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Anti-Theft System Faults in Your Mercedes From the Best Mechanics in Lowell

by Mechanics Direct November 4, 2019

Mercedes-Benz is known for engineering vehicles that encompass style, innovative technology, luxury, and state-of-the-art safety features. Due to their quality and performance, these vehicles are often targeted by individuals looking to steal a supreme ride. The team at Mercedes recognized this risk and designed an Anti-Theft Protection package to help prevent a break in and potential tow of their vehicles from their respective owners. However, while the package is a truly beneficial and a highly efficient addition to the long list of safety features, it can experience problems just as with any vehicle component.

Understanding the Anti-Theft Protection Package

Simply put, the anti-theft alarm system alerts the owner when the vehicle is opened without proper authorization. If there is an attempt to steal or break into the Mercedes, not only does an alarm sound, but flashing lights create a visual warning as well.

The system is activated when the driver utilizes the electronic key to lock the vehicle. The anti-theft alarm is then turned off as soon as the doors are unlocked again using the electronic key.

Activities like breaking windows, pulling on door handles, or trying to pry open doors will set off the alarm immediately. Owners who choose to activate the extended protection plan will also be alerted when there is movement in the interior or when the angle of the car is changed. In other words, if someone tries to tow your Mercedes away, the shifting angle of your car would trigger the alarm.

Issues That Can Arise with the Anti-Theft System

Some of the most common issues associated with the anti-theft system are the random and false alerts that can be triggered at inopportune times. These range from alarm sounds while driving to the indicator lights flashing without any sound at all.

Another significant problem relates to the operation of the vehicle. There are several components that are connected to the electrical system of the car. The ignition is also connected to the security system. If security sensors, such as the crankshaft position sensor, become disconnected, faulty, or damaged, the car will not start. This breakdown will keep the engine from being engaged at startup and will leave you stranded.

Various Reasons Alarm May be Triggered or Become Activated

Siren Module

This black, plastic, round canister is the “hub” of the alarm device. Although it is only about the size of a can of vegetables, it houses extremely-crucial components. These include the back up alarm batteries and the alarm sounder. It controls the electronics portion of the system. Over time, the NiHM batteries will wear down and cause the random alerts sometimes experienced by the driver.

SAM Module

A SAM control unit can be found in the trunk and can be vulnerable to extreme weather conditions. If water makes it way inside, the unit can fail. The SAM module controls the alarm system as well as the siren.


The actual battery found under the hood can also be the culprit when the alarm system malfunctions. If the weather gets bitterly cold, the car is parked overnight, or the battery gets too old, the voltage will drop. Any dip below 11.5 volts may cause the alarm to activate. This feature was included in the package design to make it impossible for a thief to unhook the battery in an effort to bypass the alert system.

Trunk/Door Hinges

Hinges that have become misaligned or damaged may trigger the system. These components tend to expand and contract in various temperatures and this movement may set off the alarm.

The Best Mechanics in Lowell Can Address Alarm Malfunctions

Mechanics Direct is your first-class auto repair shop, servicing the North Chelmsford, Chelmsford, Drycut, Tyngsborough, Westford, and Lowell, MA areas. This family owned and operated business has been diagnosing and repairing vehicles for over two decades. As a commitment to the best possible service, we pay our service department a salary instead of an hourly rate. This ensures that your vehicle will be inspected thoroughly and done correctly the very first time.

Anti-theft system failures in Mercedes must be diagnosed with specific equipment. Our expert team at Mechanics Direct has just that. We even provide a no-worry, 3-year, 36,000-mile warranty on repairs. This is designed to give you real peace of mind.