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California Highway Patrol Info Bulletin 11-15-00 - Transporation (CA Dept of Education) DEPARTMENT OF CALIFORNIA HIGHWAY PATROL
November 15, 2000
AIR BRAKE SAFETY RECALL Vehicle manufacturers and Bendix Commercial Vehicle Systems have become aware of reported
incidents of unwanted temporary antilock brake system (ABS) activation at low speeds, on certain
air brake-equipped vehicles. The issue can arise on school buses, buses and trucks equipped with
an electronic control unit (ECU) with the model number EC-17-1030R, in combination with
certain installation or equipment issues that can generate a type of erratic false wheel speed signal
to the ECU. The defect can cause the driver to lose the ability to brake for as long as four seconds
at speeds below 20 miles per hour. Full braking is restored after a few seconds of ABS activity.
The installation issue that can cause this defect is a chafed wheel speed sensor wire rubbing on
a rotating component resulting in an unintended signal being sent to the ECU to release the
brakes for several seconds instead of activating the brakes. The equipment issue that can cause
this same problem is a displaced or loose sensor exciter ring (tone ring).
For there to be a risk of unwanted ASS activation, vehicles must have both an ECU model EC-1-
7-103OR and one of the installation or equipment defects. Bendix has stated that "If a driver
senses a loss of brakes and cannot stop the vehicle, he or she can apply the parking brakes to stop
the vehicle." Drivers of buses without anti-compounding systems can apply the parking brake by
pulling the yellow dash button out, with anti-compounding systems, drivers should be reminded to
remove their foot from the brake pedal first, then pull the yellow dash button out. Most buses and
school buses are equipped with anti-compounding.
Bendix, the vehicle manufacturers, and the National Highway Traffic Safety Administration
(NHTSA) are recommending that all vehicles affected by this recall be inspected for wheel speed
sensor cable abrasion or chaffing and for tone ring issues via ABS diagnostics light-emitting
diode or diagnostic tools and are not recommending that buses or trucks be taken out of service.
The recall affects over 300,000 vehicles
- 1 including 46,000 buses and school buses. The NHTSA has determined that school buses and
fire and emergency service vehicles would be the first priorities for this recall.
Bendix has already taken steps to maximize production capacity in order to manufacture the
required number of ECUs for the recall. In the meantime, there are some steps owners of affected
vehicles can take to reduce the chances that a problem will develop:

Inspect the vehicle for damaged speed sensor wires. Verify that the wires have not been

damaged from rubbing or chafing on any moving parts, and make sure the wires have not

been pinched by the axle stops, cross-members, brackets, etc. If a damaged sensor wire is

found, contact the local dealer and have the speed sensor wire replaced.
To prevent speed sensor wire damage, look for excessive wire length at the wheel ends and
near the drive shaft. If there is extra wire length at the wheel end, make sure the wires can not
rub on the tire, rim, brake drum, or brake rotor disc. Also, consider whether or not the wires
can come in contact with any moving parts as the vehicle is making a full turn in either
direction. Wires should be at least 1.5 inches away from all rotating parts.

If the ABS dash lamp comes on at any time (even if only momentarily), except

during engine start-up, a diagnostic check should be performed
A visual inspection of the tone ring is performed by removing the tire, wheel and drum.
Inspect the tone ring for proper seating on the hub flange. There should be an even gap at the
seat and tone ring as the hub is rotated. If the tone ring is machined or cast into the hub
surface, only inspect for surface damage. After inspection, ensure that the wheel speed sensor
is pushed all the way into the sensor mounting block, making sure that it contacts the tone
ring, setting the proper gap.
Bendix recommends that service personnel refer to the vehicle manufacturer's
published inspection procedures for the specific vehicle. Any unwanted ASS activation or brake
performance issues should be reported to the vehicle manufacturer or dealer. Once owners receive
the vehicle recall notice, they should plan to have the ECU changed out promptly. This recall
affects only air-braked vehicles, not hydraulic-braked vehicles.
- 2 ­
Additional Information regarding this safety recall may be obtained from Bendix and the
following vehicle manufacturers:
Bendix Commercial Vehicle Systems Amtran
1-800-478-1793 Corporation
1-501-327-7761 Blue Bird Body Company, Inc.
1-912-757-7100 Freightliner LLC
1-800-547-0712 International Truck and Engine Corporation
1-800-448-7825 Thomas Built Buses, Inc.
1-336-889-4871

1-800-541-6535
Volvo Trucks North America, Inc.
Any questions regarding this Information Bulletin should be directed to Commercial Vehicle
Section at (916) 445-1865.
ENFORCEMENT SERVICES DIVISION
OPI: 062
DISTRIBUTION: 3A E S(Holders of HPG 83.2, Motor Carrier Advisory Committee (MCAC),
Motor Carrier Interested Parties (MCIP), Alternative Fuels Interested Parties (AFIP), Bus Fleet
Operators (BFO), and School Bus Mailing Lists)
- 3 ­