Airbag control unit with part number A1779006704

What does the airbag control unit A1779006704 do?

The airbag control unit A1779006704 is the central control unit of the restraint system (SRS) of Mercedes-Benz. It evaluates the signals from the crash sensors, decides in a crash within milliseconds on airbags and seatbelt pretensioners, and monitors the system continuously.

The manufacturer number Bosch 0285015379 is additionally printed on the housing. The part number A1779006704 identifies the unit in the vehicle of Mercedes-Benz.

The control unit shows faults via the airbag warning light. After an accident it stores crash data and locks itself; only the repair lifts the lock.

Why does the control unit A1779006704 fail?

The most common cause is crash data stored after an accident, even if no airbag has deployed. Other causes are ageing electronic components, cold solder joints, moisture and corrosion at plug connections, and voltage spikes, for example from a weak battery or a jump start.

Crash data of this kind cannot be erased with a normal diagnostic tool. The unit keeps it until Airbag24 removes it during the repair.

Ageing components are a cause that develops over time. Cold solder joints can cause contact problems that do not fix themselves.

Moisture and corrosion at plug connections disrupt signal transmission. Voltage spikes from the vehicle electrical system put additional strain on the electronics.

How can you tell that the A1779006704 is defective?

The airbag warning light lights up permanently or intermittently, an error message appears in the instrument cluster, the diagnostic tool does not connect to the control unit, and the fault memory cannot be cleared. In such a case, airbags and seatbelt pretensioners may not trigger in an emergency.

The warning light in the instrument cluster shows the defect. It is the most important warning sign the control unit issues.

Only reading out the fault memory shows whether the defect lies in the control unit or in the wiring.

Which vehicles is the A1779006704 fitted in?

The control unit A1779006704 is fitted in these vehicles: Mercedes-Benz A-Class W177 (from 2018).

The list shows the vehicles assigned to this part number.

• Mercedes-Benz A-Class W177 (from 2018)

Please compare the part number on the label of the removed unit with this page. That only ensures you have the correct unit. Have the fault memory read out beforehand, because only the log shows whether the control unit is defective or a plug or cable is the cause.

For the same vehicles, we also repair control units with the part numbers 0 285 015 019, 0285020871, A 177 900 03 04, A1779027906, A2479013703, A2479018801.

How does the repair of the A1779006704 work?

You read out the fault memory first and enclose the log with the unit. Then you disconnect the battery, remove the control unit, create the repair order online and send in the carefully packed unit. Airbag24 typically processes the A1779006704 within 3–4 working days.

The order serves your safety. Airbag24 checks the unit on the test bench, replaces defective components, erases the stored crash data and carries out a function test. Afterwards your own unit is sent 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 A1779006704 get to Airbag24?

You send the control unit A1779006704 as a parcel or book a UPS collection for an extra charge. After the repair, Airbag24 sends the unit back to you by UPS.

Place the printed repair order in the parcel and pack the unit shock-proof.