Finding Gremlins Electronically
M-B Computer Assistance

Let’s take a look at how dealership technicians navigate the information superhighway to solve and repair problems, starting with malfunction fault codes.
Where do we look for the most up-to-date information? Where do we search for testing and repair data? What about repair manuals, which are not on printed media these days? This information has been delivered in so many different formats that finding an appropriate match to the symptom can sometimes be a daunting task.
The Star Diagnostic System (SDS) is our first weapon of choice. (Well, actually, we don’t have a choice.) SDS consists of a touch-screen tablet-style laptop, connected wirelessly to an interface that is usually plugged into the On-Board Diagnostic (OBD) II connector in the left footwell area of the vehicle. (See pictures above. ) On older cars, such as the W210 and the W140, it is located under the hood. In the case of a dealership SDS, we are also connected to Mercedes-Benz for direct coding of control units and other functions. More on that later.
Generally, when we are investigating a specific fault, for example, a check-engine, or a brake-system, warning light, we start with a “quick test.” For this example, I will use a 2005 E350. A quick test is a scan that checks at all the computers and systems in the vehicle. A total of 39 computers are queried on this scan. It is important to look at the big picture here. Often one failure can trigger codes in other systems that sharea data exchange. In other words, you need to be sure you are chasing the root problem as opposed to a subsequent fault code. The first screen we see after running a quick test is a summary of all systems on the vehicle, with the part number of each control unit and, next to each item, an indication of the condition of each system. In this column, we see a check mark indicating that there are no faults, a lower-case “f” if there is a fault stored, an upper-case “F” if the fault is current, or an “i” to indicate that an event has occurred. By clicking the magnifying-glass icon at the bottom of the screen, we access details of the actual fault or event that is occurring or has occurred.
Now that we know the fault code, what do we do with it? From the summary screen, we can click the particular system we need to investigate. This will pull up another menu for options within that system, such as fault codes, control module adaptation, actual values, control module programming, and other various options. Clicking “Fault Codes” takes us to a list of all the faults, either stored or current, in that control unit. Clicking a particular fault code takes us through a series of guided tests specifically to address the fault code we are investigating, complete with connector locations and diagrams on the newer vehicles.
SDS gives us the ability to do much more than just diagnosing fault codes. With this piece of equipment, we have the ability to update software within a control unit if needed. We can transfer settings and version coding from a bad control unit to the new one being installed. Sometimes this can save us quite a bit of time over the manual entry of line after line of vehicle equipment data. Control units need to know exactly which equipment and options are installed to operate properly. We can view real-time streaming data from systems such as transmission, engine, and suspension, to name a few. These days, manufacturers are using the same control units on a wide variety of vehicles by simply programming them to the vehicle on which they are installed, thereby reducing the need for so many different part numbers to be stocked on shelves and lowering costs.
What if the fault codes are not providing a clear direction to the cause? Another resource is available to dealership employees through NetStar, a secure online portal to Mercedes-Benz. Over the years, technology has changed at a staggering pace, and, as a result, so has the way we store and share repair data with fellow technicians. One way the information is shared is via Dealer Technical Bulletins, which offer many fixes to common problems. The chances of getting good hits here have been somewhat hindered by a poor search engine. For newer vehicles, we have a new database, TIPS, which is beginning to be very helpful. In the TIPS database, we are required to enter the full VIN so that the information we collect applies to a specific vehicle and options, and hopefully avoids taking us down the wrong diagnostic path. There are now many interactive diagnostic guides for the more complicated systems. We also have online wiring diagrams within NetStar with component locators and access to the electronic parts catalog.
The Workshop Information System (WIS) is our electronic version of a shop manual. It’s where we find information on how to remove and repair each component, along with torque specifications and other test data. WIS, also accessed through NetStar, is loaded on the SDS computer. Obviously, this technology is proprietary to Mercedes-Benz dealerships, but Mercedes has made much of the information available to the public. I strongly suggest you log on to startekinfo.com and browse around. On the left, click “Subscribe,” agree to the legal terms, and you will be directed to a page that displays the costs by the day, week, month, and year. Be sure to return to the homepage and click all the links for a good look. With any subscription, you can access Service Bulletins, wiring diagrams, WIS, workshop resources – most of the information technicians can access. Whether you are a weekend warrior or an aspiring technician, do yourself a favor and subscribe at some level. You’ll be happy you did.