Circuit Description

WARNING: This page is about a different car, the 2003 Oldsmobile Bravada, 2003 GMC Envoy XL, 2003 GMC Envoy, and 2003 Chevrolet TrailBlazer. However, it is still accessible from the selected car via links, so may be relevant.

The transmission range (TR) switch is part of the park/neutral position and back-up lamp switch assembly and is externally mounted on the transmission manual shaft. The TR switch is a multi-signal switch. The PCM supplies ignition voltage to the TR switch on four signal circuits, A, B, C, and P. Each gear selector lever position grounds one or more of the switch circuits. In order to determine the gear range selected by the driver, the PCM compares the voltage combinations on the signal circuits to a look up table stored in the PCM memory. PCM detects the selected gear range by the state change of the switch input. Refer to Transmission Range Switch Logic table.

Switch input to the PCM is represented on the scan tool as HI and Low. HI indicates an ignition voltage signal. Low indicates a zero voltage signal. The four parameters represent transmission range switch signal A, B, C and Parity.

DTC P0706 will set if the PCM detects start-up in a drive range or vehicle speed in the PARK or NEUTRAL range. DTC P0706 is a type C DTC.