Ford F-650 2008 User Manual page 96

Driving
If the parking brake is applied due to low air pressure, immediate service
is required to the parking brake system.
Parking brake warning system
If the park brake light blinks and a chime sounds when pulling the yellow
control knob out, this indicates the parking brake is not functioning
properly; seek service for the parking brake immediately.
The light will blink and the chime will sound until the yellow control
knob is pushed in or approximately eight minutes have passed. If the
yellow control knob is pulled out again, the light will blink and the chime
will sound as a reminder that immediate service is required to the
parking brake system.
Releasing spring manually
Do not attempt to disassemble the parking brake chamber under
any circumstances. The high spring load may cause serious
injury.
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.
Block the wheels to help prevent the vehicle from moving.
Unexpected and possibly sudden vehicle movement may occur if
these precautions are not taken.
96
2008 F-650/750 (f67)
Supplement