ISC, ISCe, QSC8.3, ISL, ISLe3, ISLe4 and QSL9 Engines – 020-999   Vehicle Braking – Overview

NOTE: The engine brake is comprised of two assemblies. The following instructions apply to both of the engine brake assemblies.

Engine brake controls consist of the following:

• An ON/OFF switch
• Clutch switch
• Throttle sensor
• Two-position selector switch (optional).

The throttle sensor is part of the accelerator pedal assembly located in the cab, and will deactivate the engine brakes when depressed.

The clutch switch uses the motion of the clutch linkage to deactivate the engine brakes when the clutch pedal is depressed. Depressing the clutch while in cruise control will disengage the cruise control.

The service brake switch is attached to the service brake.

Applying the service brakes while in cruise control will disengage the cruise control and enable the engine brakes.

NOTE: See the appropriate pages in this section for specific information about engine brake operation under certain road conditions.

To activate the engine brakes, switch the ON/OFF switch to the ON position. Once activated, the operation of the engine brakes is fully automatic.

WARNING  Do not use the engine brakes while bobtailing or pulling an empty trailer. With the engine brakes in operation, wheel lockup can occur more quickly when the service brakes are applied, especially on vehicles with single-drive axles.

Make sure the engine brakes are switched to the OFF position when bobtailing or pulling an empty trailer.

CAUTION  The engine harness are designed to assist the vehicle’s service brakes in slowing the vehicle to a stop.

Remember, service brakes will be required to bring the vehicle to a stop.

CAUTION  Do not operate the engine if the engine brakes will not deactivate.

If the engine brakes will not shut off, shut off the engine immediately.