grand Cherokee TCM, Skids, Superwinch EPi 9.0 in cradle mount with 125' 5/16 Viking Trail Line, Mopar Rock Rails, Trac-Loc Diff, Frankenlift in front and Skyjacker/JBA springs out back, Monroe Reflex Shocks in rear, JBA Gen 4.5 Upper Control Arms, Moog LBJ's, 245/75/16 Goodyear Wrangler Duratracs.

Wow, everyone told me this absolutely wouldn't work. Glad you didn't listen. So, what is the RPM change at highway speeds with the extra overdrive? I would really be interested in this now that my gas milage is terrible with the lift and heavy tires. A couple hundred less RPM at highway speed should make a lot of difference for me with the 4.10 gears. I'm quite familiar with replacing the PCM and getting it to relearn, so a TCM swap would be rather easy. I have the Transgo reprogramming kit in mine, but that shouldn't matter since it is the same one for the 45RFE and 545RFE.

_________________
June 2001 Liberty Limited 4X4
Frankenlift II Premium, Al's Upper Arms, 245/75R16 C Silent Armors on Moabs, RL Skink Super Sliders, Rear DTT, Riddler Diff Cover, Fastman Throttle Body, Profinish-Proglass Hood, Borla Dual Outlet Exhaust, TransGo Reprogramming Kit, APS Stall Converter, 4.10 Gears, B&G Chrysler PCM, Lots of Line-X, etc...

It's about 200 RPM.

_________________
'03 Sport
Grand Cherokee TCM, Skids, Superwinch EPi 9.0 in cradle mount with 125' 5/16 Viking Trail Line, Mopar Rock Rails, Trac-Loc Diff, Frankenlift in front and Skyjacker/JBA springs out back, Monroe Reflex Shocks in rear, JBA Gen 4.5 Upper Control Arms, Moog LBJ's, 245/75/16 Goodyear Wrangler Duratracs.