2005 TSB#21-006-07 Full Disable Overdrive.

[HNicholl]

Since I purchased my 2005 CTD 3500 DRW I have been concerned that overdrive disable is not possible in the Tow/Haul Mode. In the recent issue of the TDR Magazine, Issue 58, Page 96 there is a reference to TSB #21-006-07 issued on 03/20/07. The description seems to imply that a software change would maintain the "normal" shift schedule when in the Tow/Haul mode with NO overdrive (4th gear). Currently the Tow/Haul engagement causes a change to a "Tow Haul mode" shift schedule which also allows 4th gear (overdrive gear) engagement. I called my dealer and they confirmed that this software upgrade is available.

Over the past 2 years I have read a considerable number of compliants regarding the dissatisfaction associated with the inability of locking out the overdrive (4th) gear in the 2005 Dodge Trucks. If this TSB was discussed on this forum previously I missed it. I feel that this TSB may be the answer to the wishes of many owners of 2005 vehicles.

My particular concern involves a desire to lock out overdrive while pulling my 14K 5th wheel trailer up long grades (at 60-70 MPG). Currently I have to wait for the transmission to automatically downshift from overdrive or manually intervene by further depressing the accelerator to force a downshift from the overdrive gear. Once in approximately 20 of these occurances (downshifting) I get a CEL (P1753) which puts the truck in a "limp mode" until I erase the code. This has only happened only during heavy towing. This problem is still present in spite of replacing the Transmission Valve Body and the motorized Throttle Valve Actuator.

It seems that giving up the "Tow/Haul" shift schedule to obtain a overdrive lockout would be a small price to pay for excessive downshifts which climbing long grades and may resolve the CEL (P1753) codes I occasionally experience. It may also make the use of my exhaust brake more effective.

Before I commit to this change, can any members correct my interpretation of the TSB or have any members applied this TSB to their 2005 CTD's and wish to comment on their satisfaction with the results.

Hugh