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Scan tool quick checks

Maximize your scan tool use for fun and profit
Monday, October 19, 2015 - 07:00
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Over the years, the bread and butter in the automobile repair shop has been regular service and repair of vehicles. The first thing that comes to mind when we think of servicing a vehicle is doing an oil change or performing a brake job. As simple service has evolved into the more complex “scheduled services,” the need to start hooking up a scan tool and see what is hiding behind door one, two or three is very important. 

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There are always those vehicle inspections that management keeps shoving down our throats, too. Now on the other hand, have you noticed that the vehicles we work on today are requiring less and less service and maintenance than they did even 10 years ago? So why not start using the electronic diagnostic equipment that is sitting in our toolboxes to make life in the bay a little easier? I don’t think a scan tool will ever replace the need for a well-trained technician that is proud of their craft, but it will sure help them out.

More uses than ever
Over the years, I have made many learning projects in my shop, which required the use of scan tools. Things like understanding fuel trim and how to use the data to point toward drivability problems, or the use of the scan tool to analyze charging system problems are two that come to mind, but I think the scan tool can be used in many other ways to bring easy cash to both the shop and the technician.

As the flood of technology gushes past our shops, are you aware of the gravy that is floating on top? By this, I am referring to the amount of resources available to the scan tool user; not only data, but the bi-directional controls of the tool. Late-model vehicles have data stream for most everything on the vehicle: lights, cruise control, climate control, antilock brakes, traction control, stability control and the list goes on and on. Every electronic control module has data and will store diagnostic trouble codes, which can be a gold mine in the hands of an experienced scan tool user. So why should you be hooking up a scan tool to a seemingly good working vehicles? Let me give an example.

The vehicle in the shop is a 2011 GMC Terrain. Under the hood is a 2.4L gas direct injected (GDI) engine. There are 67,000 miles showing on the odometer; the vehicle is well maintained, drives great and has no known problems. I work in a small independent shop, and my scan tool of choice for a job like this is an aftermarket scan tool, which will hook up quickly and communicate with most modules on the vehicle. I also have OE scan tools for the hard-to-fix problems.

With the scan tool hooked to the vehicle, my first stop is the screen shown in Fig. 2, the menu of modules. This allows several different choices, but in the upper left corner is an option labeled “code scan.” By choosing this option, the scan tool will poll all available modules on the vehicle and report any diagnostic trouble codes that have been stored in those modules. Please don’t think if there are some codes stored, the scan tool is indicating the needed parts for the job. The diagnostic trouble codes (DTCs) only point to a place to start, or you might say they will give the technician a direction to start their process of problem analysis. In this case, the technician is only using the scan tool as a tool to sell service or needed repairs.

Think of the possibilities the scan tool gives the technician by being able to look in all modules for lurking problems. Since most vehicles use a module to operate the lighting system, a DTC will be set if something as simple as a light bulb is not functioning properly. How easy is it to sit in the front seat and have the scan tool tell you there is a stop light bulb out? I like this!

Back to the scan tool data. This DTC check takes about one or two minutes on this vehicle. The data displayed in Fig. 3 shows the report from all modules. In this case there are two modules with DTCs stored — the airbag module and the lift gate module.

The next screen, Fig. 4, shows each module, and the DTCs that are stored. The DTCs stored in both modules are U-codes, which are communication codes. At this point, I will not peruse these, since there are no reported problems with the components these modules control.

While we are browsing through the different scan tool functions, let’s stop and take a peek into the Body Control Module (BCM) and see what information is available. Fig. 5 shows a lot of different areas to access information. At the top left is the charging system data. This vehicle has a smart charging system and using the scan tool data is a great way to start a charging system problem analysis. Fig. 6 is a screen shot of the data available for the charging system. This can be very valuable information when testing for a charging system problem. Unless the technician knows for certain the BCM has commanded the generator on, any other testing can be a waste of time.

Each year as new vehicles arrive there is always a change in technology, and I would rather work on a late-model vehicle than a 20-year-old vehicle. I love using a scan tool and the vehicle data that is displayed. This is another reason I want to hook up a scan tool to every car that is in my shop for any major service. The scan tool in the hands of an experienced person can give a heads up to problems that are lurking in the wings, but have not reared their ugly heads.

Fig. 1: A six speed automatic transmission, with all-wheel drive comprises the powertrain. The odometer is showing 67,000 miles have been traveled. 

Fig. 2: Each of these modules has a possibility of a problem. By clicking the “code scan” button in the upper left, the scan tool will do a code scan on all the available modules on the vehicle. 

Fig. 3: With the information on this screen, it is easy to see which modules have any diagnostic trouble codes. The only diagnostic trouble codes that turn on the check engine light are emission related codes. A DTC stored in any other module will NOT turn on the CEL unless it is an emission related DTC.

Fig. 4: The report shows two modules  have DTCs stored. All DTCs are U-codes, which in this case are can-buss faults. There are no reported problems with this vehicle, so I will not peruse them.  Fig. 5: Screen shot of the different data options found in the body control module. Each of these data options has both data and bi-directional control options. These functions make the use of a scan tool very worthwhile when it comes to finding and fixing a problem. Fig. 6: This is the data needed when testing for a charging system problem. 
























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