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Home / DTC / B2860 — Passenger presence sensor circuit fault

B2860 — Passenger presence sensor circuit fault

Detailed page for trouble code B2860.

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Code

B2860

HUMMER B — Body

Passenger presence sensor circuit fault

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

Causes

  • Damaged or disconnected wiring harness or connector at the passenger presence sensor (under the passenger seat).
  • Failed passenger presence sensor module / seat mat sensor.
  • Short to power or short to ground in sensor circuit.
  • Corrosion, water intrusion, or contamination of the seat mat or connectors.
  • Poor ground or blown fuse supplying the sensor / SDM.
  • Faulty Sensing and Diagnostic Module (SDM) / airbag control module or communication error on CAN bus.

Symptoms

  • Airbag warning lamp illuminated.
  • Passenger airbag OFF indicator incorrectly on or off.
  • No ability to enable/disable passenger airbag according to occupancy.
  • Possible multiple related occupant detection or airbag system DTCs stored.
  • Intermittent warning lamp that changes with seat position or occupant weight.

What to check

  • Retrieve DTCs and freeze-frame data with a capable scanner; record related codes.
  • Perform a visual inspection of the passenger seat area: connectors, harness routing, signs of water or contamination.
  • Inspect and reseat connectors under the passenger seat and check for bent pins or corrosion.
  • Check fuses and power/ground circuits for the SDM/occupant system.
  • Wiggle test wiring while monitoring live data or DTC status to reproduce intermittent faults.
  • Confirm vehicle has correct seat covers and that no aftermarket items are interfering with the mat.

Signal parameters

  • Reference supply to sensor: typically a regulated low-voltage reference from the SDM (commonly ~5 V). Verify against factory values.
  • Signal output from sensor: analog/low-voltage signal that varies with load/occupancy (typically within 0–5 V).
  • Ground integrity: low-resistance connection to chassis ground; measure
  • Continuity check: mat sensor conductors should show continuity when intact; open/infinite indicates broken circuit.
  • CAN / module comms: CAN High/Low idle voltages ~2.5 V; confirm bus activity and message presence using a scan tool or oscilloscope.

Diagnostic algorithm

  1. Connect a scan tool, read and record all DTCs and freeze-frame data. Note whether B2860 is current or historic.
  2. Clear DTCs, perform a system check and see if B2860 returns. If intermittent, move the seat through its range while monitoring diagnostics.
  3. Visually inspect passenger seat, connectors and wiring harness for damage, corrosion, water, or foreign objects. Pay attention to under-seat routing and seat rail pinch points.
  4. With ignition ON, backprobe the sensor connector: verify reference voltage, signal voltage and ground. Compare to factory values; if missing or out of range, trace wiring to the SDM.
  5. Perform continuity and resistance checks on sensor circuit between the seat connector and SDM connector with battery disconnected. Repair any opens, shorts or high-resistance grounds.
  6. If wiring and connectors are good, test or bench-check the occupant sensor mat per factory procedure (resistance or signal vs applied load). Replace mat/module if out of specification.
  7. Inspect SDM/airbag module connectors and fuses. If wiring and sensor verify OK, evaluate SDM for internal faults or communication errors; update software if recommended by TSB/service info.
  8. After repairs, clear codes and perform occupant classification system calibration or learn procedure per service manual. Retest to confirm no recurrence.
  9. If fault persists and all seat-related checks pass, consider professional module bench testing or replacement and consult manufacturer service information.

Likely causes

  • Connector under the passenger seat is loose, pinched, or corroded after a service or seat movement.
  • Seat cushion sensor mat damaged by spillage, cleaning, or physical wear.
  • Wires routed under the seat trapped by seat rails causing intermittent open/short when seat is moved.
  • Failed sensor module (internal short or open) inside the seat assembly.
  • Loss of reference voltage or ground from the SDM/airbag module.

