GM Service Manual Online
For 1990-2009 cars only

Gear Selector Position

Signal A

Signal B

Signal C

Signal P

Park

LOW

HI

HI

LOW

Park/Reverse

LOW

LOW

HI

LOW

Reverse

LOW

LOW

HI

HI

Reverse/Neutral

HI

LOW

HI

HI

Neutral

HI

LOW

HI

LOW

Neutral/Drive 6

HI

LOW

LOW

LOW

Drive 6

HI

LOW

LOW

HI

Drive 6/Drive 4

LOW

LOW

LOW

HI

Drive 4

LOW

LOW

LOW

LOW

Drive 4/Drive 3

LOW

HI

LOW

LOW

Drive 3

LOW

HI

LOW

HI

Drive 3/Drive 2

HI

HI

LOW

HI

Drive 2

HI

HI

LOW

LOW

Open

HI

HI

HI

HI

Invalid

HI

HI

HI

LOW

Invalid

LOW

HI

HI

HI

HI = Ignition voltage

LOW = 0 volts