This article provides a comprehensive overview of the diagnostic trouble code (DTC) B0086, specifically "Supplemental Deployment Loop #2 Resistance Low." This code relates to issues within the vehicle's Supplemental Restraint System (SRS), also known as the airbag system. Understanding the causes, symptoms, and potential solutions for this code is crucial for maintaining the safety and proper functioning of your vehicle's airbag system.

Comprehensive Table: B0086 Code Breakdown

| Category | Description | Possible Causes | Diagnostic Steps

Detailed Explanations

Supplemental Deployment Loop #2: Refers to a specific electrical circuit within the SRS responsible for deploying a particular airbag or component. The SRS uses multiple deployment loops for different airbags and pre-tensioners. Loop #2 is simply an identifier for one of these circuits. The specific airbag or component associated with this loop varies depending on the vehicle make and model.

Resistance Low: This indicates that the electrical resistance within the designated deployment loop is lower than the expected value programmed into the SRS control module. The SRS module monitors the resistance of each deployment loop to ensure the system is functioning correctly and to detect any faults. A lower-than-expected resistance can indicate a short circuit or a faulty component.

Possible Causes: This code can arise from various issues, including:

  • Short Circuit in Wiring: Damaged or chafed wires within the deployment loop can create a short circuit, leading to a low resistance reading. This is often the most common culprit.
  • Faulty Airbag Inflator: The airbag inflator itself could be internally shorted, causing the resistance of the loop to drop below the acceptable range.
  • Damaged Connector: Corrosion or damage to the connectors within the deployment loop can also cause incorrect resistance readings.
  • Faulty Wiring Harness: The wiring harness that connects the SRS components can be damaged, leading to shorts or low resistance.
  • SRS Control Module Malfunction: Although less common, a faulty SRS control module can misinterpret the resistance readings or incorrectly diagnose the system.
  • Incorrect Component: In rare cases, the wrong airbag inflator or other component might have been installed, resulting in an incompatible resistance value.
  • Previous Accident/Deployment: Even if the airbag didn't fully deploy, a minor impact that activated part of the SRS system can cause damage leading to this code.

Diagnostic Steps: Addressing this code requires a systematic approach to identify the root cause:

  1. Scan for Codes: Use a professional-grade scan tool to read and document all stored DTCs. Note any other SRS-related codes as they can provide valuable clues. Clear the codes and retest to see if B0086 returns.
  2. Visual Inspection: Thoroughly inspect the wiring harness, connectors, and airbag inflator associated with Deployment Loop #2. Look for signs of damage, corrosion, or loose connections. Pay particular attention to areas where the wiring harness might rub against metal or other components.
  3. Resistance Testing: Using a multimeter, measure the resistance of the deployment loop. Refer to the vehicle's service manual for the specified resistance range. Important: Disconnect the battery and wait the recommended time (usually 10-30 minutes) to discharge the SRS capacitor before performing any resistance measurements to avoid accidental airbag deployment.
  4. Component Isolation: If the resistance is outside the specified range, isolate the components within the loop (airbag inflator, wiring harness sections) to pinpoint the source of the low resistance. This involves disconnecting each component and measuring the resistance of the remaining circuit.
  5. Wiring Harness Testing: If the resistance issue is suspected to be in the wiring harness, perform a continuity test to check for shorts to ground or shorts to other wires. Also, check for proper insulation resistance.
  6. Connector Inspection/Cleaning: Clean and inspect all connectors in the loop for corrosion or damage. Use a contact cleaner specifically designed for electrical connectors.
  7. SRS Control Module Check: If all other components test within specifications, the SRS control module may be faulty. This should be diagnosed by a qualified technician using specialized diagnostic equipment.
  8. Component Replacement: Once the faulty component is identified, replace it with a new or known-good part.
  9. Code Clearing and Retest: After making repairs, clear the DTCs and retest the system to ensure the B0086 code does not return.

Frequently Asked Questions

  • What does B0086 mean? B0086 indicates a "Supplemental Deployment Loop #2 Resistance Low," meaning the electrical resistance in a specific airbag circuit is lower than expected.

  • Is it safe to drive with a B0086 code? Driving with an SRS code is not recommended. The airbag system may not function correctly in an accident, increasing the risk of injury.

  • Can I fix B0086 myself? While some visual inspections and connector cleaning can be done by a DIYer, diagnosing and repairing SRS issues often requires specialized tools and knowledge. It's best to consult a qualified technician.

  • How much does it cost to fix B0086? The cost varies depending on the cause. A simple wiring repair might be relatively inexpensive, while replacing an airbag inflator or the SRS control module can be significantly more costly. Expect to pay for diagnostic time in addition to parts and labor.

  • Will B0086 cause my airbags to deploy unexpectedly? While a low resistance might not directly cause an unintended deployment, it indicates a fault in the system that could affect its performance in an accident. Address the issue promptly.

  • What if I clear the code and it comes back? If the code returns after clearing, it means the underlying problem still exists and needs to be properly diagnosed and repaired.

Conclusion

The B0086 code indicates a potentially serious issue within your vehicle's airbag system. Proper diagnosis and repair are crucial to ensure the SRS functions correctly in the event of an accident. It is recommended to consult a qualified automotive technician experienced in SRS repairs to address this issue effectively.