Land Rover Discovery 4 airbag control unit repair

What is a Land Rover Discovery 4 airbag control unit?

The Land Rover Discovery 4 airbag control unit is the central safety unit. It activates all occupant restraint systems in the event of an accident by processing sensor data and controlling the deployment of airbags and seatbelt pretensioners. This unit, also called the Restraint Control Module (RCM), is crucial to the passive safety of your Land Rover Discovery 4.

It serves as the brain of the safety system, receiving signals from crash sensors and triggering the appropriate airbags and seatbelt pretensioners as needed. Communication takes place via special airbag connectors that ensure a secure connection.

The control unit processes 12-volt vehicle electrical system voltage. During installation or removal, safety precautions such as disconnecting the battery must be observed.

Why is the Land Rover Discovery 4 airbag control unit faulty?

The Land Rover Discovery 4 airbag control unit primarily fails after an accident, as it stores immutable crash data. Internal electronic errors or software problems can also cause failure. This manifests itself in a permanently illuminated airbag warning light and the need for a professional Land Rover Discovery 4 airbag control unit repair.

After a collision, the system stores irretrievable crash data, preventing the module from being used again without special repairs. Even without an accident, aging or voltage fluctuations can damage internal components.

Messages like "internal error" in the control unit's error log indicate a malfunction within the unit itself. Such failures require precise diagnosis and professional Land Rover Discovery 4 airbag control unit repair.

Common error codes for Land Rover Discovery 4 airbag control unit repair

When repairing the Land Rover Discovery 4 airbag control unit, specific B-codes indicate malfunctions within the Restraints Control Module (RCM). These error codes affect the airbag deployment control and the system's plausibility checks, not external sensors or seatbelt pretensioners. A precise diagnosis of these codes is crucial.

• B0020-64 → Left Side Air Bag Deployment Control - Signal plausibility failure (RCM output switched off, but airbag installed) → Signal error / Internal RCM error
• B0020-95 → Left Side Airbag Deployment Control - Incorrect assembly → Incorrect assembly / wiring
• B0021-11 → Left Curtain Deployment Control 1 - Circuit short to ground → Short circuit to ground
• B0021-12 → Left Curtain Deployment Control 1 - Circuit short to battery → Short circuit to battery
• B0021-1A → Left Curtain Deployment Control 1 - Circuit resistance below threshold → Resistance too low / Cable break
• B0028-1A → Right Side Air Bag Deployment Control - Circuit resistance below threshold → Resistance too low / Cable break
• B0028-1B → Right Side Air Bag Deployment Control - Circuit resistance above threshold → Resistance too high / Cable break
• B0028-64 → Right Side Air Bag Deployment Control - Signal plausibility failure (RCM output switched off, but airbag installed) → Signal error / Internal RCM error
• B0028-95 → Right Side Airbag Deployment Control - Incorrect assembly → Incorrect assembly / wiring
• B0029-11 → Right Curtain Deployment Control 1 - Circuit short to ground → Short circuit to ground

Additionally, general messages such as "Crash data stored" or "Internal error" in the control unit's error log may indicate internal system problems. These also require professional Land Rover Discovery 4 airbag control unit repair.

What part numbers are available for the Land Rover Discovery 4 airbag control unit repair?

Several specific OEM part numbers are relevant for Land Rover Discovery 4 airbag control unit repairs, both from Land Rover directly and from their suppliers such as Bosch and Continental. These numbers guarantee the compatibility of the replacement part with your Discovery 4 model. An exact part number match is essential for proper function.

• YWC106210 (Land Rover Original)
• HY3214D374AA (Land Rover Original)
• LR018452 (Land Rover Original)
• AH22-14D374-AG (Continental supplier)
• FK72-14D374-AF (Bosch supplier)
• NNW502432 (Continental supplier)
• Other variants (e.g. FH22 14D374 AC, FK72-14D374-AH, MK72-14D374-AD, MK72-14D374-AE, NNW502436)

These part numbers refer exclusively to the airbag control unit itself, not airbag sensors or other restraint system components. The "14D374" base is typical for different versions of the same module type.

A compatibility check by comparing the original part numbers is always recommended. This ensures proper function after a Land Rover Discovery 4 airbag control unit repair.

This is how the professional Land Rover Discovery 4 airbag control unit repair is carried out

A professional Land Rover Discovery 4 airbag control unit repair includes reading the error log, erasing crash data, or correcting internal errors, and then reprogramming the module. This process restores the airbag system to full functionality and is a cost-effective alternative to purchasing a new one.

First, a detailed diagnosis is performed using specialized tools to determine the exact cause of the defect. This includes reading all stored error codes.

After the actual repair, such as erasing crash data or repairing components, the control unit must be professionally programmed to the Land Rover's vehicle identification number (VIN). A final fault memory erase is also required.

Safety precautions, such as disconnecting the vehicle's battery before beginning work, are essential for safety during the Land Rover Discovery 4 airbag control unit repair. Only specialist workshops should perform this sensitive work.

Installation position of the Land Rover Discovery 4 airbag control unit

The Land Rover Discovery 4 airbag control unit is typically located inside the vehicle, usually centrally under the center console or in the passenger footwell. This protected location ensures the safety and integrity of the module against mechanical influences and moisture, which is important for the longevity of the unit.

The control unit is connected to yellow airbag connectors that link the module to the sensors and airbags throughout the vehicle. This distinctive color identifies safety components.

Extreme caution is required during installation and removal. Both battery cables should be disconnected, starting with the ground cable, to prevent short circuits or accidental airbag deployment.

Installation requires specialist knowledge and should only be performed by qualified personnel. This ensures the correct function of the system after the Land Rover Discovery 4 airbag control unit repair and avoids safety risks.