Mercedes can interface

Since I needed to replicate the steering wheel button functionality exactly some programming tricks need to be added. This would be difficult in Visual Basic. The program interface looks a little primitive, but here is another one of several different views: All the car's steering wheel buttons are replicated using a standard window's control and a little image of each is placed on top By clicking on one of the buttons, the corresponding steering wheel function of the car operates.

The program works great. Even though the application interface is overly simplistic, it can be used to build on and add more functionality at a later date. I plan to modify it add more functionality the more I learn about other PID's. Modify the hardware to allow wireless connection After playing around with the car functions and getting it to work, I had to show this to my wife.

Basically, all she said was "why are there so many wires". She's right. Too many wires. I had to address this. I own a BlueTooth FireFly module. Quite a nice device, so I thought it might work on my CAN At first attempt it didn't work.

It took a about 6 hours to discover why, which is my fault because I should have realized it at once. The CAN is configured for 3 wire connection, but the FireFox was connected originally for hardware handshaking, i.

A couple of dip switch changes later, the device was working with my favorite Windows terminal emulator program: remember ProComm? Back to debugging. The library is incredibly convenient to implement, and whoever wrote it deserves a lot of credit, but it didn't work. I still don't exactly know why, however I think the IVT Bluetooth driver in the handheld computer uses overlapped serial transmission and doesn't set up the call buffer quite right.

MSCOMM program didn't handle the serial Overlap interface and relied on the standard call, soooo the data wasn't read properly. It took about 3 hours to do the code modifications. It could have taken less time but I'm not familiar with this library. Now it's working again. I also had to build a power supply for the FireFly.

I took a voltage regulator, available from Radio Shack, and wired into the RS connector. The result is shown in the picture above. The module hides just under the dash below the drivers seat. Power is switched and taken from the cigarette lighter. Power wires have Power Pole connectors, only because I really like to use these babies since it is quick to connect and the module can be taken out of the car whenever needed. You can use whatever bluetooth adapter you can find for the laptop or handheld computer.

The FireFly's serial port is established as soon as the application opens the serial port. When the application terminates, or the serial port is closed, the bluetooth connection stops. Really nice. It will get you started. I took a slightly different approach and wrote an application that sorted the PIDs and displayed the data as it was changing in character form in real time.

Staying with OEM parts can help prevent problems. Using the wrong spark plugs or aftermarket filters can contribute to out-of-balance readings that will add up to a failure. Having an accurate vehicle service history might give some clues as to the cause of a fault.

With Mercedes-specific software and scanner capability, other codes will lead you to a specific component, but the diagnostic tree will go something like this.

Advertisement With the necessary equipment to read the data from the wheel sensors, the diagnostic tree leads you through road tests to check the speed signals, inspect for mechanical malfunctions like broken wires and damaged sensor rotors and sensor clearance measurements.

Then, the diagnosis goes to component replacement until the fault is resolved. That might work for a dealer, but for an independent shop, that is out of the question. Going further on the diagnostic tree, it usually sends you back out on the road, with a recheck of the sensor readings and then a control module replacement.

Advertisement The wild card, though, is the CAN bus itself. Electrical connections, relays, multi-plugs and power distribution problems can cause the kind of traffic jams that will cause the whole system to shut down.

Remember that since all of this information is transferred on one or two wires, in digital form, then decoded and acted upon in the main controller, it can take some time for the system to recover from even a small fault. My best advice is; make the basic inspections, and check and clear as many codes as possible.

Disconnect the battery for a half hour or so to allow the system to completely shut down, and then, if possible, follow the above steps. Digital Edition. Contact Us. Shop Owner. Special Content Video Webinars Podcasts. Magazine Current Issue Past Issues. Connect with us. Advertise Subscribe Contact Us. By Larry Bailly. By ImportCar Staff Writers.

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On Mercedes cars, CAN wiring has been incorporated since to allow the sharing of information that is used for the engine, transmission, airbag, anti-lock brakes and suspension control systems. Since these systems were first integrated into wiring harnesses, the ability of the controllers and control units to handle more information at faster speeds has made reliability a problem. Sometimes, what seems like an inappropriate operation is actually the way it was designed to work.

Unfortunately, it is not possible to add Apple CarPlay or Android Auto compatibility to a Mercedes-Benz model as an aftermarket accessory. Select Mercedes-Benz models offer Apple CarPlay and Android Auto as standard features, while other models only offer the technology with specific add-on packages from the manufacturer.

Therefore, if you purchase a Mercedes-Benz that does not have Apple CarPlay compatibility, you cannot add it afterward. If you are interested in buying a new Mercedes-Benz and want to ensure that it is equipped with Apple CarPlay or Android Auto compatibility, check with the sales team at Mercedes-Benz of Arrowhead.