Ford 2013 F-650 Owner's Manual page 163

162
The parking brake light illuminates and remains illuminated
P
(when the ignition is turned to the on position) until the
parking brake is released.
Releasing Spring Brake with Air Pressure
The air system in all vehicles with spring-actuated rear wheel parking
brakes is equipped with a tank valve located on the supply or service air
tank for connection to an outside air supply. The valve permits the
system to be recharged with air from an outside source, releasing the
spring-actuated parking brakes. The vehicle may then be towed in an
emergency.
An outside air source can be used only if the protected system is in
operating condition. If air pressure cannot be restored in the protected
air system, the spring-actuated brakes must be released manually.
Releasing Spring Manually
WARNING: Do not attempt to disassemble the parking brake
chamber under any circumstances. The high spring load may
cause serious injury if the chamber clamps are removed.
If air pressure is released from the spring brake chamber the power
spring applies the brake and, unless air pressure can be re-established,
the spring brake must be released as follows in order to move the
vehicle.
WARNING: Block the wheels to help prevent the vehicle from
moving.
WARNING: Unexpected and possibly sudden vehicle movement
may occur if these precautions are not taken.
2013 F-650/750 (f67)
Owners Guide gf, 2nd Printing, March 2013
USA (fus)
Brakes
Pull the yellow parking brake knob
out to apply the parking brake.
Push the knob in to release the
parking brake.