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)

HI

LOW

LOW

HI

Reverse (R)

HI

HI

LOW

LOW

Neutral (N)

LOW

HI

LOW

HI

Drive (D)

LOW

HI

HI

LOW

Intermediate (L4)

HI

HI

HI

HI

Low (L2)

HI

LOW

HI

LOW

HI = Ignition voltage

LOW = 0 volts