Heavy Duty: Keeping Up With Modern ABS

What your technicians need to know about troubleshooting today’s ABS.

Modern electronics and computers have dramatically cut the time it takes to troubleshoot ABS—meaning less “winging it” by your technicians—but properly maintaining the systems still seems to be another matter. Just ask Bob Blair.

The CEO of the Spokane, WA-based Lite-Check, Blair says a recent trip to a shop for a product demo convinced him some technicians still have no idea what they are doing with ABS.

“They had a trailer there where the ABS was not functioning, and they’d already spent three or four hours trying to figure it out and were at the point of replacing the ECU,” Blair says. “We plugged in the (diagnostic tool) and the first thing I did was to verify that the brake circuit and the auxiliary circuit were working, because that’s what powers the ECU. Well, when I hit the auxiliary circuit, the alarm came on—there was no power being delivered to the ECU. So the technician crawled under the front of the trailer and walked the auxiliary circuit back, and about 20 feet from the nose plug, there was an undone connection. He connected the circuit, the alarm went off, and we heard immediately the ‘click, click, click’ of the ECU.”


Unfortunately, lack of training and knowledge about ABS can end up costing the fleet far more than a new ECU. Last June, inspectors from the Commercial Vehicle Safety Alliance (CVSA) and Federal Motor Carrier Safety Administration fanned out across North America to perform 62,370 inspections on trucks and buses during Roadcheck 2007.

According to CVSA, brakes were the main issue, comprising 54 percent of total vehicle defects. A recent DOT study indicated brake problems were present at the time of a crash in nearly a third of all reported accidents.

Technicians should have had plenty of time to hone their ABS skills, as the National Highway Traffic Safety Administration (NHTSA) has for a decade required the systems on air-brake equipped truck-tractors, semi-trailers and single-unit trucks equipped with air brakes and hydraulically braked single-unit trucks over 10,000 pounds GVW.

Despite the occasional horror story from the shop, Rick Conklin, product manager with Elyria, OH-based Bendix Commercial Vehicles Systems, said many technicians have actually gone through a “pretty good” learning curve with ABS.

“The average technician out there is a lot smarter about electronic systems than five or 10 years ago,” Conklin says. “The end result is that a lot of the (problems of misdiagnoses) we saw with the first introduction of ABS and then with the mandate of ABS are really no longer problems. The parts changers have gotten word that that’s not necessarily the right thing to do, and that you do need to look into system level to be able to appropriately diagnose. And the service tools have gotten easier to use as well as the service documentation has gotten better and more clear for the technician to use on a daily basis.”

Duane Stocksdale, product manager—braking controls division with Kansas City, MO-based Haldex Brake Systems, says despite technician turnover that is creating problems for the industry, modern electronics have helped make their jobs easier.

“The ABS equipment and control modules have become more stable and there’s a lot more diagnostic tools out there,” Stocksdale says. “In the early days, everybody was trying to use blink codes and that made it more problematic, but now there’s more hand-held devices and a lot more use of PCs and diagnostic devices, where you have drop-down windows that lead you to the diagnostic area you need to take care of.”


They’re not free, but from keeping drivers and cargo safer on the road to using telematics to train drivers to avoid accidents, there are many reasons ABS is good for a fleet’s bottom line. The main thing fleets are looking for in ABS is reliability, says Stocksdale.

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