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Seat Occupant Classification Module - Air Bag

Restraints and Safety Systems › Relays and Modules - Restraints and Safety Systems
Unified entry — merged from multiple cross-listed pages in the original manual.
Procedures
Occupant Classification Module - Installation5 steps
⚠ WARNING
To avoid serious or fatal injury on vehicles equipped with airbags, disable the Supplemental Restraint System (SRS) before attempting any steering wheel, steering column, airbag, Occupant Classification System (OCS), seat belt tensioner, impact sensor or instrument panel component diagnosis or service. Disconnect and isolate the battery negative (ground) cable, then wait two minutes for the system capacitor to discharge before performing further diagnosis or service. This is the only sure way to disable the SRS. Failure to follow these instructions may result in accidental airbag deployment.
ℹ NOTE
A non-calibrated Occupant Classification Module (OCM) is available for separate service replacement. The OCM and all of the other components of the Occupant Classification System (OCS) including the passenger side front seat, the seat weight sensors, and the passenger seat adjusters, cushion, back, frame, foam, springs, and wiring harness are a factory-calibrated and assembled unit. Any time any one of these components is removed or replaced for any reason, the OCM must be re-calibrated using a diagnostic scan tool, the Occupant Classification Seat Weight special tool, and the Occupant Classification System Verification Test. Refer to the appropriate diagnostic procedures.
Fig. 1
Fig. 1
  1. Reach under the front edge of the passenger side front seat cushion to carefully position the Occupant Classification Module (OCM) (1) to the top of the mounting bracket (4) on the inboard passenger side front seat riser (2). When the OCM is correctly positioned, the connector receptacles on the module will be pointed forward.
  2. Install and tighten the two screws (3) that secure the OCM to the mounting bracket. Tighten the screws to 2 Nm (20 in. lbs.).
  3. Reconnect the two seat wire harness connectors to the OCM connector receptacles located on the forward-facing end of the module. Be certain that the latches on each connector are fully engaged.
  4. Do not reconnect the battery negative cable at this time. The Supplemental Restraint System (SRS) Verification Test procedure should be performed following service of any SRS component. Service and Repair.
  5. Following successful completion of the SRS Verification Test procedure, perform the Occupant Classification System Verification Test using a diagnostic scan tool. Refer to the appropriate diagnostic procedures.
Occupant Classification Module - Removal4 steps
⚠ WARNING
To avoid serious or fatal injury on vehicles equipped with airbags, disable the Supplemental Restraint System (SRS) before attempting any steering wheel, steering column, airbag, Occupant Classification System (OCS), seat belt tensioner, impact sensor or instrument panel component diagnosis or service. Disconnect and isolate the battery negative (ground) cable, then wait two minutes for the system capacitor to discharge before performing further diagnosis or service. This is the only sure way to disable the SRS. Failure to follow these instructions may result in accidental airbag deployment.
ℹ NOTE
A non-calibrated Occupant Classification Module (OCM) is available for separate service replacement. The OCM and all of the other components of the Occupant Classification System (OCS) including the passenger side front seat, the seat weight sensors, and the passenger seat adjusters, cushion, back, frame, foam, springs, and wiring harness are a factory-calibrated and assembled unit. Any time any one of these components is removed or replaced for any reason, the OCM must be re-calibrated using a diagnostic scan tool, the Occupant Classification Seat Weight special tool, and the Occupant Classification System Verification Test. Refer to the appropriate diagnostic procedures.
Fig. 1
Fig. 1
  1. Disconnect and isolate the battery negative cable. Wait two minutes for the system capacitor to discharge before further service.
  2. Reach under the front edge of the passenger side front seat cushion to access and disconnect the two seat wire harness connectors from the Occupant Classification Module (OCM) (1) connector receptacles located on the forward-facing end of the module.
  3. Remove the two screws (3) that secure the OCM to the top of the mounting bracket (4) on the inboard passenger side front seat riser (2).
