Heavy Duty: Keeping Up With Modern ABS

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

“Some are just interested in the minimal ABS, because legislation requires it, therefore they’ve got to pay for it,” he says. “More people are at least trying to understand the auxiliary capabilities they can get—the ABS electronic control module can drive and manage other devices on the vehicle, so they’re looking at those as operational improvements.”

Another advantage of ABS is the use of telematics, says Matt Williams, manager of fleet sales, service and training with Troy, MI-based Meritor WABCO. Information gained can help fleets save on accident costs, providing both a safer option and a better return on investment.

“If you can prevent (an accident), that means the cargo’s going to get their safely,” he says. “It all depends on the fleet’s needs.”

Bendix electronic marketing manager Fred Andersky says fleets now want instant information on ABS interventions and issues.

“You’ll eventually reach a point where the service shop will get a message from the truck that indicates, say, a wheel speed sensor is acting up, and by the time the truck gets into that service shop, they’ve already got the wheel speed sensor, the fault code, they know what they need to get in there and do and they’re able to do it and get the driver back out on the road as quickly as possible,” he says.


Mark Hadley, director of fleet maintenance and property with the West Valley City, UT-based Central Refrigerated, has seen the evolution of ABS, and is glad his 1,850 Class-8 trucks have modern systems from Bendix.

“We make it mandatory that if an ABS light comes on, they get it fixed, because there is value in that ABS system,” he says. “You don’t see trucks any more that veer off and jackknife from a hard brake; they pretty much go straight down the road. The systems have been mostly flawless—very few codes, very few breakdowns related to that technology.”

Modern electronics, computers and software programs have made it much easier for technicians to troubleshoot ABS, but Hadley says even the best systems are not much use if the technicians don’t know how to maintain the systems.

“Obviously, they have to have the computer skills to be able to understand what the information is telling them,” he says. “On the technical side, they need to know how to download and interpret the data and follow the troubleshooting codes. They have simplified it enough; they have a troubleshooting tree to be able to tell you what the codes are telling you. That’s how you get your people trained. Just hook up the computer and it will walk you right through it, rather than try to troubleshoot and think you know it.”

In fact, Hadley says there is no such thing as too much training for his technicians, especially when there is a learning curve involved, as with modern electronics. He says going the extra mile to keep technicians up on the latest techniques and technology ends up being a big money-saver.

“When you’re as big as we are, manufacturers are offering training and we take advantage of all of it,” Hadley says. “Then it’s keeping it updated, (because) there’s always something new, and you have to make sure you have the latest enhancements. The technicians get paid for the time they spend on the equipment, so it’s important that they shorten their troubleshooting time by using that computer.”


Today’s ABS are by no means simple pieces of machinery. They generally include wheel speed sensing equipment, an electronic control unit (ECU), brake pressure modulator valves and a variety of electrical harnesses, switches, relays and lamps to interface with the vehicle power train, electrical and braking systems.

Sensors monitor wheel speed and relay information to the ECU, which sends signals to the modulator valve to provide the needed amount of brake pressure, determines if a wheel is about to lock up and activates the ABS valves, which regulate air pressure to the brake chambers, preventing a lock-up.

Despite all the gadgetry, Williams said the first step in properly troubleshooting and maintaining ABS is knowing basic electrical principles like ohms and voltage, and knowing how to use a voltmeter.

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