PORTLAND, Ore. – It started off as a simple letter; an update that school boards should check the Bendix-made anti-lock braking systems on Thomas Built school buses. With the warning of a potential safety threat on the first day of school, however, the technical defect became a media event.

By early September, Freightliner (which owns the Thomas Built nameplate) and International had announced plans to recall school buses with troublesome Electronic Control Units (ECUs) that can lead to a temporary loss of braking power at low speeds. Volvo, Freightliner and Sterling later announced plans to replace the equipment on trucks, before the recall was legislated.

The defect in question affects Bendix brakes built between March 1998 and this August, and can cause a vehicle to lose braking ability for up to three seconds when it is moving at less than 32 km-h. Although no accidents have been caused by the defect, Bendix reports 40 known incidents of drivers experiencing a short-term loss of stopping power.

Specifically, says Bendix spokesperson Julie Way, the problem involves the EC 17-1030R.

“There is also an installation issue which combines with that ECU to create the problem,” Way says. “When the wheel speed sensor is not fastened well enough, it chafes on the rotating components and sends a false wheel speed signal to the ECU, which reads it as a correct signal.” This causes the system to believe the wheels are locking up when they are not, and the anti-lock brakes begin their cycle. Way adds that the “incident rate” for this particular braking problem is a mere .012 per cent for all vehicles. She adds, however, that there have been five “minor” accidents involving straight trucks.

In all, 300,000 commercial trucks and buses are affected by the recall, and Bendix has increased the production of replacement components to 39,000 from 9,000 per month. Under an agreement with the U.S. National Highway Traffic Safety Administration, school buses must be fixed first, followed by straight trucks in critical applications such as refuse collection. Tractors and other straight trucks will follow.

Call 1-800-478-1793 or check out the Internet at www.bendix.com for more information. n