Airbag control unit with part number 285561N900

What is the function of the airbag control unit 285561N900?

The airbag control unit with part number 285561N900 is the central safety module in the Nissan Almera N15. Its primary task is to analyze signals from the acceleration sensors and, in the event of a crash, precisely deploy the airbags and seatbelt pretensioners. Additionally, it stores relevant crash data in its internal memory.

The control unit acts as the brain of the passive safety system. It maintains constant communication with the crash sensors distributed throughout the vehicle to detect an impending collision.

Upon detecting a deceleration indicative of a crash, the unit sends ignition pulses to the corresponding airbag modules and seatbelt pretensioners. After deployment, the device is often electronically locked, and the crash data is permanently recorded to ensure a thorough vehicle inspection.

Why does the control unit 285561N900 fail?

The most common cause of failure for the 285561N900 control unit is the storage of crash data after an accident, which triggers an electronic lock. Other typical issues include electronic malfunctions due to component aging, water damage from moisture ingress, or internal hardware defects that disable proper operation.

Following a collision in which the airbags have deployed, the control unit records crash data. This information permanently locks the system to ensure safe vehicle repair; simple erasure via a diagnostic tool is no longer possible.

Electronic malfunctions are another frequent source of failure. Over time, individual components on the circuit board—such as capacitors or processors—can fail due to thermal stress or aging. These failures result in internal errors that either appear in the fault memory or completely disrupt communication.

External factors like water damage can also lead to corrosion on the circuit board, causing short circuits or broken traces, which render the device unreliable or entirely inoperable.

How do you recognize a defect in the 285561N900?

A defect in the 285561N900 control unit is primarily indicated by the airbag warning light (SRS warning light) remaining steadily illuminated or flashing in the instrument cluster. Often, communication with the control unit via a diagnostic tool becomes impossible, or specific error codes such as “internal malfunction” are stored.

The clearest sign is the activated SRS warning light. This alerts the driver that the airbag system is not operational and cannot provide protection in the event of a crash. Driving with a lit warning light also constitutes a safety-related deficiency during the main vehicle inspection (TÜV).

Another clear symptom is when a workshop using a diagnostic tool cannot access the airbag control unit. The unit fails to respond to queries, indicating a serious internal fault.

Stored error codes may also point directly to the control unit itself. Messages such as “side sensor error” or “internal device fault” are typical. In some cases, the airbag error appears immediately upon starting the vehicle, without any specific error code being logged.

In which vehicles is the 285561N900 installed?

The part number 285561N900 is the original Nissan OEM number for the airbag control unit specifically fitted in the Nissan Almera N15 series. At Airbag24, we repair this control unit for both first-generation models and the facelifted versions of this series.

Specifically, this control unit can be found in the following models:

Nissan: Almera N15 (model years 1995–1998) and Almera N15 Facelift (model years 1998–2000).

How is the 285561N900 repaired?

Repair of the 285561N900 control unit at Airbag24 involves a systematic analysis at the component level. Upon receipt of the removed unit, internal faults are diagnosed, defective components replaced, and stored crash data professionally erased. The unit then undergoes a comprehensive functional test.

Before removing the control unit, a specialized workshop should verify whether the issue lies in external components such as sensors or wiring. If the fault is clearly within the control unit, it can be removed and sent in for repair.

Once received at Airbag24, technicians perform a detailed diagnosis to pinpoint the root cause of the problem. This may involve analyzing the circuit board, reading internal memory, or inspecting individual electronic components.

The actual restoration process depends on the nature of the defect and includes erasing crash data, replacing faulty microchips, processors, or other components, and restoring the original functionality. Each repaired control unit undergoes a final test to ensure flawless communication. We offer 2 years' statutory liability for defects on every repair.