Circuit/System Description

A redundant set of manual mode UP/Down switches are located on the steering wheel horizontal crossbar facing the instrument panel. The plus (+) switch is located on the right side of the steering wheel and the minus (-) switch is located on the left side of the steering wheel. A 12 volt parallel signal circuit from the body control module (BCM) supplies voltage to the automatic transmission manual shift switches on the steering wheel. Up shifts or down shifts are accomplished by pushing rearward on the up shift plus (+) switch or rearward on the down shift minus (-) switch. When either the Up shift or Down shift is operated, this creates a voltage drop on the signal circuit to the BCM. The BCM interprets this signal and sends the Up or Down shift command out on the serial data line to the transmission control module (TCM) and to the engine control module (ECM) to perform the requested shift.