Fix B0020: Mechanic’s Solutions That WORKED!

The B0020: Side Airbag Deployment Control Circuit Open means an issue within the side airbag deployment control circuit, specifically signaling an open circuit condition.

This code can surface after a vehicle has been involved in an accident and repaired, or if there’s a fault in the airbag’s electrical connections. Essentially, it means the system designed to protect passengers by deploying side airbags in a crash might not function correctly due to a break or disconnection in the circuit.

B0020 quick overview

Meaning	B0020: Side Airbag Deployment Control Circuit Open
Is it serious?	Yes, this code is critical because it affects the airbag system, compromising passenger safety in a collision.
Possible causes	– Faulty wiring or connectors – Damaged airbag sensors – Faulty side airbag module – Corrosion or poor connections under seats
How to diagnose?	Inspect wiring and connectors for damage or looseness. Check airbag sensors and modules for faults. Monitor B0020 PIDS using a diagnostic scanner to pinpoint issues. Use a 2-ohm resistor to test circuit integrity. Reflash the SRS module if updates or corrections are necessary.

How to fix B0020 – learn from mechanics

I looked into B0020 service cases at iatn.com website where in the private forums the mechanics seek advice from other mechanics. I looked up a bunch of cases to help you decide how to fix your issue and see what would a real mechanic do to solve it.

Case #1: Mercury B0020

Vehicle information 2010 Mercury Milan Premier 2.5L

Issue + repair history

• Code for left side airbag deployment control circuit open (B0020-13) detected.
• Vehicle previously involved in an accident and repaired.
• Symptoms include airbag light illumination.

Other OBD2 Codes + Test Results

• Test for codes: B0020
• Ohm left impact sensor: Test good
• Replaced left sensor: No change
• Inspected wiring: Seems okay

Mechanic suggestions

• Access PIDS for SRS module and monitor all B0020 PIDS to pinpoint the system or circuit issue.
• Check the airbag itself for an open circuit or consider the possibility of a faulty clockspring.
• Verify the integrity of airbag connections under the driver’s seat, ensuring no corrosion or broken wires.
• Use a 2 ohm resistor as a dummy load on the circuit to simulate the airbag and test if the code disappears.
• Ensure proper installation of the airbag and seat, as amateur repairs may lead to open circuits.
• Reflash the SRS module if necessary, considering any relevant TSBs on the SRS system.

Final fix

• Fixed the issue by addressing loose wires under the driver’s seat, which resolved the open circuit fault.

Case #2: Chevrolet B0020

Vehicle information 2008 Chevrolet Cobalt LT 2.2L

Issue + repair history

• Codes: P0019, B0020-04 (passenger frontal deployment loop stage 2 open circuit).
• No flow charts available for repair/diagnosis.
• Identified broken wire at the connector for the passenger dash airbag.
• Wire repair resolved the issue.

Other OBD2 Codes + Test Results

• No additional OBD2 codes mentioned.

Mechanic suggestions

• Use special tools from the dealer to duplicate components for diagnosis.
• Check the right front seat belt retractor and wire harness for chafing and cut wires.
• Verify wiring integrity to the airbag and inspect for any damage or loose connections.
• Consider checking the clock spring and airbag connectors.

Final fix

• Repaired the broken wire at the connector for the passenger dash airbag, resolving the open circuit fault.

Case #3: Toyota B0020

Vehicle information 2014 Toyota Corolla LE 1.8L

Issue + repair history

• Error code: B0020-12 (passenger frontal deployment loop stage 2 open circuit).
• No prior repair history mentioned.
• Seeking guidance on diagnosis and repair.

Other OBD2 Codes + Test Results

• No additional OBD2 codes provided.
• No specific test results mentioned.

Mechanic suggestions

• Inspect the passenger side airbag system for any visible damage or loose connections.
• Check the wiring harness leading to the passenger side airbag for signs of wear, abrasion, or breaks.
• Use a multimeter to test the continuity of the wiring circuit and the integrity of the connectors.
• If no visible issues are found, consider replacing the passenger side airbag module.

Final fix

• Identified a loose connector at the passenger side airbag module.
• Reconnected the loose connector, resolving the open circuit fault.

Diagnostic Step	Explanation
Inspect wiring and connectors under the seats	Look for any signs of damage, looseness, or corrosion that could interrupt the circuit.
Check the airbag sensors and modules	Ensure these components are functioning properly and are not the source of the open circuit.
Monitor B0020 PIDS with diagnostic scanner	Use specialized tools to observe real-time data and pinpoint the fault in the system.
Use a 2 ohm resistor to simulate the airbag	This test helps determine if the rest of the circuit is intact by replacing the airbag with a resistor.
Reflash the SRS module	Update or correct the module’s software based on technical service bulletins or known issues.
Repair or replace broken wires and connectors	Address any physical damage found during the diagnostic process to restore circuit continuity.

By addressing these steps, drawn from real-life service cases, technicians can effectively troubleshoot and resolve the issues leading to the B0020 code. Given the safety implications, it’s important for vehicle owners to address this code promptly with the help of a professional to ensure the airbag system is fully operational.

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