Selector Lever Position Indicator

Selector lever position indicator

PRND321:

Schematic:

On cars with automatic transmission, the selector lever position indicator shows which gear is selected by lighting up the corresponding gear symbol.

The selector lever indicator comprises 7 segments, each with its own light emitting diode beside the respective symbol (PRND321). The symbols are illuminated with additional light emitting diodes, the brightness of which is controlled by the rheostat value.

The light emitting diodes are powered by the main instrument unit and are grounded internally by the main instrument unit. TCM sends continuous bus information on the status of all the selector lever positions, unit ON/OFF.

Example
The following information is sent when the selector lever is in P position:

PARK Position Illumination:

The main instrument unit control module grounds the output to the P symbol LED, which then comes on while all the others remain off. If another selector lever position is selected, the status of the bus information will be changed, turning off the symbol that was on previously and turning on the symbol for the new selector lever position.

Diagnostics
The function has its own diagnostics in the sending system.