Technical Meaning
Code B0001 indicates an anomaly in the Stage 1 deployment circuit of the driver’s front airbag. The RCM (Restraint Control Module) detects:
| Sub-code | Fault | Explanation |
|---|---|---|
| B0001:11 | Short to ground | Contact between the circuit and the body/chassis |
| B0001:12 | Short to battery | Contact with a +12V circuit |
| B0001:13 | Open circuit | Cut wires, disconnected connector, or infinite resistance |
| B0001:1A | Resistance too low | Value < minimum threshold (e.g., < 1.5 Ω) |
Detection Mechanism:
The RCM continuously measures the resistance of the airbag loop (normal value: 1.8 – 3.5 Ω). A deviation triggers the code. Cross-coupling (short circuit between airbag circuits) also generates this code + other associated DTCs.
Symptoms
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🔴 Airbag warning light on (mandatory)
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⚠️ “Service Airbag” or “Restraint System Faulty” message
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🛑 Driver airbag inoperative (confirmed by SRS scan tool)
Probable Causes (Order of Frequency)
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Faulty clockspring (60-70% of cases):
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Damaged connection spiral in the steering column (wear, improper steering wheel handling).
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Connection issues:
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Connector under driver’s seat: oxidation, bent pins, broken lock.
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RCM connector: corrosion or moisture (module often under front carpet).
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Damaged wiring:
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Chafed/pinched wires under the seat or steering column.
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Short circuit due to rodents, water, or electrical modifications.
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Driver airbag faulty (rare except after impact/flooding).
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RCM failure (very rare: check last).
Diagnostic Procedure (⚠️ ABSOLUTE SAFETY)
Prerequisites:
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Disconnect the battery (- then +).
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Wait 15 minutes (dissipation of residual energy from capacitors).
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Equipment: Insulating gloves, safety glasses, multimeter, SRS scan tool.
Step 1: Visual Inspection (Key Areas)
| Location | Points to Check |
|---|---|
| Under driver’s seat | Yellow airbag connector: corrosion, deformed pins, broken clip. |
| Steering column | Clockspring: exposed wires, noises when turning, misaligned steering wheel. |
| Wiring route | Crushed/chafing wires between seat and RCM (door/sill passage). |
| RCM connectors | Moisture/corrosion (remove carpet if necessary). |
→ If problem found: Clean connectors with electrical contact spray without disassembling SRS components.
Step 2: Electrical Tests (Multimeter)
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Disconnect the airbag (yellow connector under seat).
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Measure airbag resistance:
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Normal range: 1.8 – 3.5 Ω (out of range = airbag faulty).
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Test the clockspring:
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Disconnect at both ends (steering wheel and column base).
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Check:
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Continuity between corresponding pins (< 1 Ω).
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No short circuit between circuits or to ground.
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Check wiring RCM → airbag:
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Continuity between RCM pins and airbag connector (< 1 Ω).
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Insulation: No continuity between circuits or to ground/battery.
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Step 3: Advanced Diagnosis (SRS Tool)
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Read precise sub-codes (e.g., B0001:13 = open circuit).
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Measure loop resistance via the tool:
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Expected value: 2.0 – 3.0 Ω (varies by manufacturer).
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Force a loop test if function available.
Repair
| Fault | Solution | Precautions |
|---|---|---|
| Faulty clockspring | Replace + center the steering wheel before removal. | Do not turn the steering wheel once clockspring is removed. |
| Corroded connector | Clean or replace the housing. | Use SRS certified connectors (yellow). |
| Damaged wiring | Repair with 0.35–0.5 mm² wires, heat-shrink tubing. | Avoid sharp angles, add anti-chafing protection. |
| Faulty airbag | Replace the unit. | ⚠️ Never reuse a deployed/faulty airbag. |
| Faulty RCM | Replace + reprogram. | Check for absence of short circuit before installation. |
After Repair
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Reconnect the battery (first + then –).
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Clear codes with an SRS tool (standard OBD2 insufficient).
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Verify that the airbag warning light turns off at startup.
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Perform a full system test via the tool.
🔴 Critical Warning:
Never test the airbag with a voltage source (risk of deployment).
If you are not equipped/trained, entrust the repair to an authorized workshop. An error can cause a fatal failure or unintended deployment.
Reference document: Always consult the vehicle’s workshop manual (procedures and specific values vary by brand).