Engine, A/T Controls - Hesitation On Acceleration/Harsh Shiftin: Overview
Classification: AT12-002BReference; ITB12-021B
Date: November 14, 2012
2011 - 2012 M37/M56; SHIFT RESPONSIVENESS ISSUES
This bulletin has been amended to add an addition vehicle into the APPLIED VEHICLES, change the first line of the IF Y0U CONFIRM statement and add additional part numbers to TABLE A. Discard any previous versions.
APPLIED VEHICLES AND VINS: 2011 - 2012 M56 (Y51) All
2011 M37 (Y51) All
2012 M37 (Y51) 2WD models: built before JN1BY1AP(*)CM 332915
2012 M37 (Y51) AWD models: built before JN1BY1AR(*)CM 393415
APPLIED DATES: 2012 M37 (Y51) 2WD models: built before August 1, 2011
2012 M37 (Y51) AWD models: built before July 31, 2011
IF YOU CONFIRM
That the customer has experienced or is experiencing:
^ Harsher than expected down shifts when coasting to a stop.
^ Hesitation/lag when accelerating after coasting.
^ Hesitation/lag or harsher than expected down shifts when coming to a stop and accelerating again (rolling stop).
^ Engine rev matching during moderate to heavy braking.
NOTE:
Engine rev matching is normal operation of the ASC (Adaptive Shift Control) in normal drive mode and sport mode. The ECM and TCM reprogramming in this bulletin will remove engine rev matching from ASC in normal drive mode, but it will remain as part of the ASC in sport mode.
ACTION
1. Refer to step 6 in the SERVICE PROCEDURE to confirm this bulletin applies to the vehicle you are working on.
2. If this bulletin applies, reprogram the ECM and TCM.
IMPORTANT:
The purpose of ACTION (above) is to give you a quick idea of the work you will be performing. You MUST closely follow the entire SERVICE PROCEDURE as it contains information that is essential to successfully completing this repair.
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