Airbag control unit with part number KD35-57K30B

What does the airbag control unit KD35-57K30B do?

The airbag control unit KD35-57K30B is the switching hub of the restraint system (SRS) in Mazda vehicles. It evaluates the signals from the crash sensors, decides in an impact within milliseconds whether airbags and seatbelt pretensioners are triggered, and monitors the system continuously. It shows faults found via the airbag warning light.

Monitoring covers the firing circuits, sensor connections and the supply voltage, and runs throughout operation.

After an accident, the control unit stores crash data and locks itself. The data remains stored in the unit.

Why does the control unit KD35-57K30B fail?

Stored crash data is the most common cause with the KD35-57K30B, even if no airbag was triggered. Other causes are ageing electronic components, cold solder joints, moisture and corrosion at plug connectors, and voltage spikes, for example from a weak battery or a jump start.

A standard diagnostic tool cannot erase crash data. Airbag24 removes it during the repair.

The remaining causes lie in the electronics. Components on the circuit board age over time, and solder joints can go cold.

Moisture and corrosion impair the contact at plug connectors, and voltage spikes put additional strain on the circuit.

How can you tell that the KD35-57K30B is defective?

The airbag warning light in the instrument cluster lights up permanently or intermittently. In addition, a fault message may appear, 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 light is the first sign that something in the system is wrong. If it does not go out after switching on the ignition, have the system checked.

Which vehicles is the KD35-57K30B fitted in?

The control unit KD35-57K30B is fitted in these vehicles: Mazda CX-5 KE (2011-2015) and KE Facelift (2015-2017).

Here you will find the vehicles to which Airbag24 assigns this control unit.

• Mazda CX-5 KE (2011-2015)
• Mazda CX-5 KE Facelift (2015-2017)

Compare the part number on the label of the removed unit with this page; this only ensures that it is the right unit. Whether the control unit is defective or a plug or cable is the cause is shown only by the fault memory read out beforehand.

For the same vehicles, we also repair control units with the part numbers KA1C-57-K30A, KA1C-57K30, KD45-57K30B, KEAD 57K30 C, KR2757K30A.

How does the repair of the KD35-57K30B work?

For the KD35-57K30B, first have the fault memory read out and attach the log. Then disconnect the battery and only afterwards remove the control unit. Next, create a repair order online and send the unit in well packed. Testing, repairing and function-testing at Airbag24 usually take 3–4 working days.

Airbag24 checks the unit on the test bench, replaces defective components, deletes stored crash data and carries out a function test. Afterwards, 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 KD35-57K30B get to Airbag24?

You send the KD35-57K30B to Airbag24 as a parcel or book a UPS collection for an extra charge. After the repair, Airbag24 returns it to you by UPS.

Put the printed repair order in the parcel and pack the unit shockproof.