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Unread 05-29-2014, 02:42 PM   #1
McCloudsZJ
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1998 ZJ 
 
Join Date: Sep 2011
Location: Roanoke, VA
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545RFE Reflash or a JY TCM & Torque Management Delete

I found one thread on this from 2010 that had conflicting answers on whether or not this was possible. From my days in the WJ world, I can say that the OD/alternate 2nd gear on the 545RFe is a noticeable improvement over the 45RFE. Has anyone else grabbed a 545RFE TCM from a WJ and used it in the last four years?

Also, do the KJs have the same torque-management buzzkill of a electronic nanny that the WJs do? They'd cut fuel and retard timing at WOT to give nice smooth shifts at WOT. By cutting one little wire, that whole system went away and the 1-2 upshift would chirp the tires.

If this is a topic that's been beat to death, forgive me. At least I didn't ask if I can fit 35" tires with a BB...

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March 2014 GCOTM. 1998 Deep Slate 5.9
On the Jeep:Hot intake, 52mm TB, Summit 8mm wires, catch can, 703s, insulated fuel rails, indexed Champions, Bilstein 4600s, Eibach lowering springs, Moog SS, Ironman mounts, Lotek 2GP, lots of gauges, sparkly paint.
In the garage: M1 4bbl
In the works: Addco/Hellwig sway bars, nitrous, full polly bushings, full exhaust, data logging, billet UD pulleys
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Unread 05-30-2014, 06:30 AM   #2
McCloudsZJ
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1998 ZJ 
 
Join Date: Sep 2011
Location: Roanoke, VA
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Enough googling and I found the answers to my questions...

TORQUE MANAGEMENT DELETE
Quote:
***Models with 45RFE only***

I followed what the 4.7 dodge guys had done. I used their instructions and the FSM wiring diagrams to stop the ignition timing retard at shifts on my KJ. There is a wire (yellow with green tracer stripe) that signals the PCM when to retard timing. Simply snipping the wire removes that communication and stops sloppy shifting. I did it and so far I am impressed. Before the snip you could feel the Jeep slow down even before the shift. Now, at part throttle the shifts seem "neutral", the Jeep doesn't lurch forward but it doesn't slow down either. At WOT the shifts feel nice and positive (Jeep lurches forward slightly).

It seems to have no effect on transmission longevity as there are some that have 150K+ with no problems, no check engine light either.

So, unscrew and remove the wiring harness from the TCM, then take the plastic cover off. Snip the #10 wire (it is yellow with a green tracer, see bellow for connector pin out), make sure you are snipping the proper wire as some people on the dodge forums have accidentally snipped the #17 wire (yellow w/ dark blue tracer). If you snip the #17 wire than the trans will shift way to hard. Reinstall the connector onto the TCM, reinstall the screw, then reinstall the plastic cover.
That's it!
These guys for future reference:



545RFE TCM:

Quote:
It's been tested a few over the years, using newer TCM's with 5th enabled in older 45RFE vehicles. The TCM's for the 45/545RFE are basically the same hardware, with several versions of software over the years. Some have tried taking the TCM from a 545RFE Grand Cherokee and installing it in 45RFE equipped Liberty's only to find that 5th gear (.67) OD did not activate.

I've personally installed a 2005 Liberty CRD 545RFE 5 speed TCM in my 02 Liberty and found the same result. No 5th gear and increases sloppiness in shift quality over the 02 Liberty code. I found a hint as to why in an old DC transmission training manual (that I no longer have). The ECM to TCM communications on startup includes an interrogation message by the TCM to the ECM, to determine the vehicle model it's in. The TCM has more than one set of shift maps installed, so they say in the training course. When it derives the vehicle type (from the VIN IIRC), it uses the correct shift map for that vehicle. This enabled the same basic hardware in a range of model years to be used for the same transmission in Jeeps, Dodges and possibly other 545RFE equipped models.

The training course details how the correct shift map is derived by the TCM once it "knows" which vehicle it's in, not whether the 2nd OD is enabled or not.

This seems to be because the same 2005 CRD 545RFE 5 speed TCM only uses 4 speeds in my 02 45RFE. It apparently worked on the 99-2000 models of Jeeps and some Dodges when fitted with a newer software TCM because the VIN range fit the newer maps that were supplied with the TCM's sometime in 2001.

I know of one case where a CRD owner tested a Dodge 545RFE TCM in his vehicle and found that the 5th gear was still enabled, but the shift points were at lower rpm's on some gears. Clearly, if the TCM programming doesn't have a later model VIN range to match with, it still uses a set of shift maps.

I'm guessing that it's possible that if you found an older TCM(circa 2001) with 5th gear enabled, it might not have the VIN range for the Liberty in it and may default to something other than what the 2002 and early 03 Liberty's used.

It would cut down the range of TCM's to look at because if the training manual is correct, if the software knows the 2002-03 Liberty 45RFE VIN range, it's going to use the correct shift maps for the 45RFE.
So, looks like torque management delete is on the list of things to do, and the 545RFE flash is not.

__________________
March 2014 GCOTM. 1998 Deep Slate 5.9
On the Jeep:Hot intake, 52mm TB, Summit 8mm wires, catch can, 703s, insulated fuel rails, indexed Champions, Bilstein 4600s, Eibach lowering springs, Moog SS, Ironman mounts, Lotek 2GP, lots of gauges, sparkly paint.
In the garage: M1 4bbl
In the works: Addco/Hellwig sway bars, nitrous, full polly bushings, full exhaust, data logging, billet UD pulleys
McCloudsZJ is offline   Reply With Quote




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