Hello All,

I have been experiencing some odd shift patterns and poor shift control in my 08 Unlimited with Auto & 3.73's.

I have scheduled a "ride along" with a dealer tech next week to showcase the abnormalities and I was wondering if anyone else has experiance with TSB 21-018-08 REV. A, and if so, or any other re-programming; what were your findings?

I have heard some Dodge Nitro owners with the 42RLE 4-speed transmission have had some success with it.

What I have noticed:

- Very quick to upshift to 4th/OD even while uphill and attempting to accelerate (while depressing accelerator), this causes a massive downshift when system hits a threshold of <1000 rpm and once the pedal is on the floor.
- Attempting to run in 3rd only by activating the "OD OFF" button does not function, trans will still try to force 4th/OD with button on. (not fun with a full load of people in hilly area)
- Attempting to force run in "2nd" with gear selector in "2nd" will not function, transmission will continue to upshift to 4th/OD and downshift quickly. (causeing overheating concerns.)

**I should note that these conditions are nowhere near as noticeable when I am on flat, straight road with no hills, or not hauling/towing.**

 

NUMBER: 21-018-08 REV. A
GROUP: Transmission
DATE: September 17, 2008

SUBJECT:
Flash: Diagnostic Trouble Code DTC P0740 Or P1798 And Automatic Transmission Shift
Improvements 1-2 Or 2-3 Cold Shift Improvements

OVERVIEW:
This bulletin involves selectively erasing and reprogramming the Powertrain Control
Module (PCM).

SYMPTOM/CONDITION:
The software contains the following improvements:
· 2008 LX 3.5L 1-2 Shift Improvements
· Cold (Transmission Fluid below 80° F) 2-3 Shift Improvements
Some customers may experience one or more of the concerns as follows:
· A MIL illumination for P0740 - Torque Converter Clutch Circuit/Open
· A DTC set active or stored for P1798 - Transmission Fluid Deteriorated

 

Works good, but I did blow a solenoid at 3000 miles. Other than that it's good.

 

"- Attempting to run in 3rd only by activating the "OD OFF" button does not function, trans will still try to force 4th/OD with button on. (not fun with a full load of people in hilly area)"

That's what I do. I flip the OD button on whenever I enter the hills and drive my 3-speed. Sounds like your OD momentary switch is not functioning correctly.

 

Does this only apply to 08 models?

I've been noticing issues with 2-3 upshifts when the trans is cold in my 07 that I don't recall having last winter

 

I looks to apply to selected 2007 & 2008 JK's;

http://project-jk.com/jeep-jk-tsb-re...smission-shift

 

Thanks! Hi Ho, Hi Ho, its to the dealer I go...

And I'll take a copy of that TSB with me

 

Let us know if it improves anything.

 

Matt08jk,

Did you get your tranny reprogrammed? Did you notice any change in performance?

Thanks,
D

 

I had my Auto Trans reprogrammed under TSB 21-001-08 REV. B for the Torque Converter Shudder and it seems to have helped.

I also had them flash the tires from the stock size (245/75/16) to the Rubi Size (255/75/17) and also noticed a difference in the shifting points of the transmission. Seems like I have more power now and I don't have to press as hard to accelerate when going up hills.