Peugeot 306 Break I airbag control unit repair

What is a Peugeot 306 Break I airbag control unit?

The Peugeot 306 Break I airbag control unit is the central control unit of the restraint system (SRS). It monitors the system on every journey, decides within milliseconds in an accident whether to deploy airbags and seatbelt pretensioners, and reports faults via the airbag warning light.

When the ignition is switched on, the control unit runs a self-test; the airbag warning light comes on briefly and goes out if everything is in order. After that it continuously checks the firing circuits, the power supply and the connection to the sensors in the background. The control unit is fitted in the Peugeot 306 Break I in the 1994 to 2002 model series and comes from Autoliv.

In a collision it evaluates the signals from the crash sensors and deploys the appropriate airbags and seatbelt pretensioners. After an accident it stores crash data and locks itself.

Why is the Peugeot 306 Break I airbag control unit defective?

The most common cause is crash data stored after an accident, even if no airbag deployed. Other causes are aged electronic components, cold solder joints, moisture and corrosion on connectors, and voltage spikes.

The stored crash data cannot be erased with an ordinary diagnostic tool. The control unit then stays in a fault state, even if nothing is visible on the outside of the Peugeot 306 Break I. In addition, electronic components age over the years, solder joints can become cold and cracked, and moisture and corrosion on the connectors can lead to contact resistance. Voltage spikes, for example from a weak battery or a jump start, can also damage the electronics.

Typical signs are a permanently lit airbag warning light, a fault memory that cannot be cleared, or a diagnostic tool that cannot connect to the control unit.

Common error codes for Peugeot 306 Break I airbag control unit repair

The error codes for the Peugeot 306 Break I airbag control unit relate to internal control unit faults, communication, the power supply and the firing circuits of the airbags. Each code describes the area in which the system has detected a fault.

In practice, you may come across these codes on this vehicle, among others:

• B1000 → Internal control unit fault
• B1001 → Internal fault, airbags are deactivated
• B1004 → Internal airbag control unit fault
• U0151 → Communication with the control unit lost
• 9650 → Supply voltage fault
• A601 → Driver airbag stage one firing circuit, short to positive
• A603 → Passenger airbag stage one firing circuit, short to positive

Error codes are read out with a diagnostic tool. A code alone does not reliably show that the control unit is defective: connectors, wiring or an airbag module can also be the cause. Only an inspection will clarify where the fault actually lies.

What part numbers are available for the Peugeot 306 Break I airbag control unit repair?

The part number is printed on the label of the control unit and determines the exact version. Within the model series there are different numbers depending on equipment and year of manufacture.

Here you will find known part numbers for the Peugeot 306 Break I; the list makes no claim to completeness.

• 9633504080 (Autoliv)
• 9633621280 (Autoliv)
• 9636894180 (Autoliv)
• 9637547280 (Autoliv)
• 9643825880 (Autoliv)

Compare the number on your unit with this list. This only ensures that it is the right unit. Whether it is defective is only shown by reading out the fault memory or by the inspection.

This is how you get to the repair: have the fault memory read out, disconnect the battery and remove the control unit. Then create a repair order online and send in the unit. Processing at Airbag24, including inspection, repair and testing, usually takes 3–4 working days. 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.