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Home / DTC / B1B77 — Side impact sensor(RH) 3

B1B77 — Side impact sensor(RH) 3

Detailed page for trouble code B1B77.

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Code

B1B77

MITSUBISHI B — Body

Side impact sensor(RH) 3

Brand: MITSUBISHI
Type: B — Body
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Failed or degraded RH side impact sensor
  • Damaged, pinched or chafed wiring harness to the sensor
  • Loose, corroded or contaminated connector at the sensor or SRSCM
  • Water intrusion or moisture in connector or sensor
  • Sensor mounting loosened or physically damaged by impact or service
  • Poor ground or supply voltage to the sensor circuit

Symptoms

  • SRS/Airbag warning lamp illuminated on instrument panel
  • One or more side airbags or seatbelt pretensioners may be disabled
  • Vehicle may fail safety inspection or self-test
  • Possible stored freeze-frame or related SRS codes
  • No obvious drivability symptoms (electrical fault only) until SRS event

What to check

  • Read codes and freeze-frame data with a capable scan tool that supports Mitsubishi SRS functions
  • Attempt to clear the code and see if it returns (helps detect intermittent faults)
  • Visually inspect the RH side impact sensor, its mounting, and surrounding area for damage
  • Inspect the sensor connector for corrosion, bent pins, moisture, or contamination
  • Follow the harness from the sensor to the SRSCM looking for chafing, breaks, or previous repair splice points
  • Backprobe the sensor connector and measure signal/reference/ground with a multimeter or oscilloscope while monitoring data with a scan tool

Signal parameters

  • Supply voltage to sensor (battery/ignition feed) — verify present and stable
  • Reference voltage provided by SRSCM (Vref) to the sensor — compare to factory spec
  • Sensor signal voltage or output waveform at rest and when tapped (monitor with scope if possible)
  • Signal circuit continuity between sensor and SRSCM (check for opens/shorts to ground or battery)
  • Resistance/impedance of sensor circuit where applicable (compare to service data)
  • Presence and integrity of CAN/LIN messages if sensor communicates digitally (verify with scan tool)

Diagnostic algorithm

  1. Connect manufacturer-capable scan tool; record all SRS codes and freeze-frame data. Note whether code is current or historical.
  2. Clear codes and perform a key cycles test to see if B1B77 returns (helps identify intermittent faults).
  3. Visually inspect RH side impact sensor area, mounting, and harness for damage, water intrusion or loose connectors.
  4. Disconnect battery per safety procedures for SRS work if required by service manual before disconnecting airbag connectors. Follow vehicle-specific safety steps.
  5. With battery reconnected and scanner attached (or per manual), backprobe the sensor connector: verify supply, reference, ground and signal lines while comparing to spec. Use oscilloscope for transient/AC signals if available.
  6. Perform continuity check from sensor pins to SRSCM connector to detect opens or shorts to chassis/battery.
  7. Perform wiggle test on harness and connector while monitoring signal or scan tool for code reappearance.
  8. If wiring and connectors test good and sensor output out of spec, replace the RH side impact sensor; use OEM part and torque/mount per manual.
  9. After repair, clear codes and cycle ignition; perform required SRS self-tests and any calibration/initialization procedures specified by manufacturer.
  10. Confirm no SRS lamp, no recurrence of code, and verify proper system readiness before returning vehicle to service.

Likely causes

  • Corroded/loose connector at the side impact sensor
  • Damaged wiring harness between sensor and SRSCM (chafe, cut, short)
  • Failed side impact sensor
  • Moisture/water ingress at connector
  • Less likely: SRSCM internal fault

Fault status

⚠️ Status
Side impact sensor (RH) #3 circuit/signal fault detected by SRS control module — signal out of expected range or no response. SRS warning lamp illuminated; related side airbag/pretensioner may be disabled until resolved.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

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406

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