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Old 02-14-2014, 11:41 AM   #1
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Programming JK PCM to Recognize 4:1 Transfer Case

Does anyone know if Jeep dealers can program the Wrangler JK Powertrain Control Module (PCM) to accept a different transfer case ratio for late model JKs?

I just installed a 2013 Rubicon transfer case into my 2013 JK Sport. I'm experiencing an RPM limitation problem while in Low 4. This is a known issue for late model JKs when transplanting Rubicon transfer cases into a Sport model. At least for those with automatic transmissions. I took my JK to a local dealership but the mechanic said he didn't think his factory diagnostic tool could actually program the new ratio. He did say that he'd be willing to give it a try if he knew how to do it.

I'm aware that there are other programming options out there like waiting for the new AEV Hemi Procal, getting a Superchip Flashpaq, or shipping the TCM off to Dakota Customs to name a few. I'm looking for 'while you wait' instant gratification from a dealership if possible.

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Old 02-14-2014, 02:03 PM   #2
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They probably can, they might say no, but its going to cost almost the same as buying a programmer. superchips flashcal can do it, i presume aev procal can.

Dealers around here charge about $100 to do this kind of thing....

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Old 02-15-2014, 05:24 AM   #3
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My dealer is willing to but they said that they don't know the process for actually making a transfer gear ratio change. They hooked up their factory tool and poked around and could see the old gear ratio but didn't know how to change it. It's a good dealership. They spent about a half hour of labor and didn't charge me. They said if I get the instructions they'd do it. Cost would be $140.

Regarding the AEV Procals. I own one that's less than a year old and it can't change the transfer case ratio. I spoke with them on 2/10. Their new 'AG Level' Hemi Procal can make the change but these haven't been released to the buying public yet. Could be weeks or longer. Cost will be about $160.

Dakota Customs will do it for me. Cost is $125 but I have to send them the TCM.

I just checked the Superchips website. There's nothing in the literature that says the FlashCal can program transfer case gear ratio. I'll give them a call though. Now the FlashPaq can do it but that's $350. Besides the cost, I've heard scary stories the FlashPaq's. I'd definitely want to make sure that it doesn't mess with any other PCM setting.
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Old 02-15-2014, 01:55 PM   #4
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My flashcal positively does it. has transfercase high and low ratios you can change. I actually plugged it into my jeep just now and looked for it, its under "vehicle functions" like everything else.
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Old 02-21-2014, 03:46 PM   #5
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My flashcal positively does it. has transfercase high and low ratios you can change. I actually plugged it into my jeep just now and looked for it, its under "vehicle functions" like everything else.
Closing the loop. Just purchased the Superchips Flashcal. It took less than 5 min to make the change. Thanks, MichiganAdam.
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Old 02-21-2014, 03:52 PM   #6
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AEV has released the latest procal that can program the transfer case swap. It was announced a few days ago on AEV's forum.
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Old 02-21-2014, 03:53 PM   #7
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Closing the loop. Just purchased the Superchips Flashcal. It took less than 5 min to make the change. Thanks, MichiganAdam.
that is a great upgrade. I looked for over 6 months for a 4.1 t/c and could not find one other then new.
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Old 02-23-2014, 04:21 AM   #8
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My dealer is willing to but they said that they don't know the process for actually making a transfer gear ratio change. They hooked up their factory tool and poked around and could see the old gear ratio but didn't know how to change it. It's a good dealership. They spent about a half hour of labor and didn't charge me. They said if I get the instructions they'd do it. Cost would be $140.

Regarding the AEV Procals. I own one that's less than a year old and it can't change the transfer case ratio. I spoke with them on 2/10. Their new 'AG Level' Hemi Procal can make the change but these haven't been released to the buying public yet. Could be weeks or longer. Cost will be about $160.

Dakota Customs will do it for me. Cost is $125 but I have to send them the TCM.

I just checked the Superchips website. There's nothing in the literature that says the FlashCal can program transfer case gear ratio. I'll give them a call though. Now the FlashPaq can do it but that's $350. Besides the cost, I've heard scary stories the FlashPaq's. I'd definitely want to make sure that it doesn't mess with any other PCM setting.
I find that very surprising. The vast majority of dealers will only do what is in the "book". You JK is clearly a non-factory configuration although obviously it is mechanically possible.

You might also be able do it indirectly via the differential gear ratio.
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Old 02-23-2014, 08:49 AM   #9
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I just installed a 2013 Rubicon transfer case into my 2013 JK Sport. .

Just curious now that you have it programmed. How did you come about a 2013 Rubi Transfer case if you don't mind telling us?

I am thinking you either got real lucky or know someone, other than that you may have bought it new. If so what was the cost? Just being nosy because a case that new is like a gold brick? Hard to find. Did they want to sell the rubi axles too?
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Old 02-23-2014, 10:11 AM   #10
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Just curious now that you have it programmed. How did you come about a 2013 Rubi Transfer case if you don't mind telling us?

I am thinking you either got real lucky or know someone, other than that you may have bought it new. If so what was the cost? Just being nosy because a case that new is like a gold brick? Hard to find. Did they want to sell the rubi axles too?
mototech in Las Vegas does LS conversions and they trade out new rubi t/c for 2.72 t/cs for $500 because the LS conversions won't work with the rubi t/c.

you send them your 2.72 t/c and $500 they send you the 4.10 t/c problem is I had an automatic 2013 so I was limited. if you have a manual they have no shortage I guess.
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Old 02-23-2014, 10:32 AM   #11
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Did you put a 2low kit in it while you had it on the bench?
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Old 02-23-2014, 04:53 PM   #12
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mototech in Las Vegas does LS conversions and they trade out new rubi t/c for 2.72 t/cs for $500 because the LS conversions won't work with the rubi t/c.

you send them your 2.72 t/c and $500 they send you the 4.10 t/c problem is I had an automatic 2013 so I was limited. if you have a manual they have no shortage I guess.
Thanks for the info. I am in the same boat as you are with the automatic. That is an unbelievable price. Is there a lot to swapping one out?
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Old 03-06-2014, 07:27 AM   #13
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Whats the point in a 2low kit? Im a little curious about the rubi tc kit myself.
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Old 03-06-2014, 08:26 AM   #14
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Whats the point in a 2low kit? Im a little curious about the rubi tc kit myself.
2 low would be very good in a rubicon for steep sketchy down hills as well as some places where you have good traction and don't need 4 wd but want to inch along without riding the brakes. There are plenty of places in Moab where it would be ideal.
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Old 03-06-2014, 10:54 AM   #15
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JK Rubicon xfer case is 4:1. Non-Rubicon is 2.71:1, I think. It's a noticeable change and quite nice to be able idle across a rocky technical section of trail. There are buggies out there that use crawl boxes with 100:1 ratio. You can also improve crawl ratio through a differential ring and pinion change. You can calculate your crawl ratio here Jeep Ratio Calculators under the Gear Calculator tab.

I saw a buggy driver running a super high ratio get out of his buggy while it was crawling and just walk along side of it as it inched along. Maybe not the safest thing to do but still pretty impressive.

Having a Rubi xfer case is not without its drawbacks. I could wheel all day in my old low 4. Now I find myself having to go into Hi 4 on the faster trails and hill ascents because low 4 winds out too quickly. When I lived in the desert and did pre-runner type wheeling I never used low 4. Out here in the mid-Atlanitc I use it a lot. Hope this helps.
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Old 03-06-2014, 04:02 PM   #16
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i know it's 4:1

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