Accessing Repair Data: A Report from the Field

Accessing Repair Data: A Report from the Field

Today, a diagnostic technician is dealing with networked computer systems that are impervious to reverse engineering and other diagnostic techniques.

A few years ago, I had a young lady notice that I had about 20 linear feet of repair manuals shelved along the wall of my shop. Gazing at the repair manuals, she blurted, “Gee, I didn’t know that an auto technician had to know how to read, let alone own that many books on how to repair cars!”

Far from being taken aback by that statement, I explained that those manuals covered old cars not found in my then-new computerized information system. I further explained that (at that time) my computer contained about 1.5 million pages of printed data that was written at the 14th-grade level. “So yes,” I explained, “a technician not only must know how to read, but he must be able to comprehend abstract information written at the college level in order to do his job.”

Unfortunately, the idea that technicians don’t need information skills isn’t limited to the ranks of consumers. I’ve encountered the same attitude from when I served on a state vocational teaching standards committee five years ago. A female administrator with a doctorate in education asked me if, indeed, auto technicians were required to know how to read. “Of course,” I responded, “not only do they need to know how to read, but they must be computer-literate as well to access current technical information.”


Thirty years ago when all vehicle functions were performed by mechanically operated systems, a good technician could “figure out” how a component worked by taking the component apart and reassembling it. In modern terminology, this process is known as “reverse engineering.” Reverse engineering, augmented with the data supplied by paper shop manuals, trade magazine technical articles, and technical service bulletins printed in trade magazines, was all that was needed to diagnose and service most mechanically controlled vehicles. But, as vehicles became electronically controlled, reverse engineering became more complex. Instead of disassembling and reassembling a component, a technician was forced to observe how various electronic inputs into a processor assembly would affect the processor’s electrical outputs. A technician could also reverse engineer systems by analyzing a processor’s electrical signals with a digital storage oscilloscope (DSO). These methods sufficed as long as the vehicle had only one on-board computer controlling its engine and automatic transmission functions.

Beginning in the late 1990s, auto manufacturers began installing smaller computers or modules to monitor and control heating and air conditioning, braking, air bag, anti-theft, and vehicle stability functions, just to name a few. An entry-level domestic vehicle might have four on-board modules while a more luxurious model might have a dozen modules to monitor and control myriad mechanical functions. High-end European vehicles currently have 70 or more modules. Today, a diagnostic technician is dealing with networked computer systems that are impervious to reverse engineering and other diagnostic techniques. Not only has the service information has become so voluminous that it has become physically impossible to store on a library shelf, the information itself has become so esoteric and application-specific that it requires a computer to classify and retrieve in a timely manner.


Modern service information might be classified into five basic categories: training, diagnostic, repair, technical service bulletin, and calibration information. Training information describes how a component operates and what basic procedures are required for service. Diagnostic information contains the specifications and step-by-step processes required to locate a problem in an operating system. Repair information contains the mechanical specifications and step-by-step processes required to repair the system. Technical service bulletin information includes the most recent changes in diagnostic and repair specifications and procedures.

Last, and most important, is the calibration information required to program or re-program on-board computers and modules. Since 1996 when OBD II on-board diagnostics were widely introduced, very few powertrain or body control computers would be installed on a “plug-and-play” basis. Given the dozens and perhaps hundreds of chassis and equipment configurations available in any car line, it’s virtually impossible for an auto manufacturer to supply “plug-and-play” computers. Instead, the vehicle identification number (VIN) information must be used to configure the computer’s software to the vehicle’s mechanical and electronic configuration.

Obviously, modern service information is too voluminous to publish in a paper manual. Although electronic calibration data was once contained on DVDs, it must now be downloaded from an auto manufacturer’s Web site through an aftermarket “pass-through” reprogrammer or into a factory scan tool for downloading into the computer or module that’s being replaced.

Currently, most of the Original Equipment Manufacturer (OEM) technical service bulletins and repair information are available through two major aftermarket service information companies. These companies edit the OEM information into an electronic format that can be supplied to shops online or by DVDs that can be read by the shop’s computer system. Calibration data, on the other hand, must be downloaded from an OEM Web site through an aftermarket programmer or through an OEM scan tool or PC-based OEM diagnostic system into the vehicle’s on-board computers and modules.


Given the relative complexity of accessing on-line service information, it’s understandable that many independent auto repair shops feel that critical service information is being withheld from them. The information issue was relatively simple when all emissions-controlled vehicles had single on-board engine control computers. The information access issue was clear-cut because the Environmental Protection Agency (EPA) required that all emissions-related repair information be released to independent shops.

The information issue became critical only when multiple on-board computers were used to operate non-emissions systems like body component, comfort control, safety, and security systems. Because auto manufacturers didn’t release non-emissions information, many independent shops justifiably felt that they were being denied the information they needed to repair modern vehicles.


During the late 1990s with the continued proliferation of multiplexed electronic control systems, the information access issue became critical to the survival of the independent repair shop. The issue was eventually laid upon the doorstep of the Senate Commerce Committee in July, 2002. Instead of going through the process of introducing new legislation, Committee Chairman Byron Dorgan, D-N.D., requested that independent repairers and automakers discuss gaps in emissions and non-emissions-related service information.

This discussion resulted in a written agreement that led to the formation of the National Automotive Service Task Force (NASTF). Since then, NASTF has served as a forum through which the industry can address the availability of service, reprogramming, tooling, and training information between the independent service and auto manufacturing sectors. An on-line visit to will answer most of the questions concerning current issues concerning information access for independent shops. Of course, any online technical information costs money to write, edit, and publish. Auto manufacturer’s one-time access charges range from about $20 for mass-produced vehicles like Chevrolet or Toyota to more than $100 for limited-production vehicles like Porsche or Maserati. Monthly and annual rates are also available. Nameplate specialty shops often use the OE tooling and subscribe to the OE information by purchasing new-generation, PC-based, diagnostic and information systems that generally cost in the $6,000-8,000 dollar range.


The short answer, of course, is “no.” Although conventional paper shop manuals have always been expensive, some shop owners nevertheless feel that online information should be available for free. Other shop owners simply don’t have online access and therefore don’t know that on-line information availability currently exists.

At another level, replacement part manufacturers feel left out of the process because the encoded information required to produce components that use digital logic to communicate with other components isn’t generally available. But this level of concern may have more to do with intellectual property and patent rights than it does with the overall access to service and repair information. Whatever the future may bring, OE service information will continue to be a highly sought-after commodity in the automotive aftermarket.

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