PREVENTIVE MAINTENANCE BRAKE SYSTEM
Regional Haul
(R05/10) Y53-6033 – 187 –
be performed by a qualified technician at an Authorized
Service Center. The foundation brake system must be in
proper working order to ensure the best ABS perfor-
mance.
CAUTION: Do not weld anywhere on the vehi-
cle before detaching the ABS Electronic Con-
trol Unit (ECU) connector and all other
electronic control units. Welding equipment
can send an energy surge through electronic
equipment and cause damage. Disconnect all
ECUs before attaching welding equipment.
CAUTION: Never detach the ECU connector
with the ignition turned on. The connectors
could arc and damage electronic equipment.
Turn off the ignition before disconnecting any
electronic equipment.
Other precautions
• Check ABS wiring harnesses periodically for chafing
or other problems. No regular maintenance is
required on the ABS components.
• During wheel balancing, dyno testing, or any time the
ignition is on with part of the ABS disconnected, a fail-
ure code will be recorded. Consult with your Peterbilt
Dealer or Authorized Service Center for information
on clearing the failure code.
If, due to operating conditions, a brake application causes
either wheel on the same axle to begin skidding, wheel
speed sensors immediately signal the anti-lock controller
in the modulator assembly. The controller responds
instantly by signaling the solenoids in the modulator which
activate the air valves, reducing application pressure as
needed to prevent the wheels from locking up. If this over-
riding correction is effective, application pressure is
allowed to build up to the original input.
Any malfunction of the anti-lock system on one or more
axles will cause the system to fail-safe, and the panel-
mounted amber warning light will come on, indicating both
a malfunction, and automatic shut-down of the system. If
the foundation brake system is intact, the service brakes
will continue to function normally, but without benefit of
the anti-lock feature.
