The Bmw 93b2 Code indicates a problem with the Battery Safety Terminal (BST) detonation signal circuit. This article provides a detailed guide to understanding and resolving this issue, specifically focusing on replacing the faulty wiring without replacing the BST itself. This process is possible even on older BMW models, such as a 2006 330i.
Identifying the Problem Area
The 93B2 code often stems from the short detonation signal wire connecting the airbag wiring to the BST. While the BST itself is often blamed, the problem often lies within this small, removable wire. Intermittent code appearances, influenced by wire positioning, often point to this culprit.
The Solution: Replacing the Detonation Signal Wire
Replacing this wire, even on older BST models with a seemingly sealed black plastic casing, is the most effective solution. While the casing might look impenetrable, the section housing the signal wiring is made of flexible plastic that can be carefully manipulated.
Acquiring the Replacement Part
BMW part dealers offer a replacement wire under part number 61129130178. While significantly longer than the original (approximately 20 feet), it comes with the correct metal connectors for the BST side.
Detailed Replacement Instructions:
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Preparation: Disconnect the battery and unbolt the BST’s battery cable for easier access.
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Disconnecting the Old Wire: Using nose pliers, carefully twist and bend the flexible plastic portion of the BST casing near the signal wire entry point. This creates enough space to disconnect the old wire’s plug, which is a 90-degree airbag connector requiring an upward pull. Note: Locking tabs on the plug might break during removal.
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Connecting the New Wire: Insert the new wire’s plug into the BST and ensure it clicks into place. Gently bend the plastic casing back to its original position.
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Adapting the Takata Connector: Disassemble the black/yellow Takata connector on the other end of the old wire. Carefully remove the wires, noting the position of each wire (using tape to mark pin 1 is recommended). Insert the new wire’s pins into the Takata connector housing, ensuring a secure connection. Reassemble the connector.
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Managing Excess Wire Length: The new wire is considerably longer than needed. While soldering and shortening is ideal, carefully bundling and securing the excess wire alongside the battery is a viable alternative.
- Final Steps: Reinstall the BST, reconnect the battery, and reset the airbag module.
Understanding the Underlying Cause
The old wire often develops hairline fractures or internal corrosion, leading to increased and fluctuating resistance (over 1 ohm in a 6-inch wire). This erratic resistance triggers the 93B2 code.
Conclusion
Replacing the BST detonation signal wire is a practical and effective solution for the BMW 93B2 code. While the process requires careful manipulation of the BST casing, it eliminates the need for a costly BST replacement. Following these instructions can resolve the issue and prevent future occurrences of the error code.
