Operating the Brakes
Warning: Do not operate the vehicle with the front brakes backed off or disconnected. Backing off or disconnecting the front brakes will not improve vehicle handling and may lead to loss of vehicle control, resulting in property damage or personal injury.
Before driving the vehicle, secure all loose items in the vehicle so that they will not fly forward during a full brake application.
Notice: Do not continually press down on the parking brake control valve (yellow knob) without pressing down on the service brake pedal. This will damage the safety interlock.
The service brakes and parking brakes have a safety interlock that prevents the unintentional release of the parking brake. These instructions need to be followed for the appropriately equipped vehicle to release the parking brake interlock.
To ensure safe operation and minimum brake wear, follow the steps below when operating the brakes.
- When the ignition switch is turned on, the low air pressure
warning light (pressure circle icon) illuminates and the emergency
buzzer sounds.
- Monitor the air pressure system by observing the low air pressure warning light, the emergency buzzer, and both the primary and secondary air pressure gauges.
- The warning light and buzzer shut off when air pressure in both systems reaches 65 to 75 psi (448 to 517 kPa).
- Before driving the vehicle, continue to monitor the air pressure system until the air compressor has built up a minimum pressure of 95 psi (655 kPa) in both the primary and secondary air systems.
- While driving, the low air pressure warning light and buzzer
come on if air pressure drops below 65 to 75 psi (448 to 517 kPa)
in either system.
- If this happens, check the air system pressure gauges to determine which system has low air pressure.
- Although vehicle speed can be reduced using the service brake, either the front or rear service brakes will not be operating, causing a longer stopping distance.
- Bring the vehicle to a safe stop and have the air system repaired before continuing.
- During normal brake stops, depress the service brake until braking action slows down the vehicle. Increase or decrease the pressure on the pedal so that the vehicle comes to a smooth, safe stop.
- When the forward speed of the vehicle has decreased almost
to the idling speed of the engine, press in the clutch pedal (on manual
transmissions) and shift the transmission to neutral. Apply the parking
brakes, if the vehicle is to be parked.
Notice: Do not use the spring parking brakes if the service brakes are hot, such as after descending a steep grade. Also, do not use the spring parking brakes during freezing temperatures if the service brakes are wet. To do so could damage the brakes if hot, or cause them to freeze during cold weather.
If the brakes are wet, drive the vehicle in low gear and lightly apply the brakes to heat and dry them. Allow hot brakes to cool before using the spring parking brakes. Always chock the tires.
Important: In the event of a total loss of service brakes, use the parking brake control valve to bring the vehicle to a complete stop in the safest location possible.