The shift indicator, located in the console, displays the selected gear position. The body control module (BCM) controls the LEDs in the PRNDL display of the shift indicator through 4 control circuits. The parameters of the 4 control circuits to the shift indicator are bits A, B, C, and parity. These outputs are available for display on the scan tool. The BCM has 8 DTCs for these 4 control circuits. These DTCs diagnose a short or an open for each circuit. The BCM receives selected gear position information from the transmission control module (TCM) via serial data. The TCM receives the gear position through four inputs from the park/neutral position switch assembly.