BW8207 Bendix Global Scalable Brake Control (GSBC) System Operator’s Manual 28
BENDIX GSBC SYSTEM TROUBLESHOOTING CONT.
PRESSURE PLAUSIBILITY TESTS
In normal operation, the Bendix® GSBC® system uses electronic control signals to
control the amount of brake pressure that is delivered to the foundation brakes. To
ensure functionality in the event of an electrical failure, the brake system still sends
and receives pneumatic signals using the foot brake valve, EPMs, and eTPCM.
To check and conrm the operation of this pneumatic backup control system, the
GSBC system will occasionally disable the electronic control system and monitor the
operation of the pneumatic valves and air lines by running the Temporary Backup
Mode Test (refer to page 29) and the Reverse (Validation) Test (refer to page 34).
If the correct preconditions are met, the tests will run automatically and without
driver notication to conrm the operation of the underlying pneumatic and
mechanical parts of the system. These tests ensure that high-severity failures in air
lines or control valves can be caught quickly so that the driver can be notied and
the problem corrected.
The driver will be prompted by the dashboard display ONLY IF the system does NOT
get the opportunity to run these tests automatically.
Faults and Potential Causes
Pressure Plausibility Tests are safety monitoring functions to ensure that the
mechanical components of the brake system are operating correctly. If the test is
not run, a yellow warning lamp may be set on the dashboard, accompanied by a
warning pop-up on the dashboard when the vehicle is started.
If a test runs and fails, it can result in a red or yellow EBS warning lamp on the
dashboard. These failed tests are usually indicative of a problem that has been
detected with the braking system like a signicant air leak, or a blocked or kinked
air line.
If either the Temporary Backup Mode Test or the Reverse (Validation) Test fail,
the vehicle should be inspected by a qualied technician. While the Reverse Test
may clear some faults set within the system by these tests, it will not correct
mechanical problems with the vehicle.
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