Seat Occupant Sensor: Service and Repair
OCCUPANT CLASSIFICATION SENSORWorldwide Diagnostic System (WDS):
Special Tool(s)
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 occupant classification sensor (OCS) system when a front passenger seat cushion is disassembled, a new trim cover installed, or an OCS service kit is installed. A scan tool is used to trigger the active command to carry out rezeroing of the OCS system.
NOTE:
- If a seat equipped with a supplemental restraint system (SRS) component 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.
- OCS system components (seat cushion pan, 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 pan, seat cushion foam pad are needed, a new OCS system service kit (wiring harness, seat cushion pan, 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.
- A production OCS system is shown, an OCS service kit is similar.
All seats
1. Depower the system.
2. Remove the passenger seat.
3. CAUTION: Note the position and routing of the wiring harness(es) to aid installation. An incorrectly routed wiring harness may lead to the wires becoming damaged on the seat mechanism.
Detach the safety belt buckle switch wiring harness from the underside of the cushion.
Heated seats
4. From the back of the large connector at the outboard side of the seat, release the tab at the top and remove the heated seat electrical connector insert from the large connector.
5. Disconnect the cushion-to-backrest feed heated seat electrical connector.
All seats
6. Disconnect the belt tension sensor and separate the connector from the cushion pan.
7. From the back of the large connector at the outboard side of the seat, release the tab at the top and remove the occupant classification sensor electrical connector inserts from the large connector.
8. Remove the bolts and the front seat cushion.
9. CAUTION: While positioning the seat cushion pan and occupant classification sensor (OCS) assembly, be careful not to damage any of the components. Failure to do so can result in component failure.
Detach the front edge of the seat cover.
- Detach the retaining strip.
10. Remove the hog rings.
11. CAUTION: If installing only the front passenger seat cushion trim cover, the occupant classification sensor must be rezeroed.
Separate the trim cover from the cushion foam pad.
1 Roll the trim cover back to access the hog rings.
2 Remove the hog rings and the cushion trim cover.
Heated seats
12. CAUTION: Remove the paper strips covering the adhesive before adhering the heater mat to the foam pad, otherwise damage to the seat may occur.
NOTE: A new heated seat mat can be attached to a foam pad where an old heated seat mat was removed. A used heated seat mat should not be reattached to any foam pad.
Separate the cushion heated seat element from the foam pad.
All seats
13. Remove the occupant classification sensor (OCS) as an assembly (wiring harness, seat cushion pan, seat cushion foam pad, bladder with pressure sensor and electronic control unit).
Installation
All seats
1. Make sure the belt tension sensor wire harness is routed between the OCS electronic control unit and the mounting bracket.
Heated seats
2. CAUTION: Remove the paper strip covering the adhesive before adhering the heater mat to the foam pad. Otherwise damage to the seat can occur.
Remove the paper strips at the rear of the cushion heated seat element.
3. Center and align the cushion heated seat element to the rear edge of the cushion foam pad. Adhere the rear of the cushion heated seat element to the cushion foam pad.
- Make sure the heater element ear openings align to the cushion foam pad front wire windows at each side for trim cover installation.
4. Tuck the cushion heated seat element into the cushion foam pad rear trench.
5. CAUTION: Remove the paper strip covering the adhesive before adhering the heater mat to the foam pad. Otherwise damage to the seat can occur.
Remove the paper strip at the front of the cushion heated seat element.
6. Adhere the front of the cushion heated seat element to the cushion foam pad. Tuck the 2 cushion heated seat element side ears into the cushion foam pad side trenches.
All seats
7. CAUTION: Inspect the components for any foreign objects before installing the seat cushion trim cover. 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.
Attach the cushion trim cover to the cushion foam pad.
1 Position the cushion trim cover to the cushion foam pad
2 Install the hog rings.
- If the seat is equipped with heat, make sure the hog rings attaching the wires from the cushion foam pad and cushion trim cover are attached through the cushion heated seat element windows.
8. Attach the trim cover to the seat cushion pan with hog rings.
9. Attach the front edge J-clip of the cushion trim cover to the cushion pan.
10. Install the bolts and the front seat cushion.
11. Connect the occupant classification sensor electrical connector inserts back into the large connector.
12. Connect the belt tension sensor and attach the connector to the cushion pan.
Heated seats
13. Install the heated seat electrical connector insert into the large connector.
14. Connect the cushion to backrest feed heated seat electrical connector.
All seats
15. Attach the safety belt buckle switch wiring harness from the underside of the cushion.
16. Install the passenger seat.
17. Repower the system. Do not prove out the SRS at this time.
18. 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 scan 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 an NGS+ (NGS with Vehicle Communication Module (VCM) and the latest software update) to rezero the OCS system:
- select "FUNCTION TEST"
- select "SYSTEM RESET"
- 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 display "TEST/FUNCTION SUCCESSFUL" 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.
NOTE: 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 scan tool to trigger the active command and rezero the occupant classification sensor.
19. NOTE: The ignition switch must be cycled after rezeroing the OCS system.
Cycle the ignition switch from ON to OFF.
20. 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 at a 5 Hz rate (RCM not configured).
The air bag indicator may not illuminate 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 scan tool.