CITROËN C4 Handbook page 182

Driving
and possibly
flashing
Display of the message "Parking brake fault" and of the following
warning lamps:
and possibly
flashing
Battery fault:
180
Situations Consequences
To apply the electric parking brake:
F immobilise the vehicle and switch off the ignition.
F pull the control for at least 5 seconds or until application is complete.
F switch on the ignition and check the switching on of the electric parking
brake warning lamps.
The application is slower than during normal operation.
To release the electric parking brake:
F switch on the ignition.
F pull the control and hold it for approximately 3 seconds then release it.
If the braking warning lamp is flashing or if the warning lamps do not come
on with the ignition on, these procedures will not work. Place the vehicle
on level ground and have it checked by a CITROËN dealer or a qualified
workshop.
- Only the automatic application on switching off the engine and automatic
release on acceleration functions are available.
- The manual application/release of the electric parking brake and the
emergency braking are not available.
- If the battery warning lamp comes on you must stop immediately as soon as
the traffic allows. Stop and immobilise your vehicle (if necessary, place the
two chocks under the wheels).
- Apply the electric parking brake before switching off the engine.