  4. Remove the OCM from under the passenger side front seat cushion.
Occupant Classification Module - Descriptionreference
Fig. 1
Fig. 1
DESCRIPTION The Occupant Classification Module (OCM) (1) is secured with two screws to a stamped metal bracket on the inboard passenger side front seat riser beneath the seat cushion. Concealed within a hollow in the center of the molded plastic OCM housing is a microprocessor and the other electronic circuitry of the module. The module housing is sealed to enclose and protect the internal electronic circuitry. Four mounting tabs (2) and two connector receptacles (3) are integral to the OCM housing. The two mounting tabs designed to accept self tapping screws are used to secure the module to the mounting bracket, while the remaining two mounting tabs are unused in this application. The connector receptacles contain terminal pins that connect the OCM to the vehicle electrical system through dedicated take outs and connectors of the passenger side front seat wire harness. The OCM and all of the other components of the Occupant Classification System (OCS) including the passenger side front seat, the seat weight sensors, and the seat adjusters, cushion, back, frame, foam, springs, and wiring harness are a factory-calibrated and assembled unit. Any time any one of these components is removed or replaced for any reason, the OCM must be re-calibrated using a diagnostic scan tool, the Occupant Classification Seat Weight special tool, and the Occupant Classification System Verification Test. Refer to the appropriate diagnostic procedures. The OCM cannot be adjusted or repaired and, if damaged or ineffective, it must be replaced. The OCM software is flash programmable. A non-calibrated OCM is available for separate service replacement.
Occupant Classification Module - Installation5 steps
⚠ WARNING
To avoid serious or fatal injury on vehicles equipped with airbags, disable the Supplemental Restraint System (SRS) before attempting any steering wheel, steering column, airbag, Occupant Classification System (OCS), seat belt tensioner, impact sensor or instrument panel component diagnosis or service. Disconnect and isolate the battery negative (ground) cable, then wait two minutes for the system capacitor to discharge before performing further diagnosis or service. This is the only sure way to disable the SRS. Failure to follow these instructions may result in accidental airbag deployment.
ℹ NOTE
A non-calibrated Occupant Classification Module (OCM) is available for separate service replacement. The OCM and all of the other components of the Occupant Classification System (OCS) including the passenger side front seat, the seat weight sensors, and the passenger seat adjusters, cushion, back, frame, foam, springs, and wiring harness are a factory-calibrated and assembled unit. Any time any one of these components is removed or replaced for any reason, the OCM must be re-calibrated using a diagnostic scan tool, the Occupant Classification Seat Weight special tool, and the Occupant Classification System Verification Test. Refer to the appropriate diagnostic procedures.
Fig. 1
Fig. 1
  1. Reach under the front edge of the passenger side front seat cushion to carefully position the Occupant Classification Module (OCM) (1) to the top of the mounting bracket (4) on the inboard passenger side front seat riser (2). When the OCM is correctly positioned, the connector receptacles on the module will be pointed forward.
  2. Install and tighten the two screws (3) that secure the OCM to the mounting bracket. Tighten the screws to 2 Nm (20 in. lbs.).
  3. Reconnect the two seat wire harness connectors to the OCM connector receptacles located on the forward-facing end of the module. Be certain that the latches on each connector are fully engaged.
  4. Do not reconnect the battery negative cable at this time. The Supplemental Restraint System (SRS) Verification Test procedure should be performed following service of any SRS component. Service and Repair.
  5. Following successful completion of the SRS Verification Test procedure, perform the Occupant Classification System Verification Test using a diagnostic scan tool. Refer to the appropriate diagnostic procedures.
Occupant Classification Module - Removal4 steps
⚠ WARNING
To avoid serious or fatal injury on vehicles equipped with airbags, disable the Supplemental Restraint System (SRS) before attempting any steering wheel, steering column, airbag, Occupant Classification System (OCS), seat belt tensioner, impact sensor or instrument panel component diagnosis or service. Disconnect and isolate the battery negative (ground) cable, then wait two minutes for the system capacitor to discharge before performing further diagnosis or service. This is the only sure way to disable the SRS. Failure to follow these instructions may result in accidental airbag deployment.
ℹ NOTE
A non-calibrated Occupant Classification Module (OCM) is available for separate service replacement. The OCM and all of the other components of the Occupant Classification System (OCS) including the passenger side front seat, the seat weight sensors, and the passenger seat adjusters, cushion, back, frame, foam, springs, and wiring harness are a factory-calibrated and assembled unit. Any time any one of these components is removed or replaced for any reason, the OCM must be re-calibrated using a diagnostic scan tool, the Occupant Classification Seat Weight special tool, and the Occupant Classification System Verification Test. Refer to the appropriate diagnostic procedures.
