Operating Instructions, On-Highway Transmissions
Allison automatic transmissions are electronically controlled. The shift selector provides five or six forward ranges and one reverse range.
P (Park, optional on 1000 and 2400 Series)
Use park when turning the engine on or off, to check vehicle accessories, to operate the engine in idle for longer than 5 minutes, and for stationary operation of the power takeoff, if equipped. This position places the transmission in neutral and engages the park pawl of the transmission.
Note: This does not apply the parking brake.
PB (Auto-Apply Parking Brake, optional on 2000 Series)
Warning: Before selecting PB on the shift lever, make sure the ignition switch is not in the OFF position. Selecting PB with the ignition switch in the OFF position places the transmission in neutral, but does not apply the parking brake automatically. The vehicle could roll unexpectedly, possibly causing property damage or personal injury.
The auto-apply parking brake places the transmission in neutral and applies the parking brake.
Note: Selecting PB on the shift lever does not engage the park pawl of the transmission.
R (Reverse)
Reverse is used to back the vehicle. When the selector is in reverse, the reverse warning signal will sound. Always bring the vehicle to a complete stop before shifting from a forward range to reverse, or from reverse to a forward range.
Notice: Extended idling in reverse may cause transmission overheating and damage.
Do not idle in reverse for more than 5 minutes. Select P (park), PB (auto-apply parking brake), or N (neutral) when time at idle exceeds 5 minutes.
Note: The shift into reverse may not succeed if a range inhibitor is active. Check for illumination of the RANGE INHIBIT indicator.
N (Neutral)
The neutral position places the transmission in neutral. This position is used when starting the engine and for stationary operation.
Warning: Failure to apply the vehicle parking brakes when the transmission is in neutral may allow the vehicle to move unexpectedly, possibly causing property damage or personal injury.
When neutral is selected, the vehicle service brakes, parking brake, or emergency brake must be applied. Selecting neutral does not apply vehicle brakes unless an auxiliary system to apply the parking brake is installed.
Warning: Do not coast in neutral. Coasting in neutral can cause an accident, possibly resulting in severe personal injury or death.
Do not let the vehicle coast in neutral. If the vehicle is allowed to coast in neutral, the engine brake will not work and you could lose control of the vehicle.
Notice: Coasting in neutral can cause severe transmission damage.
D (Drive)
Warning: When going downhill, use a combination of downshifting, braking, and other retarding devices to control vehicle speed and the engine's rated governed speed. Failure to do so could reduce vehicle braking, possibly causing loss of vehicle control and resulting in personal injury or property damage.
In the drive position, the transmission will initially go into first range when drive is selected. As vehicle speed increases, the transmission will upshift automatically through each available range up to fourth range or fifth range. As the vehicle slows, the transmission will downshift automatically.
When going downhill, downshift to a lower transmission range to increase engine braking and to help maintain control. The transmission has a feature to prevent automatic upshifting above the lower range selected. However, during downhill operation, the transmission may upshift to the next higher range, if the engine is exceeding its governed speed in the lower range.
Notice: Do not idle in drive for more than 5 minutes. Extended idling in drive may cause transmission overheating and damage. Always select PB (auto-apply parking brake) or P (park) if time at idle is longer than 5 minutes.
Note: The shift into drive may not succeed if a range inhibitor is active. Check for illumination of the RANGE INHIBIT indicator.
4 and 3 (Fourth and Third Ranges, optional)
Use the fourth or third range for city traffic and for braking on steep downgrades.
3 and 2 (Third and Second Ranges, standard)
Use the third or second range for heavy city traffic and for braking on steeper downgrades.
1 (First Range)
Use first range when pulling through mud or deep snow, when maneuvering in tight spaces, or when driving up or down very steep grades. First range provides the vehicle with its maximum driving torque and maximum engine braking effect.
Note: To have the transmission select these ranges automatically, leave the selector lever in D (drive).