Gear Position Switch
The gear position switch output signals are related to the position of the gear selector lever assembly. The switch is installed on the selector shaft on the left side of the automatic transmission. Slotted mounting holes allow the switch to be turned relative to the shaft for adjustment. A lead connects the switch to the vehicle wiring.
Movement of the gear selector lever assembly turns the selector shaft, which connects with 3 sliding contacts in the switch. The contacts are identified as X, Y and Z. When closed:
- The X, Y and Z contacts output a combination of ground signals to the auto gear box control unit as shown. See Fig 1.
- The outputs of the X, Y and Z contacts are monitored by the auto gear box control unit, ECM and the BECM to determine the position of the gear selector lever assembly.
The signals are interpreted by the auto gear box control unit for the correct gear selection. The ECM uses the signals to control engine idle speed etc. The BECM uses the signals to illuminate the gear selection display on the selector cover, operate the reverse lamps, wiper reverse operation and message center display etc.