Driver Assistance Systems,Safety Systems,Maintenance
How do you maintain an advanced driver assistance system on a tractor or truck? You probably wouldn’t believe how many times this question gets asked at shows, presentations, demos, or even media interviews. Even though many of these systems have been around for years, they’re relatively new in the long history of trucks (stability came on line in the 2004/2005 time frame), so the frequency of the question makes absolute sense.
One of the aspects that make advanced safety technologies different is that, unlike a number of systems on trucks, you don’t necessarily repair them. Typically, you update, adjust, or replace components in the safety system. Or – in the toughest cases – thread through miles of wiring harness to find that one wire with the worn insulation that is causing the fault! (This is not fun, trust me, but if you’ve got a bad wire and you just replace the component, you’ll still have a problem in the system and you’ve now spent money on a replacement that you didn’t need. Keep in mind, electronics tend to last, unless they get a power surge, submerged or damaged. Before you blame that component, check the connector and the wiring.)
Sorry for the side track, but I just couldn’t leave you hanging without a little electronics maintenance suggestion or two.
As you think of safety system maintenance, think of the approach to maintenance like a hierarchy (see figure 1), with higher level systems – like stability and collision mitigation – near the top, and the lower level systems – like tires and brakes – at the bottom (in this case being at the bottom means the foundation). In order for the higher level system to perform, the lower level systems need to be taken care of first.
Problems at the lower levels will impact the functionality at the higher levels. Following the hierarchy in Figure 1, a camera & radar-based collision mitigation technology (like the Bendix® Wingman® Fusion™ system) builds on the prior generation’s radar-based collision mitigation technology. Here, if the camera goes out, radar-based collision mitigation remains to support a driver. And if the radar goes out, the camera is intact for other functions such as lane departure warning, but not collision mitigation.
Along the same lines, the collision mitigation technologies build on the stability system. If the stability system has a fault, this will knock out the collision mitigation technology.
Following the chart, stability builds on ABS…so if ABS goes out, then stability and collision mitigation will as well. Keep in mind, however, that if ABS goes out, you still have braking…just without ABS. If the braking system is in disrepair, this will impact the ability of the other systems to perform at optimum levels.
The bottom line is that advanced safety technologies – like stability and collision mitigation – really rely on maintenance of lower level systems – like tires and the brakes – to ensure performance in the field. Think of it like this…if the tires are bald and the brakes are worn, when you need the collision mitigation system to intervene, what do you think happens? The system still intervenes like it should – the system sensors relay information to the electronic control unit (ECU), and the intelligence in the ECU takes that information and determines there is problem…a potential collision with the car in front of your vehicle. The ECU calls for an intervention – throttle is reduced, the engine retarder engages, and the brakes are called upon to engage…
I want you to hold that thought for a moment...remember, we’ve got worn brake pads and bald tires. Did you ever try to stop an 80,000 truck in an emergency situation under those conditions? Brake pedal to the floor, downshifting like crazy, brakes squealing, and that vehicle in front of you getting closer and closer and closer until…well, you know.
Now, think about the advanced safety system trying to do this…the system is delivering as much power as its capable of, but the resulting stopping distance – with bald tires and worn brakes – is likely going to be longer. That distance may be just a little longer than the actual space between the truck and the forward car. Again…you know. Bottom line is the lack of maintenance on the tires and brakes may impact the ability of the collision mitigation system to do its job effectively.
So where to start? Begin with the tires – make sure they are in good shape (proper inflation, proper wear, tread remaining, no wheel cracks, tight bolts) – so when the brakes apply, there is traction available to slow the vehicle. Then, check out your braking system. Is it in good shape? Are the air compressor and air dryer working properly? Do the brake shoes or disc pads have adequate material? Are the drums or rotors not cracked, damaged or otherwise in bad shape? Take care of these systems and the upper level systems will be ready to go. Of course, this doesn’t mean you don’t take care of diagnostic trouble codes or other issues with the advanced safety technologies. As noted earlier, these build on each other, so if you don’t address the lower level you can have an impact at the technologies above.
Which brings up a good point…don’t assume that because a particular system is out that this may be the source of the problem. Suppose the ABS system has a wheel-speed sensor fault. That might be taking down ABS. Because ABS is down, then stability is non-functional. With stability gone, so is collision mitigation technology. Starting at the bottom of the hierarchy can help you troubleshoot what appears to be an issue at the top.
Remember, bottom up, not top down, to start advanced safety system troubleshooting and maintenance. It can be the best route to success!
There’s a lot more to maintaining these systems than a single blog post can cover. Check out the other resources available to you at bendix.com and www.brake-school.com for more information and insight.
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