Circuit/System Description

WARNING: This page is about a different car, the 2018 GMC Yukon XL, 2018 GMC Yukon, 2018 Chevrolet Tahoe, 2018 Chevrolet Suburban 3500 HD, and 2018 Chevrolet Suburban. However, it is still accessible from the selected car via links, so may be relevant.

The driver shift request (DSR) allows the driver to select the desired range of gears for current driving conditions. The DSR shift system is activated when the gear selector is in the manual position. The DSR system is deactivated in all other range positions. Pressing the plus (+) switch once will command the body control module (BCM) to signal the transmission control module (TCM) to upshift to the next high gear. Pressing the minus (-) switch once will command the BCM to signal the TCM to downshift to the next lowest or previous gear. The TCM will not allow a downshift if the transmission is compromised by over-speeding. The automatic transmission manual shift switch is comprised of three different resistors values in series and two switches. The BCM supplies a 12 volt circuit to the automatic transmission manual shift switch. The signal circuit varies the voltage back to the body control module depending on which switch is depressed.