Engine Brake

47x 13.03.000

Each engine manufacturer uses a specific engine brake for their engine. Refer to the engine manufacturer's operation manual for details of their particular engine brake product.

Regardless of the manufacturer, the engine brake is operated with the principles outlined in here.

Warning: To avoid injury from loss of vehicle control, do not activate the engine brake system under the following conditions:

on wet or slippery pavement, unless the vehicle is equipped with antilock braking system (ABS) and you have had prior experience driving under these conditions;
when driving without a trailer or pulling an empty trailer;
if the tractor drive wheels begin to lock, or there is fishtail motion after the engine brake is activated.

Note: When the engine brake is enabled, the engine brake lamp illuminates in the ICU. See Table..

Whenever vehicle braking is required on good road conditions, the engine brake may be used in conjunction with the service brakes. There is no time limit for operation of the engine brake. However, an engine brake does not provide the precise control of, and is not a substitute for, service brakes.

Warning: Usage of the engine brake as the primary braking system can cause unpredictable stopping distances, that could result in personal injury or property damage. Service brakes are the primary vehicle braking system.

Since the engine brake is most effective at rated engine speed, gear selection is very important. Gearing down the vehicle within the limits of the rated engine speed makes the engine brake more effective. Recommended engine braking speed is above 1800 rpm and below the rated speed.

"Control speed" is the speed at which the engine brake performs 100 percent of the required downhill braking, resulting in a constant speed of descent. The control speed varies, depending on vehicle weight and the downhill grade.

For faster descent, select a higher gear than that used for control speed. Service brakes must then be used intermittently to prevent engine overspeed and to maintain desired vehicle speed.

For slower descent, select a lower gear, being careful not to overspeed the engine. Occasional deactivation of the engine brake may be necessary to maintain the designated road speed under these conditions.

If the engine is equipped with both cruise control and an engine brake, the engine brake can operate automatically while cruise control is activated. The maximum amount of braking is selected with the engine brake control. When the vehicle returns to the set cruise speed, the engine brake will turn off.

The engine brake will only operate when the accelerator and clutch pedals are fully released.

ABS has the ability to turn the engine brake off if wheel slip is detected. The engine brake will automatically turn back on once wheel slip is no longer detected.

Engine Brake Operation

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

Note: Depending on the brake type, the engine brake may be disabled when engine temperature falls below a set level.

The engine brake control is located on the right-hand steering column lever. At the top position, the engine brake is off, and at the three lower positions, the engine brake is on and the intensity (low, medium, high) increases with each step down. See Fig..

Note: The cruise control system and safety systems may activate the engine brake regardless of the lever position.

Note: On vehicles equipped with a Detroit automated transmission, setting the engine brake with the cruise control set activates Deceleration Mode. Setting the cruise control while the engine brake is on activates Descent Control Mode. For information on these modes, see "Cruise Control" in General Information.

Off

Low

Medium

High

Fig. 1, Engine Brake Positions, Right-Hand Steering Column Lever

Table 1, Brake System Warnings, Indicators, and Messages

Brake System Warnings, Indicators, and Messages
Telltale	Color	Description		Driver Display
	Red	Low Brake Air Pressure (EPA10 and Newer)	Indicates air pressure in the primary or secondary reservoir has dropped below approximately 70 psi (483 kPa).
	Red	Low Air Pressure (EPA10 and Newer)	Alternate low brake air pressure telltale. Indicates air pressure in the primary or secondary reservoir has dropped below approximately 70 psi (483 kPa).
	Red	Parking Brake (EPA10 and Newer)	Indicates the parking brake is engaged.	N/A
	Amber	Vehicle ABS	Momentary illumination indicates the vehicle ABS is engaged. Solid illumination indicates a problem with the vehicle ABS. Repair the ABS immediately to ensure full braking capability.	N/A
	Amber	Trailer ABS	Momentary illumination indicates the trailer ABS is engaged. Solid illumination indicates a problem with the trailer ABS. Repair the ABS immediately to ensure full braking capability.	N/A
	Amber	Stability Event	Flashing indicates a stability event has been detected, and the ESC system is active. Solid illumination indicates a problem with the stability system. Repair the ESC system immediately to ensure full stability capability. For more information on the ESC system, see General Information.	N/A
	Amber	Wheel Spin Event	Flashing indicates a wheel spin event has been detected, and the ATC system is active.	N/A
		ATC Deactivated	Indicates the ATC SPIN button has been pressed to allow wheel slip.
	Green	Engine Brake	Indicates the engine brake is enabled.	N/A