B3716

Code

Generic B — Body

Occupant Classification Sensor Circuit High

Brand: Generic

Type: B — Body

Views: UK: 7 EN: 14 RU: 10

AI status

Completed

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Page language: EN

Causes

Short to battery / power on OCS signal or supply circuit
Open, corroded or contaminated connector or pin (poor contact)
Damaged occupant classification sensor mat (internal short)
Chafed or damaged wiring harness (pinched, crushed, or water ingress)
Faulty occupant classification module or airbag control module
Incorrect or incomplete system calibration / software fault

Symptoms

SRS / airbag warning lamp illuminated
Passenger airbag enable/disable light incorrect or passenger airbag automatically disabled
Seat occupied detection incorrect (false occupant or no occupant)
Diagnostic trouble codes related to occupant classification stored in SRS module
Possible inability to complete system calibration/relearn

What to check

Retrieve freeze frame and full SRS code list with a capable scan tool and note related codes
Visually inspect seat, sensor mat, connectors, and harness for water damage, corrosion, loose pins, or aftermarket modifications
Check for service bulletins or calibration updates for occupant classification system
With vehicle ignition and safety procedures followed, monitor occupant classification sensor data (raw values/weights) with scan tool while seat is empty and occupied
Perform wiggle test on seat wiring and connectors while watching live data for intermittent behavior
Measure voltage at OCS connector: reference supply (often 5V) and signal line with respect to ground

Signal parameters

Reference voltage typically 5.0 V (manufacturer-specific) — verify with OEM data
Signal high condition: voltage near vehicle battery voltage or above expected signal max (e.g., >4.5 V) often indicates short to power
Signal low/open: voltage near 0 V or infinite resistance indicates short to ground or open circuit
Typical sensor output: varies by design (raw counts, voltage or resistance). Use scan tool live data to compare expected ranges and change with occupant weight
Resistance of intact mat: manufacturer-specific (can be tens to kilo-ohms); short to battery will show very low resistance to +12 V

Diagnostic algorithm

Safety first: disable vehicle battery and follow manufacturer SRS procedures before accessing airbag/occupant sensors.
Connect a capable SRS scan tool, read DTCs and freeze frame, note related codes and timestamps.
Perform visual inspection of the seat, sensor mat, connectors, and harness for water, corrosion, damage, or aftermarket wiring.
With service manual wiring diagrams, identify OCS signal, supply and ground wires. Inspect connector pins for pushed-out, bent, or corroded terminals.
With ignition ON (and following SRS safety), monitor live OCS data. Place known weights or a passenger on the seat and observe expected changes. Note if signal is stuck at a high value.
Measure voltages at the OCS connector: verify reference supply (e.g., 5 V), signal line behavior (should vary with weight), and check for voltage present with seat empty. A steady high near battery voltage suggests short to power.
Check continuity from the OCS sensor pins back to the occupant classification module or airbag ECU; check for shorts to battery (+) and ground. Repair any harness damage.
If wiring and connector are good, disconnect the sensor mat and measure its resistance to check for internal short or open circuits. Compare against OEM specs.
If mat is confirmed faulty, replace occupant classification sensor mat; if mat is good but module reports high, suspect module fault and consider module replacement or reflash per OEM.
After repairs, perform the required occupant classification system calibration/relearn procedure, clear codes, and verify correct operation via scan tool and test weights.
If intermittent or unclear, inspect for water intrusion or seat heater interference and recheck; consult technical service bulletins if available.

Likely causes

Sensor mat fault or internal short raising output voltage
Connector terminal pushed out or bent causing intermittent contact/high resistance that looks like a high signal
Harness short to +12 V from nearby wiring or previous repair
Corrosion/water intrusion in seat area causing leakage current
Faulty OCC module or airbag control module reporting incorrect voltage

Fault status

⚠️ Status

Occupant Classification Sensor Circuit High — sensor circuit voltage above expected range. SRS/airbag warning may be illuminated and passenger airbag logic may be affected.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-2.5 hours

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