Airbag control unit with part number 28556 2X21A

What does the airbag control unit 28556 2X21A do?

The airbag control unit 28556 2X21A is the central control unit of the restraint system for Nissan. It evaluates the crash sensors, decides in an accident whether airbags and seatbelt pretensioners are triggered, and monitors the system continuously.

It reports faults via the airbag warning light in the instrument cluster. After an accident it stores crash data and locks itself.

Seatbelt pretensioners and airbags are therefore controlled by a single unit.

Why does the control unit 28556 2X21A fail?

The most common cause is crash data stored after an accident, even without an airbag deployment. Ageing components, cold solder joints, moisture and corrosion, and voltage spikes are also possible.

The crash data stays in the unit after the accident. A normal diagnostic tool cannot remove it; during the repair Airbag24 erases it.

Further causes at a glance:

• ageing electronic components
• cold solder joints
• moisture and corrosion at plug connections
• voltage spikes, for example from a weak battery or a jump start

How can you tell that the 28556 2X21A is defective?

An airbag warning light that stays on permanently or intermittently can indicate a defect in the 28556 2X21A. Fault messages, a diagnostic tool without connection and a fault memory that cannot be cleared may also appear.

With the light, the unit itself reports that something is wrong in the restraint system. In an emergency, airbags and seatbelt pretensioners may then fail to trigger. If the warning light stays on permanently, have the vehicle checked promptly.

Which vehicles is the 28556 2X21A fitted in?

The 28556 2X21A is fitted in these vehicles: Nissan Terrano R20 (1993-2007).

These vehicles are assigned to the unit:

• Nissan Terrano R20 (1993-2007)

Comparing the part number on the label with this page confirms only that you have the correct unit. Whether the control unit itself is defective, or whether a plug or a cable is the cause, is shown by the fault memory, which you should have read out before removal.

For the same vehicles, we also repair control units with the part numbers 285001109, 285001480, 28556 8F000, 285562X100, 285562X11C, 988202X325.

How does the repair of the 28556 2X21A work?

Have the fault memory read out and attach the log before you disconnect the battery. Then remove the 28556 2X21A, create a repair order online and send in the unit, well packed.

On the test bench Airbag24 examines the unit that has arrived, finds defective components and repairs them, erases the stored crash data and carries out a functional test. Processing usually takes 3–4 working days. After that your own unit goes back to you.

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 2X21A get to Airbag24?

You send the control unit 28556 2X21A to Airbag24 as a parcel, or you book a UPS collection for an extra charge. After the repair the unit comes back to you by UPS.

The printed repair order is enclosed in the parcel, and the unit is packed shockproof.