GM Service Manual Online
For 1990-2009 cars only

Gear Selector Position

Signal A

Signal B

Signal C

Signal P

Park (P)

HI

LOW

LOW

HI

Reverse (R)

HI

HI

LOW

LOW

Neutral (N)

LOW

HI

LOW

HI

Drive 4 (OD)

LOW

HI

HI

LOW

Drive 3 (3)

HI

HI

HI

HI

Drive 2 (2)

HI

LOW

HI

LOW

Drive 1 (1)

LOW

LOW

HI

HI

HI = Ignition voltage

LOW = 0 volts