DTC P0812: Transmission Range Switch ATPR Switch Circuit (Open): General Description

The transmission range switch is attached to a control shaft. Operating the shift lever makes the control shaft rotate via the shift cable. The A/T gear position indicator shows which position is selected according to the Low/High signal combinations, which vary based on the control shaft rotational angle. The control shaft changes the position of the transmission range switch, activates the manual valve, and switches hydraulic pressure to shift the transmission through forward/neutral/reverse. The transmission range switch signal is used to determine the shift schedule. The voltage is high (5 V or 12 V) at the powertrain control module (PCM) input terminal when each transmission range switch position signal is open, and it is low (0 V) when each switch is closed. If the R switch is open while driving the vehicle in R, the PCM detects a R switch open failure and stores a DTC.