Circuit/System Description

WARNING: This page is about a different car, the 2015 Chevrolet Trax and 2015 Buick Encore. However, it is still accessible from the selected car via links, so may be relevant.

When the shift lever is placed in manual mode (M), the driver shift request , also known as the tap shift function is activated. The driver shift request allows the vehicle operator to shift gears by pushing the plus (+) button for an upshift or minus (-) button for a downshift. The body control module (BCM) supplies a signal circuit to the shift controller. The shift controller has switches connected to a resistor array. When the lever is in the M position, a voltage drop occurs across the resistor network. When the plus or minus button is pushed, a corresponding voltage drop occurs across the resistor network. This voltage drop is monitored by the BCM. The BCM will send the request to the transmission control module (TCM) to perform the upshift or downshift.

The TCM will not allow shifting to the next higher gear if the vehicle speed or engine RPM is too low. The transmission will not allow shifting to the next lower gear if the vehicle speed or engine RPM is too high.