Fault status

⚠️ Status
Passenger presence sensor circuit fault — the occupant detection system has detected an electrical problem with the passenger seat sensor. Airbag system warning is active.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-3.5 hours

Similar codes

B2861 B2862 B2863 B2850 B2770
Repair manuals

Manual library for HUMMER

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Code

B2860

HYUNDAI B — Body

Microphone Fail

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

Causes

  • Damaged or disconnected wiring harness or connector at the passenger presence sensor (under the passenger seat).
  • Failed passenger presence sensor module / seat mat sensor.
  • Short to power or short to ground in sensor circuit.
  • Corrosion, water intrusion, or contamination of the seat mat or connectors.
  • Poor ground or blown fuse supplying the sensor / SDM.
  • Faulty Sensing and Diagnostic Module (SDM) / airbag control module or communication error on CAN bus.

Symptoms

  • Airbag warning lamp illuminated.
  • Passenger airbag OFF indicator incorrectly on or off.
  • No ability to enable/disable passenger airbag according to occupancy.
  • Possible multiple related occupant detection or airbag system DTCs stored.
  • Intermittent warning lamp that changes with seat position or occupant weight.

What to check

  • Retrieve DTCs and freeze-frame data with a capable scanner; record related codes.
  • Perform a visual inspection of the passenger seat area: connectors, harness routing, signs of water or contamination.
  • Inspect and reseat connectors under the passenger seat and check for bent pins or corrosion.
  • Check fuses and power/ground circuits for the SDM/occupant system.
  • Wiggle test wiring while monitoring live data or DTC status to reproduce intermittent faults.
  • Confirm vehicle has correct seat covers and that no aftermarket items are interfering with the mat.

Signal parameters

  • Reference supply to sensor: typically a regulated low-voltage reference from the SDM (commonly ~5 V). Verify against factory values.
  • Signal output from sensor: analog/low-voltage signal that varies with load/occupancy (typically within 0–5 V).
  • Ground integrity: low-resistance connection to chassis ground; measure
  • Continuity check: mat sensor conductors should show continuity when intact; open/infinite indicates broken circuit.
  • CAN / module comms: CAN High/Low idle voltages ~2.5 V; confirm bus activity and message presence using a scan tool or oscilloscope.

Diagnostic algorithm

  1. Connect a scan tool, read and record all DTCs and freeze-frame data. Note whether B2860 is current or historic.
  2. Clear DTCs, perform a system check and see if B2860 returns. If intermittent, move the seat through its range while monitoring diagnostics.
  3. Visually inspect passenger seat, connectors and wiring harness for damage, corrosion, water, or foreign objects. Pay attention to under-seat routing and seat rail pinch points.
  4. With ignition ON, backprobe the sensor connector: verify reference voltage, signal voltage and ground. Compare to factory values; if missing or out of range, trace wiring to the SDM.
  5. Perform continuity and resistance checks on sensor circuit between the seat connector and SDM connector with battery disconnected. Repair any opens, shorts or high-resistance grounds.
  6. If wiring and connectors are good, test or bench-check the occupant sensor mat per factory procedure (resistance or signal vs applied load). Replace mat/module if out of specification.
  7. Inspect SDM/airbag module connectors and fuses. If wiring and sensor verify OK, evaluate SDM for internal faults or communication errors; update software if recommended by TSB/service info.
  8. After repairs, clear codes and perform occupant classification system calibration or learn procedure per service manual. Retest to confirm no recurrence.
  9. If fault persists and all seat-related checks pass, consider professional module bench testing or replacement and consult manufacturer service information.

Likely causes

  • Connector under the passenger seat is loose, pinched, or corroded after a service or seat movement.
  • Seat cushion sensor mat damaged by spillage, cleaning, or physical wear.
  • Wires routed under the seat trapped by seat rails causing intermittent open/short when seat is moved.
  • Failed sensor module (internal short or open) inside the seat assembly.
  • Loss of reference voltage or ground from the SDM/airbag module.

Fault status

⚠️ Status
Passenger presence sensor circuit fault — the occupant detection system has detected an electrical problem with the passenger seat sensor. Airbag system warning is active.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-3.5 hours

Similar codes

B2861 B2862 B2863 B2850 B2770
371

Browse 371 HYUNDAI manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

HYUNDAI

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+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email

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