Seat Occupant Sensor: Service and Repair
OCCUPANT CLASSIFICATION SENSOR
Removal
WARNING:
- Always wear safety glasses when repairing an air bag supplemental restraint system (SRS) vehicle and when handling an air bag module. This will reduce the risk of injury in the event of an accidental deployment.
- Do not separate components.
- Never probe the connectors on the air bag module. Doing so can result in air bag deployment, which can result in personal injury.
- The safety belt pretensioner is a pyrotechnic device. Always wear safety glasses when repairing an air bag equipped vehicle and when handling a safety belt buckle pretensioner or safety belt retractor pretensioner. Never probe a pretensioner electrical connector. Doing so could result in pretensioner or air bag deployment and could result in personal injury.
- The restraint system diagnostic tool is for restraint system service only. Remove from vehicle prior to road use. Failure to remove could result in injury and possible violation of vehicle safety standards.
- To reduce the risk of personal injury, do not use any memory saver devices.
CAUTION: It is necessary to rezero the OCS system when a front passenger seat cushion is disassembled, a new trim cover installed, or an OCS service kit is installed. A diagnostic tool is used to trigger the active command to carry out rezeroing of the OCS system.
NOTE:
- If a seat equipped with a seat mounted side air bag and/or a safety belt pretensioner (if equipped) system is being serviced, the supplemental restraint system (SRS) must be depowered.
- The air bag warning lamp illuminates when the RCM fuse is removed and the ignition switch is ON. This is normal operation and does not indicate a supplemental restraint system (SRS) fault.
- Occupant classification sensor (OCS) system components (seat cushion foam pad, bladder with pressure sensor and electronic control unit) are calibrated to each other and are serviced as an assembly. The OCS system components are not to be installed separately. If a new OCS system, OCS system component or seat cushion foam pad are needed, a new OCS system service kit (seat cushion foam pad, bladder with pressure sensor and electronic control unit) must be installed as an assembly.
- To identify between a production OCS system and a service OCS system (OCS service kit) inspect the electronic control unit (ECU) electrical connector.A production OCS system allows the disconnect of the ECU electrical connector. A service OCS system (OCS service kit) has the ECU electrical connector glued to the ECU, it cannot and should not be disconnected or altered.
- The SRS must be fully operational and free of faults before releasing the vehicle to the customer.
- Repair is made by installing a new part only. If the new part does not correct the condition, install the original part and carry out the diagnostic procedure again.
All vehicles
1. Remove the passenger seat Service and Repair and depower the system. Service and Repair
2. Remove the front seat backrest.
3. Remove the power seat track or manual seat track.
4. CAUTION: While positioning the seat cushion frame and occupant sensor assembly, be careful not to damage any of the components. Failure to do so can result in component failure.
Release the trim cover J-clips.
Vehicles with an original equipment occupant classification sensor (OCS)
5. Remove the seat cushion pan and OEM occupant classification sensor (OCS) from the foam pad and trim cover.
6. CAUTION: Use care when separating the seat upholstery from the hook-and-loop strip, or the hook-and-loop strip can be torn from the seat cushion foam pad.
If installing a new OCS or trim cover, release the hook-and-loop strips and remove the seat cushion trim cover from the foam pad.
7. Remove the pin-type retainers.
8. Separate the pressure sensor from the bracket.
1 Bend and release the retaining tab (not shown) holding the pressure sensor in place.
2 Slide the pressure sensor off the bracket.
3 Disconnect the electrical connector.
9. NOTE: Make note of the opening that the pressure sensor and hose are being fed through on the seat cushion support assembly for installation purposes.
Separate the OCS bladder and pressure sensor from the seat cushion frame.
- Feed the pressure sensor and hose through the seat cushion support assembly.
10. Remove the electronic control unit (ECU) from the seat cushion frame bracket.
1 Disconnect the ECU electrical connector.
2 Remove the rivets.
3 Remove the ECU.
Vehicles with a service kit occupant classification sensor (OCS)
11. CAUTION: Use care when separating the seat upholstery from the hook-and-loop strip, or the hook-and-loop strip can be torn from the seat cushion foam pad.
If installing a new OCS or trim cover, release the hook-and-loop strips and remove the seat cushion trim cover from the foam pad.
