Technicians Play Key Role In OBD II Acceptance, Success
As a new generation of on-board diagnostic systems, known as OBD II, is slowly making its way into the marketplace, it's clear that the success of this introduction lies in the service bay. Making sure the system operates efficiently, and meets the objectives of government regulators and vehicle owners alike, is left to the technician. The answer lies in these professionals' ability to grasp and use new technology quickly.
 The BasicsOBD II diagnostic systems feature a code-setting process that includes a drive-cycle requirement. In most cases, disconnecting a sensor at idle will no longer set a code, and conversely, reconnecting a disconnected sensor will not clear a code that has been set. This makes it much more difficult to verify that correct repairs have been made or to detect when new problems are inadvertently introduced during the repair process. |
OBD II-equipped vehicles do not behave like their OBD I predecessors; their response can be unpredictable. It's an intricate system that's complicated by the introduction of an emissions detection element. This new feature focuses specifically on detecting emissions failures, not necessarily on controlling them like the previous generation processor did. Many of the new sensors have little impact on controlling fuel delivery or driveability.
While there is more overall code information available on OBD II systems, code setting conditions and other information isn't always well-defined by vehicle manufacturers. These conditions exist because manufacturers expect to revise or improve capabilities in future reprogramming (PROM) updates.
Much of the new information has proven useful. This has been the case with misfire codes, which uncover clogged or defective injectors.
The Learning Process Begins
All OBD II systems are not created equal. Vehicle manufacturers were allowed latitude in developing their own systems, so there are significant variations. Upon encountering these differences for the first time, it's difficult to determine whether something is operating normally.
For example, when codes are cleared on a majority of vehicles, most of the readiness monitors are also cleared and reset to NOT READY. This makes sense because the readiness monitors report the completion status of each on-board diagnostic self-test. The exceptions are the misfire, fuel system and component monitors, which always show READY, even with the engine off. How can the OBD system complete a misfire check if the engine's not running? The answer is simple, these monitors are always in the READY mode - as determined by EPA requirements. Additionally, there are a few vehicles that only clear the readiness monitors containing a code. So, if no codes are set, the status of the readiness monitors will not change. These inconsistencies about clearing monitors from one vehicle to another may lead to questions about the operation of the scan tool - but the real culprit is variation in each manufacturer's interpretation of the standards.
 As vehicle control technologies continue to change, the only way to avoid equipment obsolescence is to invest in equipment that's expandable and updateable. But software updates offer no guarantee. |
OBD II systems are still evolving. The new system's objective is to detect when component degradation or failure will cause emissions to rise by 50 percent. Several vehicle manufacturers introduced their first OBD II systems in the 1996 model year; expect to see them continue to refine their processes for a few years.
Some dealership service departments are already reporting a higher number of "false codes" on these systems. This is a condition where component failure detection limits are set too tight. The solution, in many cases, is to reprogram the vehicle computer. The true test may come as these vehicles are subjected to their first few emissions inspections, especially inspections incorporating loaded mode testing on a dynamometer. Vehicles failing the tailpipe emission test, which do not have OBD II fault codes set, may trigger a second wave of vehicle computer reprogramming.
 Shop Owners, Take NoteFor the independent shop, by the time OBD II systems begin to show up at their door on a regular basis dealership technicians will have ironed out most idiosyncrasies. Through experience, they will develop more effective diagnostic and repair procedures. But shops will still be required to invest in equipment updates and OBD II training. To effectively diagnose and repair any vehicle control system, the technician must understand how smart the system is and learn how it might react in a given situation. |
This new equipment will include evaporative emission testers and gas analyzers with a NOx channel. But existing shop equipment may only require updates. Any new equipment purchased needs to be more powerful, yet easier to use. It must aid a technician to identify what is and what's not a problem.
Shops should invest in software-driven and software-updateable equipment. A good scan tool and a good electronic circuit measurement tool are the building blocks. These tools should offer the following features:
- An easy-to-use interface or navigation system. If the interface is awkward or difficult to use, the unit isn't worth much. The only way to check a manufacturer's claims about ease of use is to experiment with the device. If you don't use it more than three times a week or you dread using it, you'll need to rethink whether this tool has a place in your shop.
- Updateable software. As vehicle control technologies continue to change, the only way to avoid equipment obsolescence is to invest in equipment that's expandable and updateable. But software updates offer no guarantee. It's important to deal with a manufacturer that has a track record of supporting its products over the long term.
- Built-in, application-specific information. These higher-priced, hand-held diagnostic units can function much as a PC does, offering computing and database power to deliver vehicle and system-specific diagnostic and repair information. With this feature, technicians will spend less time searching for information.
Training Required
Training is vital. Technicians will need to know how to work with a scan tool, an ignition scope, an electronic circuit measurement tool and information retrieval systems. Classroom and self-directed trade magazine training must be augmented by on-the-job training. The classroom will cover general operation principles and provide overviews of each OBD II system. Technicians must understand control system capabilities and how each specific system thinks.
It's not hard to foresee vehicle-specific training that's delivered on the job. There are too many vehicle control systems with too many variations to expect everything to be learned in a classroom. Equipment manufacturers will continue to embed more vehicle-specific test capabilities and information into their equipment, including details on test methods, test specifications, troubleshooting tips and vehicle update information. As testing methods improve and new problems are identified, more effective solutions can be delivered.
For OBD II to reach its full potential, technicians play a critical role. Standardization won't be offered anytime soon, so it's up to these professionals and their organizations to serve on the front lines - and ultimately lead the way.
Keith Kreft is director of engineering, diagnostics center of excellence for Snap-on Diagnostics, a business unit of Snap-on Tools Co. He has responsibility for leading product development efforts for the business unit's engine diagnostic products. In addition, he has participated in the development of Snap-on's hand-held and a variety of engine analyzer products offered under the Sun brand. Kreft is a member of the Society of Automotive Engineers (SAE) and currently serves as a director for the Equipment Tool Institute (ETI). He holds a variety of individual and joint patents for automotive engine analysis products.
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AutoInc. Magazine ®, Vol. XLV No. 6, June 1997