Code
B1B2A
MITSUBISHI
B — Body
DR.belt pretensioner circuit OPN
Views:
UK: 9
EN: 17
RU: 12
AI status
Completed
Completed
100%
Causes
- Open circuit in driver pretensioner wiring
- Disconnected or poorly seated connector at pretensioner or SRS unit
- Corroded or damaged connector terminals
- Broken wire due to seat movement or previous repairs
- Failed pretensioner squib (open internal coil)
- Faulty SRS (airbag) control module or connector
Symptoms
- SRS / airbag warning lamp illuminated
- Stored B1B2A code (may be accompanied by other SRS codes)
- Seat belt pretensioner will not fire in a crash until repaired/replaced
- Possible intermittent SRS warning if connector/wire intermittent
What to check
- Use an OBD-II/SRS-capable scan tool to read freeze-frame and stored SRS codes
- Visually inspect driver seat area, pretensioner connector and wiring for damage, corrosion, or disconnection
- Check for signs of prior deployment (deployed pretensioner or airbag components)
- Confirm SRS warning lamp behavior (on with key on, self-check sequence)
- Follow manufacturer safety procedure: disable SRS power (disconnect battery and wait specified time) before disconnecting pretensioner connectors or measuring continuity
Signal parameters
- Expected pretensioner coil resistance (varies by model): typically low ohms (example range ~0.5–3 Ω). Open = infinite/OL
- At rest, no deployment voltage should be present across squib; deployment is a short high-current pulse from SRS unit
- Open-circuit detection: continuity check returns OL/infinite between pretensioner terminals or between pretensioner and SRS module
- Module may report dwell/diagnostic voltage pulses during self-test — use a qualified SRS scan tool to view
Diagnostic algorithm
- Read and record all SRS codes and freeze-frame data with a compatible scan tool. Note any accompanying codes.
- Verify vehicle battery state and follow manufacturer SRS power-down procedure (disconnect battery negative and wait the specified time, commonly 90 seconds or more) before working on SRS components.
- Perform a careful visual inspection of the driver pretensioner connector, pigtail, and wiring routing under/around the seat. Look for chafing, pin damage, bent pins, corrosion, or water intrusion.
- With SRS power safely disabled, disconnect the pretensioner connector and check continuity/resistance across the pretensioner terminals. An open reading (OL/infinite) indicates an open squib or open wiring. Compare measured resistance to the model’s specification.
- Check continuity from the pretensioner connector back to the SRS control module connector pins to locate an open in the harness. Repair any open, chafe or broken sections found.
- Inspect and clean connectors; repair or replace corroded connectors or damaged terminals. Ensure proper pin seating and secure locking tabs.
- If wiring and connectors are good but the pretensioner shows open, replace the driver pretensioner assembly. If pretensioner shows correct resistance but code remains, inspect SRS control unit connector and wiring and consider module fault.
- After repairs, reconnect everything, restore battery, clear SRS codes with a scan tool, and perform SRS system self-check. Confirm the SRS warning lamp behaves normally and codes do not return.
- If codes persist after proper wiring and component replacement, consult manufacturer service manual for module-level diagnostics or perform professional SRS module testing/repair.
Likely causes
- Harness flex point under seat has chafed or broken conductor
- Harness connector pin backed out or corroded (moisture intrusion)
- Pretensioner replaced previously with incorrect part or poor crimp
- Module pin or harness connector damaged during service
- Open squib coil inside pretensioner (component fault)
Fault status
Status
Driver seat belt pretensioner circuit — open circuit detected (OPN). Continuity to pretensioner not detected by SRS control unit.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
Similar codes
Your experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
Your feedback helps improve AI descriptions.
👍 Like
0
👎 Dislike
0
Send to email