A/T - Shift Stabilization Mode Explanation
Information IB05-05-S004Shift Stabilization Feature for Hydra-Matic 4L60-E
Transmission
ISSUE DATE: MARCH 2005
Affected Vehicles
2003-2005 Isuzu Ascender (US/UT)
Service Information
This bulletin contains information regarding Shift Stabilization mode. This feature affects transmission shift patterns and the customers perception of shift feel. Customers may notice a change in shift patterns between previously owned vehicles without shift stabilization and current vehicles with shift stabilization.
Shift Stabilization
Purpose
^ The purpose of shift stabilization is to reduce shift busyness during conditions that would otherwise produce frequent upshifts and downshifts, such as trailering, operating on grades or at higher altitudes.
^ Shift Stabilization is an algorithm in a vehicle's software/calibration that determines if and when to delay upshifts under load. Shift Stabilization only affects upshifts and not downshifts.
Activation
^ This feature is internal to the vehicle's software/calibration and requires no customer action to activate.
^ Shift Stabilization is effective in normal mode and cruise mode.
Function
^ Shift Stabilization calculates the required torque at the wheels in the current gear as well as the maximum torque available at the wheels in the next higher gear. If the torque in the higher gear is not sufficient, the transmission will remain in the current gear. If the torque in the higher gear is greater than or equal to the required torque, than the upshift is allowed.
^ High throttle opening will disable Shift Stabilization and normal downshifts will occur.
^ Shift Stabilization occurs in the 4L60-E for only 2-3 and 3-4 shifts.
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