Airbag control unit with part number 3SR820

What does the airbag control unit 3SR820 do?

The airbag control unit 3SR820 is the central control unit of the SRS restraint system in vehicles of Mitsubishi. It evaluates the signals from the crash sensors, decides in an accident within milliseconds on airbags and seatbelt pretensioners, and monitors the system continuously. It reports faults via the airbag warning light.

During driving, the unit keeps working unobtrusively and continuously checks the system's components. After an accident it stores crash data and locks itself.

Why does the control unit 3SR820 fail?

Stored crash data is the most frequent cause after an accident, even if no airbag was triggered; a standard diagnostic tool cannot erase it. Aged electronic components, cold solder joints, moisture and corrosion at connectors, and voltage spikes from weak batteries or jump-starting also come into play.

Crash data stays stored in the unit even if the car continues to drive normally afterwards. It is therefore regularly the first point the fault-finding checks.

The other causes lie in the electronics. Components age, solder joints can go cold, and moisture or corrosion impair the connectors.

How can you tell that the 3SR820 is defective?

The airbag warning light in the instrument cluster stays on permanently or intermittently, and an error message appears in the instrument cluster. In addition, the diagnostic tool does not connect to the control unit, and the fault memory cannot be cleared.

The warning light shows the defect, and in an emergency airbags and seatbelt pretensioners may not deploy. Therefore have such signs checked promptly.

Which vehicles is the 3SR820 fitted in?

The control unit 3SR820 is fitted in these vehicles: Mitsubishi Space Star A00 1st Facelift (2016-2019), A00 (2012-2016) and A00 2nd Facelift (from 2019). Compare the details in this section to see whether your car belongs to them.

The vehicles for this part number are shown in the following list.

• Mitsubishi Space Star A00 1st Facelift (2016-2019)
• Mitsubishi Space Star A00 (2012-2016)
• Mitsubishi Space Star A00 2nd Facelift (from 2019)

Compare the part number on the label of the removed unit with this page, and you know you have the right unit; the cause, however, is not revealed by this. Therefore have the fault memory read out beforehand. Only this result shows whether the control unit itself is defective or a connector or a cable is the cause.

For the same vehicles, we also repair control units with the part numbers 8635A234, 8635A374, 8635A377, 8635A393, 8635A396, 8635A409.

How does the repair of the 3SR820 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. At Airbag24, testing, repair and function test together take 3–4 working days as a rule.

Airbag24 checks the submitted unit on the test bench and replaces defective components. Airbag24 then deletes the stored crash data and carries out a function test before your own unit is returned.

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 3SR820 get to Airbag24?

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

Enclose the printed repair order and pack the control unit shock-proof.