On-board vehicle diagnostic loses its wires

Jan. 1, 2020
The history of automotive on-board diagnostics begins with California emissions regulations of the 1980s. For the first time, cars were required to warn the driver if an emissions control device failed. While those warning systems met the law, it qui

OBDIII is on the way, offering a new means to communicate with and diagnose vehicles.

The history of automotive on-board diagnostics begins with California emissions regulations of the 1980s. For the first time, cars were required to warn the driver if an emissions control device failed. While those warning systems met the law, it quickly became apparent that they weren't accomplishing the real goal of the California Air Resources Board (CARB).

The system that became known as on-board diagnostics one (OBDI) could turn on a "Check Engine" light if something failed, but it offered little help to repair technicians. In those days, diagnostic tools, as well as most technicians' diagnostic skills, were rudimentary at best, because closed-loop fuel and position sensors had never been used on production engines before. While some techs learned how to find the root cause of the failure, all too often a tech simply replaced whatever part the OBD system said had failed, hoping the "Check Engine" light would go out. Even CARB realized this didn't guarantee effective repairs or lower tailpipe emissions.

Instead of specifying technology, the federal Clean Air Act of 1990 specified performance standards for the emissions of hydrocarbons (HC), carbon dioxide (CO) and oxides of nitrogen (NOX). Emission control system malfunctions are defined as anything that causes tailpipe emissions to increase beyond 1.5 times that specification. With increased on-board computing power, emissions control became integrated into the engine management system.

This is one of the major differences between OBDI and II. The computer uses software to monitor a whole system, not just reference circuits to monitor individual components. With each new generation of more powerful on-board computers, OBDII has become more capable and refined. In addition to monitoring devices, OBDII monitors its own internal logic and can record a sequence of events that point to the cause of a failure. Today's fault codes and live and freeze frame data are more detailed and infinitely more useful to a tech in determining what failed first and why. It's not perfect, but for skilled technicians, off-board diagnostics is now an exercise in following the trail marked by OBD.

In addition to monitoring emissions, OBD also monitors brakes, air bags, security systems and almost anything else on the car with a wire connected to it, even light bulbs. However, emissions monitoring is still the most challenging diagnostic because the only exhaust gas OBD can measure directly is oxygen. To detect a problem that might increase HC, CO or NOX, it can monitor only the performance of the engine and its systems. OBD must calculate if a malfunction that has occurred will increase emissions beyond the allowable limit. Because of this, some items can be monitored only under specific operating conditions, and to avoid false warnings, some malfunctions must occur more than once before the OBD program will set a hard code and illuminate the malfunction indicator lamp (MIL).

Even so, the latest generation of on-board computers has made today's OBDII so reliable that most states have already eliminated tailpipe emissions testing for newer vehicles in favor of a simple check of the OBD monitors and codes. Because the average car on the road is now more than eight years old, most are OBDII, so tailpipe emissions inspections eventually will go away completely. If regulators are prepared to rely completely on OBDII for monitoring vehicle emissions, then the basic strategy of OBD — calculating emissions levels by monitoring the engine management system — will remain the same for the foreseeable future. But that doesn't mean OBDII won't change.

Change has already begun

An oft-repeated prediction attributed to Charlie Gorman of the Equipment and Tool Institute says that OBDIII will be OBDII with wireless communication. Gorman said this in 2001, when it became clear that tailpipe testing was on the way out and California had already begun experimenting with broadcast OBD.

In 2004, the U.S. Environmental Protection Agency (EPA) approved Oregon's plan to implement a wireless emissions inspection program, and its initial testing began earlier this year. But wireless inspections are only one of three options being tested there.

Oregon has always had centralized emissions inspection, and this new program is aimed at eliminating the need for appointments and the long wait at the inspection lanes. One option being tested is the self-service inspection kiosk, open 24/7, which looks a bit like a modern-day telephone booth with a long cable and an OBDII connector. The driver inserts a credit card, unreels the cable and plugs it into the vehicle. The VIN and appropriate OBD data are transmitted to a central computer, along with a photo of the car. If the car passes inspection, a sticker can be issued on the spot.

Another option being tested is the Internet/mail-in OBD. The vehicle owner obtains an approved data recorder that plugs into the OBD connector (they're available in parts stores now). A light on the recorder indicates when the test is complete, and the recorder (and payment) can be mailed in to the state, dropped off at a test facility or even downloaded to the state via the Internet through a personal computer.

The third option is a low-cost transmitter that broadcasts information obtained through the OBD connector while the vehicle is being driven. Broadcast range is limited, and there are a number of receivers scattered around the city of Portland.

Other options of OBD testing

Assuming that broadcasting is at least part of the future of OBD testing, there are several ways to do it. Ed Lipscomb, SPX Diagnostic Systems' product manager, says we could use inexpensive transponders similar to those used for electronic toll collection. They could be event-triggered, programmed to broadcast only if the MIL is illuminated. While the state would have to install and maintain receivers, it would eliminate the test lanes, so the cost to the state might be a wash, and motorists would never have to make an appointment or wait in line. Long-range satellite-based technology also is available, using existing GPS and vehicle tracking system infrastructures. However, the motorists would have to buy expensive transmitters and pay subscription fees, and there would be some thorny privacy issues involved.

