Shift Selector

WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

Fig 1: Shift Selector

Courtesy of GENERAL MOTORS CORP.

The vehicle is equipped with a column type shift selector. In addition to the column shifter, another component associated with the shift selector is the park/neutral position (PNP) switch mounted on the selector shaft. The PNP switch transmits selector position information to the TCM. The PNP switch mounts directly onto the transmission housing, from the outside, and detects the angular position of the shift selector shaft. This position is communicated to the TCM so that certain vehicle control functions can be coordinated with the position of the shift controls. The PNP switch has redundant circuitry to alert the TCM in the event of a single wire or switch failure. The neutral signal output of the PNP switch is typically used as confirmation that the transmission is in NEUTRAL before the engine starter is engaged. The PNP switch is interfaced to the starter circuit with weatherproof electrical connectors. The reverse signal provision may be used to activate the vehicle back-up lights and/or reverse warning devices. The shift selector and PNP switch are customer supplied.

The operator chooses the transmission range by moving the selector lever to the appropriate gate position. When properly adjusted, the shifter gates prevent inadvertent shifting between ranges, and correspond to the internal transmission detent positions. A positive detent is provided in the transmission in order to maintain the selector shaft in the selected position.

The TCM shift calibration determines the available forward ranges for each selector position. Although specific installations vary, typical selector positions for the 1000 Series include the following:

P - PARK: The parking pawl is engaged. The transmission is in NEUTRAL. NEUTRAL is not available on all shift selectors. When available, it may be used when starting the engine and for stationary operations.
R - REVERSE: REVERSE is selected in order to move the vehicle backward.
N - NEUTRAL: NEUTRAL may be used when starting the engine and for stationary operations. The TCM disables the starter switch if a range other than NEUTRAL or PARK is selected before starting the vehicle.
D - DRIVE: DRIVE is the highest forward range used for normal driving. The transmission shifts to first range for starting, then automatically upshifts through the ranges, as operating conditions permit, until the highest range is attained.
4, 3, 2, 1 - Forward Range: There are four forward range selector positions. The first position after NEUTRAL is DRIVE, where all five forward ranges are available. Another position is FIRST range hold. There are three choices for the next two positions. These choices are 1-4, 1-3, and 1-2, which describe the ranges available in that position. The vehicle manufacturer chooses the two positions that best fit the vocation for which the vehicle is intended.