B2615

Code

Generic B — Body

Occupant Classification Sensor Circuit Fault

Brand: Generic

Type: B — Body

Views: UK: 14 EN: 20 RU: 21

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Open or shorted wiring in occupant classification sensor harness
Corroded or loose connector pins at sensor or airbag control module
Water intrusion or contamination of the seat sensor pad
Damaged or failed occupant classification sensor (mat/load cell module)
Faulty ground or reference voltage to the sensor
Intermittent connection due to seat movement or damaged seat frame

Symptoms

SRS / airbag warning lamp illuminated
Passenger airbag status incorrect or disabled when occupied
Seat belt reminder or chime behavior inconsistent
Inability to register occupant weight/occupancy in live data
DTC persists after battery reset or seat movement

What to check

Read and record all SRS/occupant-related DTCs with a capable scan tool
Visual inspection of seat bottom area for water, debris, or damage
Inspect connectors and pins at the sensor and airbag control module for corrosion or bent pins
Wiggle test harness and connector while monitoring live data to check for intermittent faults
Confirm correct reference voltage and ground at the sensor connector with ignition ON (per manufacturer procedure)
Compare live sensor values (voltage or weight reading) to expected behavior when seat is unloaded and when a known weight is applied

Signal parameters

Sensor power/reference: typically a stable 5 V (verify exact value for vehicle)
Signal output: analog voltage (0–5 V) or module-reported weight/occupancy value — should change smoothly with load
Expected behavior: steady, noise-free signal at rest; progressive change when weight is applied/removed
Open-circuit: signal may read 0 V or high-impedance; short-to-voltage: fixed near reference voltage
CAN/serial: some systems report occupancy over CAN — messages should appear at normal update rate (check for missing frames)

Diagnostic algorithm

Safety first: follow manufacturer SRS procedures — disable vehicle battery and wait the specified time before disconnecting SRS connectors.
Scan for DTCs and view live data/parameter for occupant classification sensor. Note sensor readings at rest.
Clear the code and attempt to reproduce. If code returns, continue with diagnostics.
Perform a visual inspection of seat cushion area, sensor mat, and wiring for damage, water, or foreign objects.
With ignition ON (per safety rules), probe the sensor connector: verify reference voltage, ground continuity, and signal voltage. Compare to expected values from service manual.
Wiggle and move the seat and harness while watching live data to find intermittent opens/shorts. Pay attention to seat rails and connector stress points.
Measure continuity between sensor connector and airbag control module pins for each conductor to find opens or high resistance.
If the signal is present but implausible, apply a known weight or use a calibrated resistive fixture (per service manual) to verify sensor response.
Inspect and reseat connectors; clean corrosion with appropriate contact cleaner if minor. Replace connector or harness if pins are damaged.
If wiring and connectors test good, replace the occupant classification sensor mat/module per manufacturer procedure and re-test.
If replacement sensor does not clear the fault, suspect airbag/occupant classification control module fault or programming issue — consult manufacturer for reprogramming or module replacement.
After repair, clear DTCs and verify system operation in live data, confirm SRS lamp behavior and passenger airbag status under different occupancy conditions.