Bendix Commercial Vehicle Systems TABS-6 ADVANCED MC SD SHEET - Manual (Page 8)

8
cAution: correct wheel speed sensor installation is
necessary for optimal AbS operation.
NOTE: If the trailer is equipped with a lift axle that will use
wheel speed sensors, it is important that secondary sensors
SE and SF be used for this axle. See the system diagrams
included in this document. In all cases, the primary wheel
speed sensors must be located on the fixed axle. For
2S/2M systems, the fixed axle sensors are SC and SD.
1. For increased corrosion protection Bendix recommends
that a high‑temperature rated silicon‑ or lithium‑based
grease be applied to the interior of the mounting block,
the sensor, and to a new clamping sleeve.
2. Install the new clamping sleeve fully into the block,
with the retaining tabs toward the inside of the vehicle.
Please note that Bendix WS‑24 wheel speed sensors
must use the correct clamping sleeve to avoid problems
associated with reduced retention force, such as sensor
movement and resulting ABS trouble codes. see
Figure 4.
3. Gently push (DO NOT STRIKE) the sensor into the
mounting block hole until it bottoms out on the face of
the tone ring. Secure the cable lead wire to the knuckle/
axle housing 3-6 inches from the sensor.
4. Apply a moderate amount of dielectric non‑conductive
grease to both the sensor and harness connectors.
5. Engage the connectors, and push them together until
the lock tab snaps into place. It is permissible to use an
extra wire retainer (part number 300122, or equivalent),
if available, to hold the connectors together.
The friction fit allows the WS-24 sensor to slide back and
forth under force, but to retain its position when the force
is removed. When the WS‑24 sensor is inserted all the
way into the mounting block and the wheel is installed on
the axle, the hub exciter contacts the sensor, which pushes
the sensor back. Also, normal bearing play will “bump” the
sensor away from the exciter. The combination of these
two actions will establish a running clearance, or air gap,
between the sensor and exciter.
cAution: Wheel bearing maintenance is an important
part of keeping the wheel speed sensors in the correct
position. excessive wheel end play can result in dtcs
in cases where the sensor is pushed too far away
from the tone ring for a good signal to be produced.
maintain wheel bearings per the manufacturer's
recommendations.
8. ABS INDICATOR LAMP
Trailer‑mounted Lamp
The Bendix
® TABS‑6 ™ Adv MC module controls an ABS
indicator lamp to show the trailer ABS status. With power
supplied by the towing vehicle — if there is an active
Diagnostic Trouble Code (DTC), or during the bulb test at
start‑up — the module illuminates the ABS indicator lamp
by providing a 12.0 VDC signal. (The other side of the
lamp is grounded.) The ABS indicator lamp output uses
pin 5 of the 7‑pin connector on the module.
Dash‑mounted Lamp (PLC Controlled)
TABS-6 Adv MC modules use SAE J2497 standards to
support Power Line Carrier (PLC) communication. The
status of the trailer ABS is transmitted over the ignition
power wire (the blue wire of the J560 connector) — pin 1
of the 7‑pin module connector.
If there is an active DTC, during the bulb check at start-up,
the TABS‑6 Adv MC module will transmit a signal over
the power line to the towing vehicle’s ECU. The towing
vehicle’s ABS controller will then illuminate the trailer ABS
indicator lamp mounted on the dash.
9. BENDIX ® WS‑24 ™ WHEEL
SPEED SENSORS
see Figure 4. Wheel speed data is provided to the TABS‑6
Adv MC module by the Bendix ® WS‑24 ™ wheel speed
sensors. Typically, the WS‑24 wheel speed sensor is
installed in a mounting block that is welded to the axle
housing. The WS‑24 wheel speed sensors are protected
by a stainless steel sheath. They are designed to be
used with beryllium copper clamping sleeves (sometimes
referred to as a “retainer bushing”, “friction sleeve”, or “clip”)
(see Figure 4). The clamping sleeve provides a friction fit
between the mounting block bore and the WS‑24 sensor.
Vehicles have an exciter ring (or “tone ring”) as part
of the wheel assembly. (The default setting expects a
100-tooth tone ring to be used. see section 17 for more
information.) As the wheel turns, the teeth of the exciter
ring pass the wheel speed sensor, generating an AC signal
which is delivered to the TABS-6 Adv MC module ECU.
The signal varies in voltage and frequency as the wheel
speed changes.
Vehicle axle and ABS control configurations determine
if two, or four, wheel speed sensors are required. see
Figures 20 and 21 for an electrical system schematic
showing wheel speed sensor connector pin locations.