Ford Focus 2004 Owner's Manual page 112

Driving
If the vehicle begins to rotate
excessively left or right, spin out,
or slide sideways, the system will
attempt to correct the excessive
motion. If the vehicle does not
respond to steering inputs, the
system will attempt to alter the
turning response of the vehicle.
ESP does not work when the
vehicle is travelling backwards. In
reverse, the ABS and TCS systems
will continue to function.
Driving with TCS/ESP
BTCS/TCS indicator light
ESP indicator light
While driving, the indicator light
flashes during activation of the
system (excluding BTCS).
110
If the indicator light does not
illuminate when the ignition is
switched on or if it illuminates
continuously while driving, it
indicates a malfunction. During a
malfunction, the system switches
off. Have the system checked by an
expert.
Note: If the system is switched off
manually by pressing the Traction
Control System (TCS)/Electronic
Stability Program (ESP) switch,
the indicator light illuminates and
remains on until the system is
either switched back on or the
ignition is switched off.