Exhaust Brake Operation

4900 dm 10.04.003
  1. Before starting the engine, make sure that the exhaust brake is off. Wait until the engine has reached normal operating temperature before activating the exhaust brake.
  2. Warning: Do not use the exhaust brake when driving on slippery or low-traction road surfaces. Failure to follow this precaution could result in a loss of vehicle control and possible personal injury or property damage.

  3. When approaching a downhill grade, press the upper half of the exhaust brake switch to turn the exhaust brake on. When the exhaust brake is on, the status bar is illuminated.
  4. Remove your feet from the accelerator and clutch pedals.
  5. Notice: The exhaust brake is only active when engine speed is between 1100 and 2700 rpm.

    Note: Do not allow the engine to exceed its governed speed, or serious engine damage could result.

  6. While going down a grade, use a low enough gear to safely descend with a minimum application of the service brakes. As a general guideline, use the same gear as you would to ascend the hill.

    The following conditions should exist if the brake is operating properly:

    • A slight change in the sound of the engine may be noticeable.

    • Exhaust smoke should appear normal.

    • Engine temperature should remain in the normal operating range.

    • Road speed will usually decrease when the exhaust brake is applied during a descent. When the vehicle is carrying a heavy load or the grade is extremely steep, you may need to apply the service brakes occasionally.

    • The exhaust brake retards the vehicle with a smooth braking effect.

    • During a descent, the tachometer usually shows a drop in rpm, depending on the grade and the vehicle load.

    • Depending on the grade and vehicle load, the retarding force of the exhaust brake may be noticeable.

  7. Apply the service brakes to reduce engine rpm or make a slower descent by using a lower gear.
  8. Make sure the exhaust brake is turned off before shutting down the engine.
Note:
Document Number: 0000121911
Manual Publication Date: 2024-06-10
Topic Publication Date: 2024-06-10