Kia 2004.5 Spectra Service Technical Training page 179

2004.5 Spectra Technology
Brakes
The ABS adds the following to the Conventional Brake
System:
• A Mando MGH-20 integrated hydraulic and
electronic control unit (HECU) located in the right
front engine compartment
• A passive wheel speed sensor (WSS) at each wheel
• Two 30A fuses in the engine compartment junction
box
• An ABS indicator lamp on the IP
• Scan tool communication through the 16-pin under
dash connector.
The ABS/EBD system is designed to provide controlled
braking power in the longitudinal direction (forward
motion) of the vehicle to prevent wheel lock-up during
an emergency braking event. This allows the vehicle
to maintain maximum braking force, but prevents lock-
up of the wheels. This enables the driver to maintain
steering control during the emergency braking event.
ABS works by limiting the pressure to any wheel that
decelerates too rapidly and slips, allowing maximum
stopping force to be applied.
The ABS calculates the difference between the speed
of the vehicle and the wheel to determine the slip
rate. The slip rate is expressed as a percentage from
100% at wheel lock to 0% when the wheel rotates at
the same speed as the vehicle. Generally, slip in the
10-18% range (depending on conditions) is normal;
beyond this threshold, it's considered an ABS event.
In operation, the wheel speed sensors at each wheel
send signals to the HECU. If a wheel speed sensor
detects lockup (rapid deceleration) during brake
application, the HECU controls the hydraulic pressure
to that wheel cylinder.
9