Airbag control unit with part number A1679008601

What is the function of the airbag control unit A1679008601?

The airbag control unit A1679008601 is the central control module for the occupant protection system in the Mercedes-Benz GLS-Class, X167 series. It continuously monitors all relevant sensors, such as crash sensors and seat occupancy detectors, processes their data, and ensures that, in the event of a collision, the airbags and seatbelt pretensioners are deployed precisely and within seconds.

Technically speaking, it is a highly complex ECU (Electronic Control Unit) that serves as the brain of the entire passive safety system. It receives signals from acceleration sensors mounted at strategic points on the vehicle body, as well as from pressure sensors and seat occupancy mats. Based on this information, the microcontroller inside the control unit determines whether and which restraint systems need to be activated.

Proper functioning of this module is vital. If it fails or malfunctions, occupant protection can no longer be guaranteed, as airbags and seatbelt pretensioners may fail to deploy or deploy incorrectly in an emergency. For this reason, professional diagnosis and repair are essential when defects occur.

Why does the control unit A1679008601 fail?

The most common causes of failure for the control unit A1679008601 are stored crash data following an accident, as well as electronic faults on the circuit board. Internal components such as memory chips (EEPROM/Flash), voltage regulators, or the microcontroller itself can suffer damage due to aging, moisture, or vibrations, leading to complete failure.

A very common cause is the storage of crash data. After an accident—even if not all airbags were deployed—the control unit writes an irreversible event into its internal memory. This safeguards safety and prevents re-use of a potentially damaged system. The control unit then becomes locked and displays a permanent error code, even if the hardware itself remains intact.

In addition, purely electronic faults can lead to failure. These include damaged traces, cold solder joints on SMD components, or the failure of specific parts such as voltage regulators or microcontroller peripherals. Such damage often develops gradually due to thermal cycling (hot/cold), vibrations during driving, or ingress of moisture that causes corrosion at connectors and contacts.

Loss or damage to configuration data stored in non-volatile memory (EEPROM/Flash)—for example, caused by a sudden power interruption or an internal short circuit—can also render the control unit inoperable.

How do you recognize a defect in the airbag control unit A1679008601?

A defect in the airbag control unit A1679008601 primarily manifests as a permanently illuminated airbag or SRS warning light on the instrument cluster. Often, the control unit can no longer be read with a diagnostic tool, or an internal, non‑erasable fault code appears, indicating a hardware malfunction.

The clearest symptom is the activated airbag warning light. It does not turn off after starting the vehicle, signaling to the driver that the restraint system is not operational. This is a critical safety warning requiring immediate inspection.

Another clear indication is the lack of communication with the control unit. When a workshop attempts to read the fault memory via the OBD interface, the airbag module no longer responds. It becomes unreachable to the diagnostic scanner, pointing to a severe internal fault.

Following a crash, the system also remains deactivated, with the warning light still on. Even after the vehicle has been repaired, the crash data stored in the control unit prevents reactivation of the airbag system until the module is repaired or replaced.

In which vehicles is the airbag control unit A1679008601 installed?

The part number A1679008601 is specifically designed for the Mercedes-Benz GLS class, X167 series. Due to the complexity of vehicle electronics, precise matching of the part number to the vehicle model is crucial for successful repair and full compatibility.

At Airbag24, we repair the airbag control unit with part number A1679008601 for the following model:

Mercedes-Benz GLS-Class X167 SUV (from model year 2019 onward)

How is the control unit A1679008601 professionally repaired?

Professional repair of the A1679008601 involves detailed diagnostics on a test bench, elimination of hardware defects at the component level, and restoration of the original software data—including deletion of crash records. Final functional tests ensure full operability and safety.

After submission to Airbag24, the repair follows a rigorous, quality-assured process. It is advisable to document the fault codes with a diagnostic tool before removal and include them with the package, providing technicians with valuable initial information.

First, an incoming inspection is performed on a specially designed test bench. Here, power supply, bus communication, and diagnostic access are tested. Subsequently, the housing is opened under ESD‑safe conditions to visually inspect the circuit board for damage such as cracks, cold solder joints, or leaking components.

The actual fault localization is carried out using measuring instruments like multimeters and oscilloscopes. Defective SMD components—whether voltage regulators, memory chips (EEPROM/Flash), or other peripheral components of the microcontroller—are identified and professionally replaced using dedicated rework stations.

A key step is data service: the contents of the memory are read out and backed up. If crash data is available, it is reset; if configuration data is damaged, it is restored. Upon completion of the hardware repair, a comprehensive functional test is conducted, simulating sensor events to verify the control unit’s correct response.

Following a successful test, the control unit is sealed and returned with a test report. After installation in the vehicle, only any remaining system‑wide fault codes need to be cleared. We provide 2 years' statutory liability for defects on all repairs.