If your vehicle is has 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 moved out of PARK (P). See Fuses and Circuit Breakers .

There are several different positions for your shift lever.

Automatic Transmission

Allison Transmission®

See "Range Selection Mode" later in this section.

PARK (P): This position locks your rear wheels. It is the best position to use when you start your engine because your vehicle cannot move easily. If your vehicle has the Allison Transmission®, with the Power Takeoff (PTO), use PARK (P) when starting. The Allison Transmission® has a park pawl that is designed to hold the weight of commercial medium duty trucks. Therefore, the Allison Transmission® uses larger parts than other automatic transmissions. These larger parts may sometimes make a clunk noise when the selector lever is moved from DRIVE (D) or REVERSE (R) to PARK (P). This is normal and there is no damage occurring during these shifts. When parked on a hill, especially when loaded, you may notice an increase in the effort to shift out of Park. See Torque Lock (Automatic Transmission) under Shifting Into Park for more information.

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 has the Allison Transmission®, the R on the shift display, may blink 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 does not connect with the wheels. To restart when you are 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 are:

By doing this, the vehicle shifts down to the next gear and has 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.

If your vehicle has the Allison Transmission®, it will shift into first range when DRIVE (D) is selected. As vehicle speed increases, the transmission will upshift automatically through each available range up to SIXTH (6). As the vehicle slows, the transmission will downshift automatically.

The Allison Transmission® uses a shift stabilization feature that adjusts the transmission shifting to the current driving conditions in order to reduce rapid upshifts and downshifts. This shift stabilization feature is designed to determine before making an upshift if the engine will be able to maintain vehicle speed by analyzing things such as throttle position, vehicle load, and hill grade. If the shift stabilization feature determines that current vehicle speed cannot be maintained, the transmission does not upshift and instead holds the current gear. In some cases, this may appear to be a delayed shift, however the transmission is operating normally.

The Allison Transmission® also uses adaptive shift controls. Adaptive shift controls continually compares key shift parameters to pre-programmed ideal shift conditions. The Allison Transmission® constantly makes adjustments to improve vehicle performance according to the way the vehicle is being used, such as with a heavy load. During this adaptive shift controls process, some shifts may feel different as the transmission determines optimum settings for a particular shift.

MANUAL MODE (M): This position, is available on vehicles with the Allison Transmission®. It lets drivers select the range of gears appropriate for current driving conditions. If your vehicle has this feature, see Range Select Mode (Allison Transmission®) later in this section.

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 an automatic transmission, the transmission will start 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 shift lever is put in FIRST (1) while the vehicle is moving forward, the transmission will not 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.

Range Selection Mode (Allison Transmission®)

If your truck has an Allison Transmission® your vehicle is equipped with a Range Selection System.

To use this feature, do the following:

1. Move the shift lever to the MANUAL MODE (M). When in the MANUAL MODE, the transmission's current gear range will be the highest attainable range with all the lower gears available.
2. Press the plus/minus buttons to select the desired range of gears for your current driving conditions.

The Range Selection Mode allows you to control the engine and vehicle speed while driving down hill by allowing you to select a desired gear.

The DIC shows the six available ranges with the highest attainable range shown in brackets. See Driver Information Center (DIC) and DIC Operation and Displays for more information.

While using the Range Selection mode feature, cruise control and the Tow/Haul mode can be used.

Low Traction Mode (Allison Transmission®)

If your vehicle has the DURAMAX® diesel engine and the Allison Transmission®, it is equipped with a Low Traction Mode that assists in vehicle acceleration when road conditions are slippery, such as ice or snow. While at a stop, selecting the second gear range using the Range Selection system, will allow the Allison Transmission® to limit torque to the wheels after it detects wheel slip, preventing the tires from spinning.

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.

Cold Weather Operation (Allison Transmission®)

On cold days, approximately 32°F (0°C) or colder, your automatic transmission is designed to shift differently. The transmission uses a warm-up mode shift schedule until the engine reaches normal operating temperature. While the transmission is in warm-up mode it is normal for transmission upshifts to be delayed or held longer. This feature improves heater performance by giving quicker vehicle warm-ups.

When temperatures are below -13°F (-25°C), the transmission will prevent certain operations to protect against damage. When active the DIC will display the message "Trans in Warm-up".

See DIC Warnings and Messages for more information.