Case Studies

Mercedes Magical SAM Module – Solving Electrical Problems and Keeping SAM Happy

This Mercedes presented with multiple external lights out, or not working correctly.

Locating the “SAM” under the coffee cup holder may not have been the best of design decisions. Then again, Europeans don’t really eat or drink in their cars.

So What’s A SAM?
SAM stands for Signal Acquisition Module in the Mercedes world. A SAM module receives data from sensors, switches, and controllers, and can send data, actuate (activate) components, and monitor systems.Mercedes-Benz has been using SAM modules since the mid-90s. SAMs come in a number of shapes and sizes, depending on where they are located on the car. Some are part of the fusebox, some are separate modules, most Mercedes usually have between four and five SAM units, depending on the complexity of the vehicle and systems.

Cool Technology
SAMs are very cool technology, replacing literally hundreds of discreet wires with a two or three-wire data network. They are usually super reliable and make your car more reliable…unless they get wet.

One of the top failures in the SAM control modules is water or in this case, liquid coffee damage, which leads to corrosion and eventual failure.

Typical Problems that cause SAM failure
Corrosion –  It is possible that the SAM control module may have gotten wet, corroded, and eventually failed. Typically this is caused because the repair is performed near the SAM control unit. If the SAM modules are not closed and sealed, properly they will eventually corrode. If a SAM module fails due to corrosion, at first you may notice that electrical problems are intermittent.

Excessive Current Draw – SAM control units don’t fail often. Other than physical damage or corrosion the next most likely cause to make your SAM unit fail is an excessive current draw. If you’ve done modifications to your Mercedes-Benz or have a module that is drawing too much current that can damage your SAM unit.

Broken Wires – Broken wires or shorts can cause your SAM module to fail due to excessive current draw. We this often with rodent damage or insulation that has broken down.

Incorrect SAM Coding 
– If you just had your MB serviced and now you have a different problem it is possible that there is a programming issue. During a repair, a technician may have reprogramed a new sensor but they didn’t complete all the needed programming. If this is your situation, t is important to read all fault codes before you start doing any troubleshooting on your Mercedes-Benz.

In the early model years, you could replace the SAM unit with a used SAM from another Mercedes-Benz and not worry about any programming. Newer Mercedes-Benz models require SAM module programming and the new SAM unit will need to be coded with the Sofware Calibration Number (SCN). You will need to replace it with a new one if you need a SAM. The new SAM module will need to be coded and programmed using the Star Diagnostic System (which we have at AMC) once it is installed.

The Proper Repair
The only true and permanent repair is to replace the SAM module and carry out programming, being certain that the cause of the failure, water entry, or other, is corrected.

At Atlantic Motorcar, we’re all about providing our customers not only Great Service but also Value. We understand that “An ounce of prevention is worth a pound of cure.” (my mom would be proud I remembered that.), in other words, preventing, or catching problems like these brake lines early, can save you more than just money.

Questions, or if we can be of help in any way with service on your Audi, BMW, Mercedes, Mini Cooper or other European (and now Japanese) import, please contact us.

Our team of Service Specialists is here to help, for even the newest autos!
Don’t hesitate to call us today, at (207) 882-9969.

Knowing, not just “doing”, that’s the Atlantic Motorcar way.

The Atlantic Motorcar Center Service Team

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