User's Manual

3
3. ANTILOCK BRAKE SYSTEM
(ABS) OPERATION
The Bendix
®
TABS‑6
™
Adv module uses wheel speed
sensors, modulator relay valve(MRV);and an ECUto
optimize the contact between the tires and the road surface
during a braking event where excessive wheel slip — or
wheel lock‑up — is detected.
When a situation is detected where the system needs to
intervene,theECUwillactivatetheMRVtoapplycontrolled
brake pressure at the wheel ends.
TheTABS-6AdvmoduleECUisabletomodulatethebrake
pressure with greater speed and accuracy than a driver.
Normal Braking
DuringnormalbrakingtheTABS-6Advmodulefunctions
as a standard relay valve.  If the ECU does not detect
excessive wheel slip, it will not activate the ABS system,
and the vehicle will stop with normal braking.
Axle Control
Axle control uses the modulator relay valve to control the
wheels at both ends of a given axle (or multiple axles in
cases where the MRV is controlling several axles).
In the case of braking surfaces with poor overall traction
(e.g. roads that are worn, slippery, or are made of loose
gravel) — or braking surfaces with areas of poor traction
(e.g. asphalt roads with patches of ice) — axle control ABS
interventions will maintain the wheel that is not slipping at
just under the speed that will lock the wheel. The system
permits the other wheel (that is experiencing slippage)
temporary periods of wheel‑lock during the intervention.
Axle control should not be used on 5th wheel dollies or
steerable axles.
When intervening on regular traction road surfaces, a
systemcongured foraxle controlperforms similarto a
side control, two‑modulator system.
ABS Fail‑Safe
The Bendix
®
TABS‑6
™
Adv module is designed to react
inafail-safemannerintheeventofasystemDiagnostic
TroubleCode(DTC).Forexample,iftheECUdetectsthat
asensorisnotresponding,anABSsystemDTCwillbe
set and the TABS‑6 Adv module will illuminate the trailer
ABS indicator lamp and revert to a fail‑safe mode where
some, or all, Advanced ABS functions (including TRSP)
maynotfunction.EvenincaseswheretheABSsystem
is completely disabled, the standard pneumatic brake
function of the vehicle will still be available, but without the
benetsofABS.TheTRSPfeatureisalsodisabledwithan
active ABS system diagnostic code. If the indicator lamp
is illuminated, always have the ABS system serviced at the
earliest opportunity.
3/4" NPT Supply
Port 1
Four 3/8" NPT Delivery
Ports 21
(To Brake Chambers)
3/8" NPT Control Port
with Integral Filter
3/8” NPT Load Port 42
for Air Suspension
(Plugged for Non-Air Suspension or Spring
Suspension Sensor Vehicles)
FIGURE 2 ‑ PORTS USED