Shift control system/method for vehicle equipped with driveline retarder

摘要

A control system and method is provided for controlling shifting of a vehicular powertrain system (10) including an internal combustion engine (12) drivingly coupled to a mechanical change-gear transmission (14) having a transmission output shaft (22) drivingly coupled to vehicular drive wheels (26) and having a driveline retarder (52) associated therewith. To prevent undesirable vehicle acceleration during shift transients occurring when the vehicle is traveling down a grade, input signals indicative of engine torque (TORQUEE) and vehicle acceleration (dOS/dt) are sensed and, if engine torque is negative (TORQUEE < REF1) and vehicle acceleration is positive (dOS/dt > REF2), the retarder is caused to apply an increased level of retarding torque to the vehicle drive wheels.