Abs/Atc System (Anti-Lock Brakes); Abs Diagnostic - Monaco 2009 Knight Owner's Manual

ABS/ATc SYSTEM (ANTI-LOck BRAkES)

The motorhome is equipped with an anti-
lock braking system (ABS) and automatic
traction control system (ATC). The ABS
system monitors wheel rotation speeds by
using a 100-tooth magnetic tone ring mounted
to the hub. Revolving with the wheel, the
magnetic tone ring is polarized giving positive
and negative pulsations. A stationary sensor is
mounted adjacent to the tone ring to monitor
magnetic pulses. The pulses are monitored by
the ABS electronic control unit (ECU).
The ECU monitors all wheel sensors at
the rate of 100 times per second. The ECU
controls Pressure Modulator Valves. Pressure
Modulator Valves have two electric-over-air
solenoids, a hold solenoid and a release
solenoid. The modulator valves are open under
normal braking, allowing a straight through
air signal from the treadle valve to the brake
chamber. Should a wheel lose traction under
a braking application, the ECU will energize
the hold solenoid of the Pressure Modulator
Valve to interrupt the air signal from the
treadle valve to the brake chamber. The release
solenoid vents the existing air signal at the
brake chamber to the atmosphere, allowing
the skidding tire to regain traction. Skidding
tires have less tractive efficiency. It is possible,
under certain conditions, to have the wheel(s)
skid with a normal functioning ABS system.
The ABS itself does not apply additional
braking power. The purpose of the ABS is
to limit wheel lock and decrease stopping
distance. Cautious driving practices and
maintaining adequate safe distance when
following vehicles is the key to safe vehicle
operation.
WARNING
The ABS/ATC system is designed to
increase tire to road surface traction
but cannot overcome naturally
occurring laws of physics. The ABS/
ATC system, combined with safe
driving practices, will reduce the
possibility of wheel skid and loss of
lateral stability.
ABS Component Function:
Speed sensors and tone rings on each

wheel monitor wheel rotation.
Each speed sensor communicates wheel

rotation pulses to the Electronic Control
Unit.
The ECU receives the speed sensor

signal pulses to calculate speed and
acceleration rates of each wheel.
Based on the speed sensor input, the

ECU detects impending wheel lock
and operates the
ABS Modulator
Valves required
for proper
control. The
Modulator
Valves are
operated in the
Air, Release
or Hold modes
to regulate air
pressure to the
brake chambers.
Braking force is applied at a level

which minimizes the stopping distance
while maintaining as much lateral
stability as possible.
ABS Warning Light:
The ABS will perform a dash indicator lamp
check and self-diagnostic test each time the
ignition is switched to the on position.
When the ignition is turned on, the

ABS indicator illuminates momentarily
(3 seconds) verifying the self-
diagnostic test. If the ABS indicator
light remains on, or illuminates while
the motorhome is being operated,
this indicates a fault in the anti-lock
brake system. This fault will not
affect normal service braking. The
motorhome will need to go to a service
center to repair the problem.
INFORMATION
If a fault code occurs, call a Bendix
service locator at 1-800-247-2725 and
take the motorhome to the nearest
repair facility.

ABS Diagnostic

If the ABS light on the dash comes on it
indicates that a fault has occurred with the
Anti-lock Brake System only. Normal braking
is not affected but the motorhome will need to
go to a service center. The service center can
retrieve ABS diagnostic fault codes.
090307
209