B3184

Code

Generic B — Body

Passenger Presence Sensor Circuit Malfunction

Brand: Generic

Type: B — Body

Views: UK: 8 EN: 8 RU: 9

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Page language: EN

Causes

Damaged or shorted wiring harness under the passenger seat
Corroded or disconnected connector at the sensor or module
Failed passenger presence sensor (seat mat, pressure sensor, or capacitance sensor)
Water/moisture ingress into the seat assembly or sensor
Aftermarket seat covers, cushions or repairs altering sensor readings
Faulty occupant classification (airbag) control module or software calibration

Symptoms

Passenger airbag status light may illuminate or show a fault
Passenger presence indicator may show incorrect occupant detection (on/off)
Airbag disablement for passenger seat (passenger airbag OFF) when occupied
Diagnostic trouble code stored and possibly other related SRS/occupant system codes
Intermittent or persistent DTC depending on wiring condition

What to check

Scan vehicle with a suitable diagnostic tool; read freeze frame and related SRS/occupant codes
Visually inspect seat underside for loose connectors, damaged harness, or water ingress
Verify connectors are fully seated and locking tabs are intact
Check for aftermarket seat covers, cushions, or foreign objects on the seat
Confirm proper power and ground to the occupant classification module and sensor
Observe passenger presence status live data while applying/removing weight to the seat

Signal parameters

Sensor supply: typically switched 5 V or vehicle reference voltage from control module
Signal output: typically a DC voltage or resistance/capacitance reading that changes with occupant load (varies by manufacturer)
Expected behavior: signal should change smoothly when weight is applied/removed; not jump to open/short values
Open circuit: infinite or very high resistance / signal absent
Short to ground or battery: signal near 0 V or near supply voltage respectively
CAN/serial: some systems send passenger presence as a status byte on the airbag network — must be correct and consistent

Diagnostic algorithm

Use scan tool to confirm B3184 and note any related codes (SRS/occupant classification). Record freeze frame and live data for passenger presence.
Visually inspect passenger seat: check for wetness, foreign objects, seat covers, and visible damage to the mat/harness/connectors.
With ignition ON (follow manufacturer's safety procedures for SRS work), monitor the passenger presence sensor live data while a known weight is placed on the seat. Note normal vs abnormal response.
Check connector continuity and pins for corrosion or bent pins. Disconnect harness and inspect both sides; apply contact cleaner if needed.
Measure supply voltage and ground at the sensor connector. Compare to expected reference (typically vehicle reference voltage or battery as per service data).
Measure signal output (voltage or resistance) at the sensor connector while changing seat load; look for expected variation and no intermittent dropouts.
Perform a wiggle test on the wiring harness with live-data monitoring to locate intermittent open/short conditions.
If wiring and connectors are good, compare sensor resistance/capacitance values to the service manual. Replace sensor mat/module if out of spec or physically damaged.
If sensor and wiring check good, check occupant classification/control module mounting, grounds, and CAN communication. Replace or reprogram module only after verifying upstream components.
After repairs, clear codes and confirm fault does not return under normal use. Follow manufacturer procedures for re-initialization/calibration of occupant classification systems if required.
Safety note: Occupant presence circuits are part of the supplemental restraint system (SRS). Follow manufacturer SRS precautions and procedures when working on or near the seat and airbag system.

Likely causes

Open or short in the passenger presence sensor signal or supply circuit
Intermittent connector contact from seat movement
Sensor mat resistance or capacitance out of specification due to damage
Contamination or moisture causing incorrect sensor output
Module reporting or CAN communication error with the Occupant Classification System