Airbag control unit with part number 985155DC0A

What is the function of the airbag control unit 985155DC0A?

The airbag control unit 985155DC0A is the central control module for the occupant restraint system (SRS) in the Infiniti QX30 H15. As an OEM component from Infiniti, it processes data from crash sensors and determines whether to deploy airbags and seatbelt pretensioners, thereby providing optimal protection for vehicle occupants in the event of a collision.

Technically, this control unit—also known as the Airbag Control Unit (ACU)—is responsible for continuously monitoring the functionality of all SRS components, including front and side airbags, seatbelt pretensioners, and both external and internal acceleration sensors within the vehicle.

In the event of a collision, the electronics analyze incoming sensor data within milliseconds. If the measured values exceed predefined thresholds, the control unit sends ignition signals to the appropriate restraint systems, ensuring their timely activation.

Why does the control unit 985155DC0A fail?

The most common cause of failure for the control unit 985155DC0A is the storage of crash data in its internal EEPROM or flash memory following a collision. Other causes include internal electronic malfunctions, such as faulty sensors or communication errors, as well as hardware damage to components or solder joints on the circuit board.

After deploying airbags or seatbelt pretensioners, the control unit locks itself by storing a crash record that cannot be erased using standard workshop tools. This is a safety feature designed to mandate a thorough system check, resulting in a permanently illuminated SRS warning light.

Electronic faults may manifest as error messages related to internal components like acceleration sensors or communication issues over the CAN bus. In these cases, the control unit often becomes inaccessible via diagnostic equipment or reports an internal memory error.

At the hardware level, thermal stress and vibrations over time can lead to defects at solder joints, particularly in BGA chips. Additionally, the failure of individual components such as voltage regulators or driver ICs can disable the entire device.

This control unit is technically closely related to and compatible with Infiniti part numbers 985P05DC0A, 985H15DC0A, and 985P15DC0A. The fault patterns are identical across these units.

How do you recognize a defect in the 985155DC0A?

A defect in the control unit 985155DC0A primarily manifests as a persistently illuminated airbag or SRS warning light on the instrument cluster. Reading the fault memory typically reveals entries such as “Crash data stored,” “Internal control unit error,” or specific error codes associated with internal sensors that cannot be cleared.

The clearest indication is the active SRS warning light, which remains lit even after restarting the engine. This signals a serious malfunction in the restraint system requiring immediate inspection.

In the workshop, the fault memory often cannot be cleared, especially after a collision. The diagnostic tool then reports a persistent error indicating stored crash events, making repair or replacement of the control unit unavoidable.

Rarely, the control unit may fail to respond to diagnostic requests altogether. In such cases, there is usually a severe internal hardware or communication fault.

In which vehicles is the 985155DC0A installed?

The airbag control unit with part number 985155DC0A is an OEM component specifically fitted in the Infiniti QX30 of the H15 series. At Airbag24, we repair this control unit for all variants of this model produced between approximately 2016 and 2020.

At Airbag24, we specialize in restoring this control unit for the following model:

Infiniti: QX30 (H15 series, manufactured circa 2016–2020)

How does repair proceed at Airbag24?

Upon submission to Airbag24, the control unit 985155DC0A undergoes professional diagnostics. Technicians read the internal memory to remove crash data or analyze any faults. Defective components are replaced, and solder joints are reworked. A final test on a bench ensures full functionality. We provide 2 years' statutory liability for defects on every repair.

First, the workshop should confirm that the issue lies within the control unit itself rather than in external components such as cables or sensors. After removal, the unit is securely packaged and shipped to us.

At Airbag24, we perform an initial inspection and conduct a detailed analysis of the circuit board. Using specialized equipment, we read the memory (EEPROM/Flash). Stored crash data is carefully removed, or damaged data blocks are restored.

If a hardware defect is present, faulty electronic components such as voltage regulators or driver ICs are replaced with new, high-quality parts. Critical solder joints are professionally reworked.

Finally, we simulate the vehicle environment on a specialized test bench. During this process, communication and the proper functioning of all internal circuits are thoroughly checked to ensure the control unit operates flawlessly once again before it is returned.