GM Service Manual Online
For 1990-2009 cars only

Transmission Internal Mode Switch Logic

Gear Selector Position

A

B

C

P

Park

LOW

HI

HI

LOW

Park/Reverse

LOW

HI

HI

HI

Reverse

LOW

LOW

HI

HI

Reverse/Neutral

HI

LOW

HI

HI

Neutral

HI

LOW

HI

LOW

Neutral/Drive 5

HI

LOW

LOW

LOW

Drive 5

HI

LOW

LOW

HI

Drive 5/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

    • HI = Ignition voltage
    • LOW = 0 voltage