9
ABS Indicator Lamp Operation (Bulb Check)
The ECU will illuminate the ABS Indicator Lamp for
approximately three seconds when ignition power is
applied, after which the lamp will extinguish if no diagnostic
trouble codes are detected.
The ECU will illuminate the ABS Indicator Lamp whenever
full ABS operation is not available due to a diagnostic
trouble code. In most cases, partial ABS is still available.
ATC/ESP Status/Indicator Lamp Operation
The ECU will illuminate the ATC/ESP lamp for approximately
2.5 seconds when ignition power is applied, after which the
lamp will extinguish, if no diagnostic trouble codes are
detected. The ECU will continuously illuminate the ATC/
ESP Indicator Lamp whenever ESP or ATC is disabled due
to a diagnostic trouble code.
During an ESP or ATC intervention, the lamp will flash
rapidly (2.5 times per second). When the ECU is placed
in the ATC Mud/Snow (off-road) mode, the lamp will flash
slowly at a rate of once every 2.5 seconds.
Trailer ABS Indicator Lamp Operation
The ECU will control the Trailer ABS Indicator Lamp
when a PLC signal (SAE J2497) from a trailer ABS ECU
is detected.
Hill Start Assist (HSA) Indicator Lamp Operation
Vehicles with HSA enabled, will illuminate the HSA Indicator
Lamp when ignition power is applied, after which the lamp
will extinguish if there are no issues with the HSA system.
ECU Configuration Test
Within two seconds of the application of ignition power, the
ECU will perform a test to detect system configuration with
regards to the number of wheel speed sensors and PMVs.
This can be audibly detected by a rapid cycling of the PMVs.
(Note: The ECU will not perform the configuration test when
wheel speed sensors show that the vehicle is in motion.)
Pressure Modulator Valve and Traction Control
Valve Chuff Test
Driver
Right Steer
Left Steer
Right
Additional
Left
Additional
Right Drive
Left Drive
FIGURE 9 -
vEHiCLE ORiEnTATiOn (TYPiCAL)
After the performance of the configuration test, the Bendix
®
EC-60
™
controller will perform a Bendix-patented PMV
and TCV Chuff Test. The Chuff Test is an electrical and
pneumatic PMV test that can assist maintenance personnel
in verifying proper PMV wiring and installation.
When ignition power is applied, each modulator solenoid
is briefly energized. If the air system is fully charged and
the service brake pedal is depressed during ignition, the
modulator creates a single, sharp audible “chuff” of air
pressure. The modulators are energized in a certain
pattern, as follows: right front, left front, right rear, left rear.
This test is performed only when the vehicle is stationary
(if the vehicle moves the chuff test will not be performed).
The Bendix EC-60 controller will perform a PMV chuff test
on all installed modulators in the following order:
• Steer Axle Right PMV
• Steer Axle Left PMV
• Drive Axle Right PMV
• Drive Axle Left PMV
• Additional Axle Right PMV
• Additional Axle Left PMV
• Drive Axle TCV
The pattern will then repeat itself.
If equipped with a Bendix EC-60 advanced controller,
following the completion of the second round of PMV &
TCV chuff tests, the controller (if configured to do so) will
perform a test to cross-check the trailer PMV operation with
the vehicle stop lamps. If the trailer PMV circuit is mis-wired
(including the steer axle TCV), the PMV will exhaust a large
amount of air, or none at all.
NOTICE:
If there are any active Diagnostic Trouble Codes,
the stop lamp cross-check portion of the chuff test will
not be carried out until all DTCs are fully diagnosed and
corresponding repairs are successfully conducted. The
ESP/ATC dash indicator will also be illuminated when there
are active ABS, ATC or ESP DTCs.
The ECU will not perform the PMV Chuff Test when wheel
speed sensors show that the vehicle is in motion.
ABS OPERATION
Bendix
®
ABS uses wheel speed sensors, ABS pressure
modulator valves, and an ECU to control either four or six
wheels of a vehicle. The Bendix EC-60 controller monitors
individual wheel turning motion during braking and adjusts
or modulates the brake pressure at the wheel end. When
excessive wheel slip, or wheel lock-up is detected, the
Bendix EC-60 controller will activate the pressure modulator
valves to automatically reduce the brake pressure at one
or more of the wheel ends. By these actions, the ABS
system helps to maintain the vehicle's lateral stability and
steerability during heavy brake applications and during
braking on slippery surfaces.