The most likely technology for broadcast OBD is cellular telephone. It's relatively inexpensive, the infrastructure and its support system already exist and it's fast becoming built-in equipment on a significant portion of fleets. Of course, we're talking about OnStar and ATX, the two biggest providers of on-board cellular communications in North America.

As an inspection tool, cellular technology's biggest advantage is two-way communication. An automated system could "call" the car and carry out inspections on a specific schedule, and the car could automatically call the inspection system if the powertrain control module (PCM) sets a hard or pending fault code. Should the car ever fail inspection or turn on the MIL, the state can call the car to notify the driver, and it can inspect again later to confirm a repair or take further action if not repaired.

What would make this system acceptable to the public? According to Steve Liao, founder and president of MechanicNet, it's consumer interest in the many features available with two-way vehicle communications, such as remote door unlocking, emergency services, roadside assistance and of course, as shown in the television commercial, a direct link to the OEM service network.

Popularity of 'as-needed' maintenance

Aside from emissions inspections, there are other reasons for combining on-board diagnostics and telematics. According to an SAE paper written by Delphi engineers developing Remote Diagnostics and Maintenance (RD&M), a vehicle equipped for RD&M will probably communicate with a central diagnostic computer, even while parked and turned off, not just when there's a problem. The RD&M server will keep detailed records of that vehicle, including an equipment list, maintenance and repair history and even drive-cycle logs. It will analyze this along with the vehicle's current on-board data and notify the owner when it's time for maintenance. The goal is to control maintenance costs by replacing parts and fluids only when they're really needed, as opposed to relying on a time-or mileage-based schedule. The idea of as-needed maintenance is becoming more popular in the industry, especially with OEMs that wish to reduce the cost of ownership without reducing vehicle reliability.

Today, it's easier to extend maintenance intervals without risking vehicle reliability or service life because almost anything with a wire connected to it is being monitored already, and the number of items monitored will increase dramatically in the next decade. RD&M makes on-board data available off-board so maintenance requirements can be determined remotely by a more powerful computer with more complete maintenance records.

As its name implies, RD&M communication is two-way, meaning the vehicle can download software updates and messages for the driver from the RD&M server. If that server determines that a mission-critical or safety issue needs immediate attention, it can reduce performance in some non-critical area, such as audio or HVAC, making it more likely the vehicle owner will seek service.

Looking at a bigger picture

There's one more version of remote diagnostics in the works that doesn't rely on wireless communication, although it could be combined with broadcast technologies already discussed. A company called The ETAS Group, which includes a division of Vetronix, is an automotive engineering and software developer based in Germany. Its focus is on the OEM market, and the ETAS vision of the future of automotive diagnostics is nothing short of revolutionary.

Today, the OEMs use three different communication protocols or "languages" to communicate with the vehicle through the OBDII connector; that's why even the best scan tools have trouble communicating with some vehicles. They also use proprietary protocols for dealer scan tool communication.

The ETAS Group's plan calls for one universal service bay computer that can interpret all of those protocols. Called the Modular Vehicle Communication Interface (MVCI), it will act as a server/translator for all communications with any vehicle. Through the MVCI, the vehicle can connect with off-board equipment such as scan tools, PDAs, scopes, meters and even shop management tablets. It would also communicate with a desktop or laptop personal computer running a standard operating system that can connect to other tools and to the Internet. With the MVCI, information will be exchanged in both directions as whole data instead of computer code.

When the car is in the service bay, those manufacturers who participate in the ETAS plan will receive data directly from the vehicle over the Internet, allowing them to build a database of fault/repair histories. Service information, service bulletins and program updates coming back to the service bay from the manufacturer will be based on intimately detailed feedback from the whole population of vehicles made by that manufacturer.

How will this impact OBD? Under the ETAS program, diagnostic and service information will be based on the same software used to develop the vehicle for production, to program and calibrate the vehicle at the factory and to develop and calibrate every other vehicle from that manufacturer. The same software will also be used by every other participating manufacturer for development, calibration, diagnostics and service. Although we in the aftermarket have reason to be skeptical of the term "universal" (our term, not theirs), ETAS has already obtained cooperation from Volkswagen/Audi, DaimlerChrysler, General Motors, BMW and Fiat, and they're only three years into the plan. If their vision comes true — and there's a lot of money and power behind it — there will eventually be one tool and one software platform for communicating with every vehicle in the fleet. The service tech, whether dealer or aftermarket, will be able to access the OBD system and interpret the data it reports using exactly the same tools and techniques on every car.

Of the possible futures for OBD, a universal software platform and data-based as opposed to code-based communications would be the most radical change of all. For the aftermarket, its cost/benefit ratio is still undecided, because it would require repair shops to invest in yet another layer of equipment and education. Of course, that might be the case with these other possibilities, too.

But one thing is certain: No matter how we ultimately define OBDIII, it's still just a tool, and your professional customers will need the training and resources to put it into action.