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 (D)

HI

LOW

LOW

HI

Intermediate (I)

LOW

LOW

LOW

LOW

Low (L)

LOW

HI

LOW

HI

HI = Ignition voltage

LOW = 0 volts