Code
B0064
HUMMER
B — Body
Occupant Classification System (OCS) Fault
Views:
UK: 19
EN: 28
RU: 20
AI status
Completed
Completed
100%
Causes
- Damaged or contaminated occupant classification sensor mat (seat cushion sensor)
- Broken, chafed or pinched wiring harness under the passenger seat
- Corroded or loose connector(s) at the seat or OCS module
- Faulty OCS control module or restraint control module (RCM/SDM)
- Loss of power or ground to the OCS circuit
- Improper seat removal/installation, aftermarket seat/heater installation, or foreign objects trapped under the seat cushion
Symptoms
- SRS/Airbag warning lamp illuminated
- Passenger airbag status unknown or passenger airbag disabled
- Inability to correctly detect or classify occupant (passenger airbag may not deploy or may be forced off)
- Possible audible chime or dashboard message related to passenger detection
- DTC B0064 present in the airbag/RCM/SDM memory
What to check
- Retrieve codes and freeze frame data with a compatible scan tool (RCM/SDM/OBC module access).
- Check for other related SRS DTCs that can indicate wiring or module issues.
- Visually inspect the passenger seat cushion and underside for damage, moisture, or foreign objects.
- Inspect connectors and wiring under the passenger seat for corrosion, pin damage, loose terminals or chafing.
- Verify vehicle battery voltage and ground integrity; low system voltage can cause faults.
- Check for proper communication on the airbag/CAN network using a scan tool.
Signal parameters
- OCS status/classification message on RCM/CAN (e.g., Occupied/Unoccupied/Child/Unknown)
- Sensor mat supply voltage: nominal battery voltage (approx. 12 V) when powered
- Sensor mat ground continuity and circuit resistance (resistance should change with applied load)
- Circuit continuity between sensor mat and OCS/RCM connector pins
- Presence/absence of CAN messages from OCS to RCM
- Diagnostic trouble code history and frequency/count (current, intermittent or stored)
Diagnostic algorithm
- Connect a factory-level or capable scan tool. Read and record all SRS/airbag codes and freeze frame data. Note related codes and history.
- Verify battery state of charge and charging system. Low voltage can produce false SRS faults—restore normal battery voltage and retest.
- Clear the codes and perform an ignition cycle. If B0064 returns immediately, proceed to physical inspection.
- Visually inspect the passenger seat cushion and underside for water intrusion, stains, damage or foreign objects that could affect the mat.
- With ignition off, disconnect the passenger seat connectors and inspect pins for corrosion, bent pins, moisture, or pushed-out locks. Reconnect securely and retest.
- Perform a wiggle test of the seat wiring harness while monitoring live OCS/RCM data with the scan tool to see if status changes or the code triggers.
- Measure continuity and resistance of the sensor mat circuit per manufacturer procedure/specs (check for opens/shorts to ground). Compare to expected behavior (resistance should vary when weight is applied).
- Verify power and ground at the OCS/seat module connector with ignition on. Repair any open or high resistance connections.
- Check CAN communication between OCS and RCM (no communication or message errors indicate module or wiring fault).
- If wiring, connectors and power/ground are good but fault persists, follow OEM guidance: either replace the occupant sensor mat or the OCS module as directed, then perform required calibration/relearn procedure for the occupant classification system.
- After repairs, clear codes and perform full system verification including calibration, road test, and recheck for DTC reappearance.
Likely causes
- Seat cushion sensor mat damage or moisture contamination
- Connector corrosion or poor pin contact at under‑seat plug
- Wiring short to ground or open in the sensor mat circuit
- OCS module internal fault or loss of CAN communication
- Failed occupant sensor due to airbag deployment or prior repairs
Fault status
Status
Occupant Classification System (OCS) fault detected. The OCS sensor mat, wiring, connector, or module may be faulty or improperly calibrated. The fault typically causes the airbag/SRS warning lamp to illuminate and can disable or alter passenger airbag deployment.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
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