Bendix Commercial Vehicle Systems GEN 5 ABS User Manual
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FIGURE 3 - ABS Indicator Lamps
ABS Component Function
The ABS system operates as follows (see Figure 2).
1. Speed sensors on each wheel monitor wheel rotation.
2. Each speed sensor communicates wheel rotation pulses
to the central Electronic Control Unit (ECU).
3. The ECU receives speed sensor input, interprets the
signal pulses, and calculates speed and acceleration
rates for the wheels and the vehicle.
4. Based on speed sensor input with the brakes applied,
the ECU detects impending wheel lock and operates
the ABS modulator valves as required for proper control.
The modulator valves can be operated in either a release
or a hold mode to regulate air pressure in the brake
chambers.
5. Braking force is applied at a level which minimizes
stopping distance while maintaining as much lateral
stability as possible.
ABS Indicator Lamp
This lamp is the primary indicator of the ABS status.
•
The ABS lamp illuminates steadily for a two second
bulb-check whenever the switched ignition is ON. The
ABS lamp turns OFF after the bulb-check if there are
no ABS malfunctions present.
•
The ABS lamp flashes on and off continuously when
the off-highway mode is selected. (Special option for
military and off-highway vehicles.)
•
If the Indicator Lamp remains ON, after the bulb-check,
there is an ABS diagnostic trouble code that requires
service.
NOTE: In the case of a speed sensor failure which has
been corrected, the indicator lamp will remain on until
sensor output has been verified by the control unit. In this
case it is necessary to move the vehicle above 5 mph before
the indicator lamp will turn off.
ABS Trailer Indicator Lamp
Tractor/Towing vehicles manufactured on or after March 1,
2001 are equipped with a cab mounted “ABS Trailer”
indicator lamp.
When an ABS equipped trailer with Power Line Carrier
(PLC) communications capability is connected to the tractor,
the ABS Trailer indicator lamp will illuminate for a two second
bulb check after the ignition is switched on. The ABS lamp
turns OFF after the bulb-check if there are no ABS
malfunctions present on the trailer ABS.
If the trailer is NOT equipped with ABS or ABS with PLC
capability, the ABS trailer indicator lamp in the cab will not
illuminate.