Airbag control unit with part number 89170-B2A90

What is the function of the airbag control unit 89170-B2A90?

The airbag control unit with part number 89170-B2A90 is the central control unit (SRS Control Unit) for the passive safety system in Daihatsu vehicles. It is specifically designed for the Daihatsu Tanto L375 and Tanto Exe L465 models and is responsible for monitoring the entire restraint system and activating it in the event of a crash.

This component continuously processes data from various crash sensors distributed throughout the vehicle. Based on this information, the control unit determines within milliseconds whether a collision has occurred and which restraint devices—such as the driver’s airbag, knee airbag, or seatbelt pretensioners—need to be deployed to provide optimal protection for occupants.

As the “brain” of the Supplemental Restraint System (SRS), the device ensures that all components of the safety system work together seamlessly. Therefore, its proper functioning is essential for vehicle passive safety.

Why does the control unit 89170-B2A90 fail?

The most common causes of failure for the control unit 89170-B2A90 are stored crash data following an accident, which can lock the unit, as well as electronic defects in internal components. These issues may result in complete failure under heat or communication problems. External wiring faults are also a potential cause.

A very common reason for a perceived malfunction is stored crash data. After a collision in which airbags or seatbelt pretensioners have been deployed, the control unit locks itself for safety reasons.

Another typical defect is an internal hardware failure, often manifesting as complete shutdown when the unit heats up. Communication with diagnostic equipment may also be lost, complicating troubleshooting. The root cause is usually defective electronic components on the circuit board.

Peripheral issues, such as broken wires or faulty connectors to the SRS system, can also falsely suggest a problem with the control unit. These symptoms appear identically across comparable Toyota and Daihatsu part numbers like 89170-0D100 and 89170-02A90.

How do you recognize a fault in the 89170-B2A90?

A fault in the control unit 89170-B2A90 primarily manifests as a permanently illuminated airbag warning light (SRS lamp) in the instrument cluster. Additional symptoms include heat-related complete failure—where even the clock stops working—or inability to establish communication with a diagnostic tool.

The most obvious sign is the active airbag warning light that fails to turn off after starting the engine. This indicates a fault in the restraint system and its deactivation, posing a significant safety risk in the event of a crash.

A specific symptom is heat-induced failure: as the interior temperature rises, the control unit shuts down completely, often affecting other functions like the clock. In this state, communication via the diagnostic interface becomes impossible.

Even after a minor accident, a lit SRS lamp clearly signals stored crash data within the control unit. The system remains locked.

In which vehicles is the control unit 89170-B2A90 installed?

The airbag control unit with part number 89170-B2A90 is specifically used in Daihatsu vehicles. It is primarily assigned to the Tanto L375 models from 2007 to 2013, as well as the related Tanto Exe L465 model. This assignment has been technically verified.

At Airbag24, repairs for the control unit with part number 89170-B2A90 are offered for the following models:

Daihatsu: Tanto L375 (2007–2013), Tanto Exe L465

The technical issues and repair methods are similar to those of comparable control units from Toyota and Daihatsu, such as part numbers 89170-0D100, 89170-02A90, or 89170-47390, found in models like the Toyota Aygo AB10 or Previa. For the Daihatsu Tanto L375, the alternative OEM replacement part number 89170-B2830 is also relevant.

What are the advantages of repairing 89170-B2A90?

The biggest advantage of repair is substantial cost savings compared to purchasing an expensive new part directly from the manufacturer. Additionally, the original vehicle configuration is preserved, eliminating the need for time-consuming coding or reprogramming. The repair restores full functionality to the safety system.

Repair represents an economically sensible alternative to buying a new unit, since often only individual electronic components need to be replaced. This approach is significantly cheaper than acquiring a completely new device.

Unlike used control units of unclear origin, which may already have their own defects or not last long, a professional repair offers peace of mind. 2 years’ statutory liability for defects is provided on all work performed, underscoring the quality and durability of the repair.

How does the repair process at Airbag24 work?

The repair process at Airbag24 is standardized and transparent. After removing and sending in the defective control unit 89170-B2A90, a precise diagnosis is carried out. This is followed by expert repair, which may include replacing components, culminating in a final functional test. With this control unit, erasing the crash data is often not possible. If the crash data needs to be erased, please contact us briefly before sending the unit in – we will check your part number.

Once the device has been securely packaged and received at Airbag24 along with the completed repair form, it undergoes a detailed analysis. Specialized diagnostic tools read the internal fault memory to pinpoint the exact cause of the defect—whether it’s stored crash data or a hardware issue.

Based on the diagnosis, the necessary repairs are performed. This could involve replacing faulty electronic components on the circuit board. Each repair is executed precisely according to the manufacturer’s specifications.

Finally, every repaired control unit undergoes a thorough functional test and calibration to ensure full operability of the SRS system. All repairs come with 2 years' statutory liability for defects.