B3484

Code

Generic B — Body

Passenger Presence Sensor Circuit Malfunction

Brand: Generic

Type: B — Body

Views: UK: 5 EN: 11 RU: 8

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Page language: EN

Causes

Open or shorted wiring between passenger presence sensor and SRS/BCM
Corroded, loose, or damaged connector under the passenger seat
Faulty passenger presence sensor mat/module inside the seat
Water/moisture ingress or contamination of the seat sensor
Aftermarket seat covers, padding, or seat repair that disturbed the sensor
Faulty SRS/BCM/occupant classification control module or software fault

Symptoms

SRS/airbag warning light illuminated
Passenger airbag disabled indicator or passenger airbag status incorrect
Seat belt reminder or seat-occupancy related functions behaving incorrectly
Stored B3484 DTC and possibly additional related codes
Intermittent occupant detection (airbag enabling/disabling unpredictably)

What to check

Read all stored SRS/BCM codes and freeze frame data with a capable scan tool
Visually inspect passenger seat, connectors, wiring harness and under-seat area for damage, corrosion, or foreign objects
Confirm no aftermarket seat covers, heaters or repairs that could affect the sensor
With key ON (engine off) measure sensor supply voltage and ground at the harness connector
Perform continuity and resistance checks on wiring between sensor and control module
Wiggle harness and seat while monitoring live data or DTCs to locate intermittent faults

Signal parameters

Supply voltage: typically a regulated reference (commonly ~5 V) — verify per vehicle manual
Signal output: typically a variable 0–5 V signal or variable resistance/capacitance depending on design
Unoccupied vs occupied: unoccupied and occupied values differ by manufacturer — example ranges (manufacturer specific): unoccupied ~low voltage/ high resistance; occupied ~mid-to-high voltage/ lower resistance
Fault conditions: open = no signal/OL, short-to-ground ≈ 0 V, short-to-power ≈ supply voltage, intermittent = fluctuating signal
Note: exact numeric values are manufacturer-specific; confirm expected values in the service manual before replacing components

Diagnostic algorithm

Record codes and freeze-frame with scan tool. Do not clear codes until initial checks are done. Note any additional SRS or communication codes.
Follow manufacturer SRS safety procedure before working near airbags (disable battery or follow control module isolation and required wait times).
Visually inspect passenger seat area: seat cover, foam, sensor mat, and connectors for contamination, water damage, or physical damage.
Access the passenger presence sensor connector (under the seat). Check for bent pins, corrosion, pushed-back terminals, and secure mating.
With key ON (engine off) and using appropriate safety precautions, measure reference supply voltage, sensor signal, and ground at the connector. Compare to factory specs.
Perform continuity and resistance checks from the sensor connector to the occupant classification/control module connector. Repair any open/short/low-resistance faults.
Wiggle test wiring and seat position while monitoring live sensor values or DTC status to detect intermittent faults; repair harness/routing as required.
If wiring and connector are good but signal values are out of spec, replace the passenger presence sensor mat/module or the seat assembly per service procedure.
If sensor and wiring OK, consider module fault: check communication to BCM/SRS module and related modules; test/replace control module only after other causes excluded.
After repair, clear DTCs and perform any required occupant classification system relearn/calibration per manufacturer. Verify proper operation and that codes do not return.

Likely causes

Damaged connector or wiring under the passenger seat (highly likely)
Sensor mat/module failure due to age, impact, or water (likely)
Intermittent connection caused by seat movement or broken pins (likely)
Control module internal fault or configuration/calibration issue (possible)

Fault status

⚠️ Status

Passenger Presence Sensor Circuit Malfunction (B3484). The occupant detection circuit for the front passenger seat is reporting an abnormal electrical condition (open, short, out-of-range or intermittent signal). This may disable the passenger airbag and trigger the SRS warning lamp. Inspect wiring, connector, sensor mat, and perform necessary repairs and any required relearn procedures.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0 - 2.5 hours