How to maintain advanced safety systems and the wheel end components to help them perform at their best

In growing numbers, fleets are adopting advanced safety systems like full-stability and collision mitigation technologies, and equipping those same vehicles with air disc brakes to optimize performance and protect their safety investment.

This year, Bendix estimates between 39 and 42 percent of new Class 6 to 8 air-braked commercial vehicles will be built with stability systems, and between 16 and 19 percent will be built with a collision mitigation technology. Additionally, Bendix is forecasting that this year, 16 percent of Class 6 to 8 air-braked wheel ends will be equipped with air disc brakes.

Beginning in 2017, National Highway Traffic Safety Administration rules will require electronic stability control systems on most new Class 7 and 8 commercial vehicles.

As the technology advances, the maintenance of these safety and braking systems becomes that much more crucial in keeping vehicles operating and in safe working condition.

Electronic Issues

Bendix technical support teams regularly find that the first response to an electronics problem within an antilock braking system (ABS), or traction, stability  or collision mitigation technology, is to replace a component. Often, however, the issue is not the component, but a lower-cost problem that can be more difficult to detect.

Some simple troubleshooting can make the difference between an expensive repair with extended downtime and a quicker, cheaper solution. 

For instance, first responses to an electronic component issue should include examining the wiring and input sensors. Look for frayed wires, corroded connectors, blown fuses, out-of-position wheel speed sensors or a misaligned radar unit.

Other possible causes of issues that don’t require component replacement include a radar sensor that’s blocked by debris or snow, a damaged sensor bracket or J1939 network problems. Obvious damage, such as a crushed radar unit, would naturally require replacement of the part. There are no recommended maintenance practices for repairing the electronics within.

Physical Components

The physical components of a stability or collision mitigation system typically need attention only if certain aspects of the vehicle itself have changed. If the front end has been altered, for instance, or repairs have been conducted, such as front end alignments or steering linkage service, the steering angle sensor will need to be recalibrated according to manufacturer guidelines.

Changes in tire size necessitate updating the new tire values using diagnostic support software. Any repairs on the frame rail that call for removal or loosening of the yaw rate/lateral acceleration sensor will require recalibration of the sensor once it has been properly replaced and secured in the same position and orientation.

Next Diagnostic Level

If no visible reason for the problem is spotted, it’s time to step up to the next level of diagnostics: using your system’s supporting hardware and software. Time spent in pursuit of an accurate diagnosis isn’t wasted. You’ll save time and money in the long run.

Make sure you’re using the proper equipment and ensure that the software is up-to-date. Bendix ACom Diagnostic Software is one example of a free downloadable tool, and hardware such as Bendix Remote Diagnostic Units for both tractors and trailers are available from many aftermarket dealers to troubleshoot brake and safety systems.

Refer to the manufacturer’s Service Data Sheets for reference guides and instructions on reading information such as diagnostic unit blink codes.

Troubleshooting Steps

To properly assess the situation, refer to your stability or collision mitigation system’s troubleshooting instructions for specifics. Generally, they will follow these steps:

•  Run a Power-Up Self Test. On the Bendix Wingman Fusion system, for example, this means powering down the vehicle, putting the key in the “ignition power” position, toggling the cruise control and leaving it in the “on” position and then starting the vehicle, but not driving away. If the system finds an issue that will prevent it from functioning properly, it will create an audio alert and log a Diagnostic Trouble Code, depending on the manufacturer.

It is possible that while a Diagnostic Trouble Code may point to a specific component, it may be that the component is not getting power due to a worn wire or poor connection. As emphasized earlier, check these possibilities before replacing the component.

• Have a driver describe any system behavior that they believe indicates the technology is not working properly, and review the manufacturer-provided list of detailed scenarios and tests. These typically include yes or no questions about the performance of the vehicle’s cruise control, dashboard display icons, distance alerts and system interventions.

Wheel Ends

Fleets utilizing today’s advanced safety systems often spec air disc brakes to complement them and bring maximum value by helping vehicles shed speed safely, quickly and effectively. When it comes to the wheel ends and air disc brake upkeep, Bendix Spicer Foundation Brake – which combines and expands the complementary wheel end foundation brake technologies of Bendix Commercial Vehicle Systems and Dana Commercial Vehicle Products – recommends the following regular preventive maintenance:

• Checking caliper movement and mounting bolts, and ensuring the caliper slides freely.

• Measuring rotor thickness and looking for cracks beyond allowable limits.

• Inspecting pads for wear. Minimum allowable thickness is 2mm of friction material.

• Ensuring proper running clearances between the rotor and pads.

• Looking for evidence of damage, including corrosion, on tappets and boots. 

• Checking the mounting hardware of calipers and air chambers, and securing chamber mounting nuts.

Equipped together, air disc brakes, stability control and collision mitigation provide a highly effective and valuable vehicle safety package – and the right maintenance, done properly, protects fleets, drivers and everyone sharing the road.

Fred Andersky is the director of customer solutions for the Controls Group and director of government and industry affairs at Bendix Commercial Vehicle Systems (www.bendix.com). The company develops and supplies active safety technologies, energy management solutions and air brake charging and control systems and components under the Bendix brand name for medium and heavy duty trucks, tractors, trailers, buses and other commercial vehicles throughout. He has been involved with safety technologies at Bendix for more than 10 years and presents to government, industry and media about current and future technologies. Andersky holds a Class A CDL and often drives demonstrations of Bendix technologies.