12. Separate the occupant classification sensor (OCS) components from the seat cushion frame.
1 Cut the tie straps.
2 Remove the rivets and separate the electronic control unit (ECU) from the seat cushion frame bracket.
3 Bend and release the retaining tabs holding the pressure sensor in place.
4 Slide the pressure sensor off the bracket
5 Disconnect the electrical connector.
13. Remove the OCS from the seat cushion frame.
- Feed the hose, pressure sensor, wire harness, electrical connector and electronic control unit through the seat cushion frame support assembly.
Installation
All vehicles
1. Bend the retaining ear back on the occupant sensor component bracket.
Vehicles having a service kit occupant classification sensor installed
2. WARNING: Do not separate components.
CAUTION:
- Inspect the occupant classification sensor assembly, seat cushion frame and support assembly for any foreign objects, before installing the occupant classification sensor assembly to the seat cushion frame. If any foreign objects are found, remove them. Failure to do so may result in personal injury, in the event of an air bag deployment.
- Failure to route the seat occupant sensor components through the correct seat cushion support opening can cause component failure.
- While positioning the seat cushion frame and occupant classification sensor assembly, be careful not to damage any of the components. Failure to do so can result in component failure.
NOTE: If the original equipment occupant classification sensor (OCS) is not being installed, install a service kit OCS using all parts in the kit.
Position the occupant classification sensor assembly to the seat cushion frame.
- Using a service occupant classification sensor, feed the electronic control unit, electrical connector, wire harness, pressure sensor, and hose through the largest opening at the front of the seat cushion frame support assembly.
- Position the seat cushion pad and bladder to the seat cushion frame.
3. NOTE: When installing a service part occupant classification sensor, the main seat wire harness pressure sensor electrical connector does not get used.
Attach and connect the occupant classification sensor components.
1 Position the electronic control unit onto the seat cushion frame bracket and install new rivets.
2 Install the pressure sensor onto the seat cushion frame bracket, making sure the retaining ear is completely engaged.
- When installed correctly, an audible click will be heard and the pressure sensor will not be able to be removed from its bracket without disengaging the retaining ear.
3 Connect the main seat wire harness occupant classification sensor electrical connector to the service part occupant classification sensor electrical connector.
4 Tie strap all loose wire harnesses and electrical connectors safely out of the way.
4. CAUTION:
- It is necessary to rezero the OCS system when a front passenger seat cushion is disassembled, a new trim cover installed, or an OCS service kit is installed. A diagnostic tool is used to trigger the active command to carry out rezeroing of the OCS system.
- Inspect the seat cushion pad and seat cushion trim cover for any foreign objects, before installing the seat cushion trim cover to the seat cushion pad. If any foreign objects are found, remove them. Failure to do so may result in personal injury, in the event of an air bag deployment.
Align the seat cushion trim cover to the seat cushion foam pad and attach the hook-and-loop strips.
Vehicles having an original equipment occupant classification sensor installed
5. CAUTION: While positioning the seat cushion frame and occupant classification sensor assembly, be careful not to damage any of the components. Failure to do so can result in component failure.
NOTE: The ECU must be correctly positioned and securely fastened in place. Failure to do so can set a diagnostic trouble code (DTC) in the restraints control module (RCM).
Install the electronic control unit (ECU).
1 Position the ECU to the bracket.
2 Install the rivets.
3 Connect the electrical connector.
6. CAUTION:
- Inspect the occupant classification sensor assembly, seat cushion frame and support assembly for any foreign objects before installing the occupant classification sensor assembly to the seat cushion frame. If any foreign objects are found, remove them. Failure to do so may result in personal injury, in the event of an air bag deployment.
- Failure to route the seat occupant sensor components through the correct seat cushion support opening can cause component failure.
- While positioning the seat cushion frame and occupant sensor assembly, be careful not to damage any of the components. Failure to do so can result in component failure.
Position the occupant classification sensor (OCS) assembly to the seat cushion frame.
- Feed the pressure sensor with hose through the largest opening at the front of the seat cushion frame support assembly.
7. CAUTION: Inspect the occupant classification sensor bladder, seat cushion frame and support assembly for any foreign objects, before installing the occupant classification sensor to the seat cushion frame. If any foreign objects are found, remove them. Failure to do so may result in personal injury, in the event of an air bag deployment.
Install the pin-type retainers holding the OCS bladder to the seat cushion frame.
8. Install the pressure sensor.
1 Install the pressure sensor onto the seat cushion frame bracket, making sure the retaining ear is completely engaged.
- When installed correctly, an audible click will be heard and the pressure sensor will not be able to be removed from its bracket without disengaging the retaining ear.
