Airbag control unit with part number 28556-3AP1B

What does the airbag control unit 28556-3AP1B do?

The airbag control unit 28556-3AP1B manages the restraint system (SRS) at Nissan and decides in a crash which airbags and seatbelt pretensioners trigger. To do this it evaluates the signals of the crash sensors, within milliseconds. After an accident it stores crash data and locks itself.

Between journeys the unit continuously checks its activation and the connected components. If it detects a fault, it displays it via the airbag warning light and records it in the fault memory.

Why does the control unit 28556-3AP1B fail?

On the 28556-3AP1B, stored crash data from an accident is the most common cause, even if no airbag has deployed. A diagnostic tool from the trade cannot erase it. Besides that, ageing of the electronics, cold solder joints, moisture and corrosion at plug connections and voltage spikes, for example from a weak battery, come into question.

The crash data therefore stays in the unit after the accident until the repair removes it.

The other causes are hardly noticeable. Solder joints on the circuit board loosen over time, moisture corrodes contacts, and current surges when starting stress the electronics.

How can you tell that the 28556-3AP1B is defective?

On the 28556-3AP1B, a defect mainly shows up through the airbag warning light, which lights up permanently or intermittently. A fault message in the instrument cluster may accompany it. In an emergency, airbags and seatbelt pretensioners may possibly fail to trigger.

Even if the diagnostic tool cannot establish a connection, or the fault memory cannot be cleared, a suspicion is justified. Have such findings clarified promptly.

Which vehicles is the 28556-3AP1B fitted in?

The control unit with the number 28556-3AP1B is intended for Nissan vehicles. The assignment so far names only this vehicle: Nissan Almera N17 (2011-2020).

The list below records this assignment, so you can compare it directly with your vehicle.

• Nissan Almera N17 (2011-2020)

Both steps help with the comparison. Comparing the part number on the label of the removed unit with this page only confirms the identity of the unit. Reading out the fault memory before you remove anything shows whether the control unit itself is defective or whether a plug or cable is the cause.

For the same vehicles, we also repair control units with the part numbers 28556-9KN1B, 98820-9KA0A.

How does the repair of the 28556-3AP1B work?

First read out the fault memory and enclose the log, then disconnect the battery and only then remove the 28556-3AP1B. Afterwards create a repair order online and pack the unit well for shipping.

On the test bench, Airbag24 examines the unit, repairs defective components, erases the stored crash data and carries out a function test. Processing at Airbag24 usually takes 3–4 working days.

Our repairs come with 2 years' statutory liability for defects.

The repaired control unit comes back with all vehicle data and is ready for use as soon as it is refitted — no coding or programming is required.

How does the control unit 28556-3AP1B get to Airbag24?

You can send the 28556-3AP1B as a parcel or book a UPS collection for an extra charge. After the repair, the unit goes back to you via UPS.

Put your printed repair order in the parcel, and pack the unit shock-proof.