Airbag control unit with part number P31406534

What does the airbag control unit P31406534 do?

The airbag control unit P31406534 is the central control unit of the restraint system (SRS) of Volvo. It evaluates the signals from the crash sensors, decides in a crash within milliseconds which airbags and seatbelt pretensioners are triggered, and monitors the system continuously. After a crash it stores crash data and locks itself.

The unit reports faults in the restraint system via the airbag warning light in the instrument cluster. To do this it checks the connections to the sensors, seatbelt pretensioners and airbags, so that faults are displayed.

The evaluation runs inside the unit itself. The sensor signals are bundled there, checked and translated into triggering commands, which must be carried out without delay in an emergency.

Why does the control unit P31406534 fail?

Most often the fault is caused by stored crash data, even if no airbag has deployed. A standard diagnostic tool cannot erase this data. Other causes are aged electronic components, cold solder joints, moisture and corrosion at plug connections, and voltage spikes.

After a crash the crash data stays in memory, even if the airbags remained untriggered. A conventional diagnostic tool cannot reach it, which is exactly why the fault persists.

The electronics in the unit age like any other electronics. Solder joints on the circuit board can go cold over time, and moisture or corrosion at the plug connections disturbs the contact. Voltage spikes also affect the unit; a weak battery or an improperly carried out jump start can cause them.

How can you tell that the P31406534 is defective?

The airbag warning light in the instrument cluster lights up permanently or intermittently, a fault message appears in the instrument cluster, the diagnostic tool finds no connection to the control unit, and the fault memory cannot be cleared. In an emergency, airbags and seatbelt pretensioners may then fail to trigger.

The airbag warning light in the instrument cluster is the most important warning sign. It is either on continuously or flickers intermittently, and in both cases it must be taken seriously.

A fault message in the instrument cluster accompanies it. If the diagnostic tool cannot connect to the control unit, or the fault memory cannot be cleared, this also points to a problem. The system no longer confirms its own function.

Which vehicles is the P31406534 fitted in?

The P31406534 is fitted in these vehicles: Volvo V40 Serie 2 (2012-2016).

The vehicles in which this control unit was fitted are listed here:

• Volvo V40 Serie 2 (2012-2016)

Before you create a repair order, two checks help. Compare the part number on the label of the removed unit with this page, and you can be sure it is the right unit. Also have the fault memory read out, because only this result shows whether the control unit is defective or whether a plug or cable is the cause.

For the same vehicles, we also repair control units with the part numbers 285001147, 30611294, 30612702D, P31406938, P31429510.

How does the repair of the P31406534 work?

First have the fault memory read out and attach the log. Then disconnect the battery and only then remove the control unit. Next, create a repair order online and send the unit in, well packed. Airbag24 tests, repairs and checks the unit, after which your own unit is returned.

The fault memory reflects the state of the fault search, which is why the log belongs with the order. Disconnecting the battery is a safety step that must be completed before removal.

At Airbag24 the unit is examined on the test bench, defective components are replaced, stored crash data is erased and a function test is carried out. Processing 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 P31406534 get to Airbag24?

You send the unit as a parcel or book a UPS collection for an extra charge. After the repair, Airbag24 returns the unit to you by UPS.

Put the printed repair order into the parcel and pack the control unit shock-proof, so that it is not damaged on the way.