2 Connect the electrical connector.
9. CAUTION:
- It is necessary to rezero the OCS system when a front passenger seat cushion is disassembled, a new trim cover installed, or an OCS service kit is installed. A diagnostic tool is used to trigger the active command to carry out rezeroing of the OCS system.
- Inspect the seat cushion pad and seat cushion trim cover for any foreign objects, before installing the seat cushion trim cover to the seat cushion pad. If any foreign objects are found, remove them. Failure to do so may result in personal injury, in the event of an air bag deployment.
Align the seat cushion trim cover to the seat cushion foam pad and attach the hook-and-loop strips.
10. CAUTION: Inspect the seat cushion pad and frame for any foreign objects before installing the seat cushion pad to the seat cushion frame. If any foreign objects are found, remove them. Failure to do so may result in personal injury, in the event of an air bag deployment.
Position the seat cushion pan and OEM occupant classification sensor (OCS) into the foam pad and trim cover.
All vehicles
11. Attach the trim cover J-clips.
12. Install the power seat track or manual seat track.
13. Install the front seat backrest.
14. Install the passenger seat Service and Repair and repower the system. Service and Repair Do not prove out the system at this time.
15. WARNING: Do not separate components.
CAUTION:
- It is necessary to rezero the OCS system when a front passenger seat cushion is disassembled, a new trim cover installed, or an OCS service kit is installed. A diagnostic tool is used to trigger the active command to carry out rezeroing of the OCS system.
- Make sure the seat is completely assembled before rezeroing.
- The following precautions must be taken before rezeroing the OCS system:
- Make sure the OCS system components are connected and no faults are present.
- Make sure the OCS system is not at a temperature below 0°C (32°F) or above 45°C (113°F) when initiating the rezeroing process. If the vehicle has been exposed to extreme cold or hot temperatures, the vehicle must be exposed and kept at a temperature within the limits, 0°C to 45°C (32°F to 113°F) for a minimum of 30 minutes.
- Make sure nothing is present on the passenger seat before rezeroing and nothing is placed on the seat during the rezeroing process.
- Make sure a minimum eight second time period has passed after cycling the ignition switch ON before the rezeroing process.
NOTE:
- For best results in rezeroing, the OCS system should be at or near room temperature, 10°C to 29°C (50°F to 85°F).
- When using a New Generation STAR (NGS) Tester you must use the appropriate memory card with the latest update to carry out this function. To rezero the OCS system:
- select "SERVICE BAY FUNCTIONS"
- select "RCM "
- select "SYSTEM RESET"
- select the vehicle from the menu
- view the on-screen information, then press "TRIGGER"
The NGS screen will then display "OCS RESET: REZERO." Press "DONE" (button 8) to rezero the OCS system. The NGS will return to the vehicle menu once rezeroing of the OCS system is complete.
NOTE:
- To rezero the OCS system using the Worldwide Diagnostic System (WDS):
- select the "Toolbox" icon
- select "Body" from the menu
- select "Restraints" from the menu
- select "Seat Weight Sensor ReZero"
After selecting "Seat Weight Sensor ReZero", follow the on-screen prompts to carry out rezeroing of the OCS system.
- If the first attempt to rezero the OCS system is unsuccessful, a second attempt must be made.
Rezero the occupant classification sensor.
- With the front passenger seat empty, use a diagnostic tool to trigger the active command and rezero the occupant classification sensor.
16. NOTE: The ignition switch must be cycled after rezeroing the OCS system.
Cycle the ignition switch from ON to OFF.
17. Prove out the supplemental restraint system (SRS) as follows:
Turn the ignition key from ON to OFF. Wait 10 seconds, then turn the key back to ON and visually monitor the air bag indicator with the air bag modules installed. The air bag indicator will light continuously for approximately six seconds and then turn off. If an air bag supplemental restraint system (SRS) fault is present, the air bag indicator will either:
- fail to light.
- remain lit continuously.
- flash.
The flashing might not occur until approximately 30 seconds after the ignition switch has been turned from the OFF to the ON position. This is the time required for the restraints control module (RCM) to complete the testing of the SRS. If the air bag indicator is inoperative and a SRS fault exists, a chime will sound in a pattern of five sets of five beeps. If this occurs, the air bag indicator and any SRS fault discovered must be diagnosed and repaired.
Clear all continuous DTCs from the restraints control module using a diagnostic tool.
18. Check the active restraint system for correct operation.