GM Service Manual Online
For 1990-2009 cars only

Transmission Range Switch Logic

Gear Selector Position

Signal A

Signal B

Signal C

Signal P

Park (P)

LOW

HI

HI

LOW

Reverse (R)

LOW

LOW

HI

HI

Neutral (N)

HI

LOW

HI

LOW

Drive 3 (3)

LOW

LOW

LOW

LOW

Drive 2 (2)

LOW

HI

LOW

HI

Drive 1 (1)

HI

HI

LOW

LOW

HI = Ignition voltage

LOW = 0 volts