Airbag control unit with part number 32221578

What does the airbag control unit 32221578 do?

The unit controls the restraint system (SRS) in Volvo vehicles. It monitors the crash sensors, decides within milliseconds in a crash which airbags and seatbelt pretensioners are triggered, and reports faults via the airbag warning light. After an accident it stores crash data and locks itself.

Monitoring runs throughout operation. During this the control unit checks whether sensors, wiring and firing circuits deliver plausible values.

Crash data document what the sensors registered around an event. They remain in the unit's memory.

Why does the control unit 32221578 fail?

The most common cause is crash data stored after an accident, even if no airbag has deployed; a usual diagnostic tool cannot remove them. Other causes are aged components, cold solder joints, moisture and corrosion on connectors, and voltage spikes.

The entry is tied to the event, not to an airbag deploying. That is why crash data can remain in memory after an incident in which no airbag reacted.

The other points concern the electronics over time and the environment of the connectors. The individual causes include:

• aged electronic components
• cold solder joints
• moisture and corrosion on connectors
• voltage spikes, for example from a weak battery or jump-starting

How can you tell that the 32221578 is defective?

A fault shows when the airbag warning light in the instrument cluster lights up permanently or intermittently, an error message appears, the diagnostic tool cannot make contact with the control unit, or the fault memory cannot be cleared. In an emergency, the airbags and seatbelt pretensioners may then fail to trigger.

The individual signs:

• Airbag warning light lights up permanently or intermittently
• Error message in the instrument cluster
• No connection between diagnostic tool and control unit
• Fault memory cannot be cleared

One sign alone does not prove which component is affected. That requires reading out the fault memory.

Which vehicles is the 32221578 fitted in?

The control unit 32221578 is fitted in these vehicles: Volvo V40 Serie 2 Facelift (2016-2019) and Serie 2 (2012-2016).

The following vehicles are stored for this part number:

• Volvo V40 Serie 2 Facelift (2016-2019)
• Volvo V40 Serie 2 (2012-2016)

Compare the part number on the label of the removed unit with this page. That only establishes that it is the right unit. Have the fault memory read out beforehand, because only that shows whether the control unit is defective or a connector or cable is the cause.

For the same vehicles, we also repair control units with the part numbers P31350547, P31387534, P31406254, P31406534, P31406631, P31406938.

How does the repair of the 32221578 work?

First you have the fault memory read out and attach the log, then disconnect the battery and only then remove the control unit. Next create the repair order online and send the unit in well packed. At Airbag24 processing usually takes 3–4 working days.

Airbag24 checks the unit on the test bench, repairs defective components, erases stored crash data and carries out a function test. Only then is the unit sent back.

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 32221578 get to Airbag24?

You send your unit in as a parcel, or you book a UPS collection for an extra charge. After the repair Airbag24 sends it back to you by UPS.

The printed repair order belongs in the parcel, and the unit must be packed shock-resistant.