GM Service Manual Online
For 1990-2009 cars only

If your vehicle is equipped with an automatic transmission, it features an electronic shift position indicator within the instrument panel cluster. This display must be powered anytime the shift lever is capable of being moved out of PARK (P). See Fuses and Circuit Breakers .

There are several different positions for your shift lever.

PARK (P): This position locks your rear wheels. It's the best position to use when you start your engine because your vehicle can't move easily. If your vehicle is equipped with the Allison® Transmission, use PARK (P) for stationary operation of the Power Takeoff (PTO), if equipped.

Caution: It is dangerous to get out of the vehicle if the shift lever is not fully in P (Park) with the parking brake firmly set. The vehicle can roll.

Do not leave the vehicle when the engine is running unless you have to. If you have left the engine running, the vehicle can move suddenly. You or others could be injured. To be sure the vehicle will not move, even when you are on fairly level ground, always set the parking brake and move the shift lever to P (Park). See Shifting Into Park . If you are pulling a trailer, see Towing a Trailer .

Caution: If you have four-wheel drive, your vehicle will be free to roll -- even if your shift lever is in PARK (P) -- if your transfer case is in NEUTRAL. So, be sure the transfer case is in a drive gear, two-wheel high (2H) or four-wheel high (4H) or four-wheel low (4L) -- not in NEUTRAL. See Shifting Into Park .

REVERSE (R): Use this gear to back up. If your vehicle is equipped with the Allison Transmission, the R may blink on the PRNDL if the shift inhibitor is active.

Notice: Shifting to R (Reverse) while the vehicle is moving forward could damage the transmission. The repairs would not be covered by the vehicle warranty. Shift to R (Reverse) only after the vehicle is stopped.

To rock your vehicle back and forth to get out of snow, ice or sand without damaging your transmission, see If Your Vehicle is Stuck in Sand, Mud, Ice, or Snow .

NEUTRAL (N): In this position, your engine doesn't connect with the wheels. To restart when you're already moving, use NEUTRAL (N) only. Also, use NEUTRAL (N) when your vehicle is being towed.

Caution: Shifting into a drive gear while the engine is running at high speed is dangerous. Unless your foot is firmly on the brake pedal, the vehicle could move very rapidly. You could lose control and hit people or objects. Do not shift into a drive gear while the engine is running at high speed.

Notice: Shifting out of P (Park) or N (Neutral) with the engine running at high speed may damage the transmission. The repairs would not be covered by the vehicle warranty. Be sure the engine is not running at high speed when shifting the vehicle.

DRIVE (D): This position is for normal driving. If you need more power for passing, and you're:

    • Going less than about 35 mph (55 km/h), push your accelerator pedal about halfway down.
    • Going about 35 mph (55 km/h) or more, push the accelerator all the way down.

You'll shift down to the next gear and have more power.

Drive (D) can be used when towing a trailer, carrying a heavy load, driving on steep hills or for off-road driving. You may want to shift the transmission to THIRD (3) or, if necessary, a lower gear selection if the transmission shifts too often.

Notice: Extended idling for more than five minutes in DRIVE (D) on vehicles equipped with the Allison Transmission may cause transmission overheating and damage. Always put the gearshift lever in PARK (P) if idle time is longer than five minutes.

If your vehicle is equipped with the Allison® Transmission, it will initially attain first range when DRIVE (D) is selected. As vehicle speed increases, the transmission will upshift automatically through each available range up to FIFTH (5). As the vehicle slows, the transmission will downshift automatically.

THIRD (3): This position is also used for normal driving, however it offers more power and lower fuel economy than DRIVE (D).

SECOND (2): This position gives you more power but lower fuel economy. You can use SECOND (2) on hills. It can help control your speed as you go down steep mountain roads, but then you would also want to use your brakes off and on. If you manually select SECOND (2) in a light duty automatic transmission, the transmission will drive in second gear. You may use this feature for reducing the speed of the rear wheels when you are trying to start your vehicle from a stop on slippery road surfaces.

FIRST (1): This position gives you even more power (but lower fuel economy) than SECOND (2). You can use it on very steep hills, or in deep snow or mud. If the selector lever is put in FIRST (1) while the vehicle is moving forward, the transmission won't shift into first gear until the vehicle is going slowly enough.

Notice: Spinning the tires or holding the vehicle in one place on a hill using only the accelerator pedal may damage the transmission. The repair will not be covered by the vehicle warranty. If you are stuck, do not spin the tires. When stopping on a hill, use the brakes to hold the vehicle in place.

On cold days, approximately 32°F (0°C) or colder, your transmission is designed to shift differently until the engine reaches normal operating temperature. This is intended to improve heater performance.

Tow/Haul Mode (Automatic Transmission)


Object Number: 865662  Size: B3

Your vehicle may be equipped with a Tow/Haul mode. The selector button is located on the end of the column shift lever. You can use this feature to assist when towing or hauling a heavy load. Turn Tow/Haul on and off by pressing the button until the Tow/Haul indicator light illuminates on the instrument panel. See "Tow/Haul Mode" under Towing a Trailer for more information.

Overdrive Disable (Allison Transmission)


Object Number: 865661  Size: B3

If your vehicle has an Allison Transmission you may have the overdrive disable feature. The overdrive disable feature prevents the transmission from shifting into fifth (5) gear. The selector button is located on the end of the column shift lever. You can turn overdrive disable on and off by pressing and holding the button at the end of the column shift lever until the indicator light, on the instrument panel, illuminates.

If your vehicle has both Tow/Haul and overdrive disable tap the button once to enable or disable Tow/Haul, and press and hold the button to enable or disable overdrive disable.