Fig. 1
Fig. 1
  1. Disconnect and isolate the battery negative cable. Wait two minutes for the system capacitor to discharge before further service.
  2. Reach under the front edge of the passenger side front seat cushion to access and disconnect the two seat wire harness connectors from the Occupant Classification Module (OCM) (1) connector receptacles located on the forward-facing end of the module.
  3. Remove the two screws (3) that secure the OCM to the top of the mounting bracket (4) on the inboard passenger side front seat riser (2).
  4. Remove the OCM from under the passenger side front seat cushion.
Occupant Classification Module - Descriptionreference
Fig. 1
Fig. 1
DESCRIPTION The Occupant Classification Module (OCM) (1) is secured with two screws to a stamped metal bracket on the inboard passenger side front seat riser beneath the seat cushion. Concealed within a hollow in the center of the molded plastic OCM housing is a microprocessor and the other electronic circuitry of the module. The module housing is sealed to enclose and protect the internal electronic circuitry. Four mounting tabs (2) and two connector receptacles (3) are integral to the OCM housing. The two mounting tabs designed to accept self tapping screws are used to secure the module to the mounting bracket, while the remaining two mounting tabs are unused in this application. The connector receptacles contain terminal pins that connect the OCM to the vehicle electrical system through dedicated take outs and connectors of the passenger side front seat wire harness. The OCM and all of the other components of the Occupant Classification System (OCS) including the passenger side front seat, the seat weight sensors, and the seat adjusters, cushion, back, frame, foam, springs, and wiring harness are a factory-calibrated and assembled unit. Any time any one of these components is removed or replaced for any reason, the OCM must be re-calibrated using a diagnostic scan tool, the Occupant Classification Seat Weight special tool, and the Occupant Classification System Verification Test. Refer to the appropriate diagnostic procedures. The OCM cannot be adjusted or repaired and, if damaged or ineffective, it must be replaced. The OCM software is flash programmable. A non-calibrated OCM is available for separate service replacement.
Factory service manual
From the 2008 KK factory manual — descriptions, specs, torque & procedures for this part.
OCCUPANT CLASSIFICATION MODULE📷 1
The Occupant Classification Module (OCM) (1) is secured with two screws to a stamped metal bracket on the inboard passenger side front seat riser beneath the seat cushion. Concealed within a hollow in the center of the molded plastic OCM housing is a microprocessor and the other electronic circuitry of the module. The module housing is sealed to enclose and protect the internal electronic circuitry.
Four mounting tabs (2) and two connector receptacles (3) are integral to the OCM housing. The two mounting tabs designed to accept self tapping screws are used to secure the module to the mounting bracket, while the remaining two mounting tabs are unused in this application. The connector receptacles contain terminal pins that connect the OCM to the vehicle electrical system through dedicated take outs and connectors of the passenger side front seat wire harness.
The OCM and all of the other components of the Occupant Classification System (OCS) including the passenger side front seat, the seat weight sensors, and the seat adjusters, cushion, back, frame, foam, springs, and wiring harness are a factory-calibrated and assembled unit. Any time any one of these components is removed or replaced for any reason, the OCM must be re-calibrated using a diagnostic scan tool, the Occupant Classification Seat Weight special tool, and the Occupant Classification System Verification Test. Refer to the appropriate diagnostic procedures.
The OCM cannot be adjusted or repaired and, if damaged or ineffective, it must be replaced. The OCM software is flash programmable. A non-calibrated OCM is available for separate service replacement.
figure
OCCUPANT CLASSIFICATION MODULE📷 1
The microprocessor in the Occupant Classification Module (OCM) contains the Occupant Classification System (OCS) logic circuits. The OCM uses On-Board Diagnostics (OBD) and can communicate with other electronic modules in the vehicle as well as with the diagnostic scan tool using the Controller Area Network (CAN) data bus. This method of communication is also used for OCS diagnosis and testing through the 16-way data link
connector located on the driver side lower edge of the instrument panel.
The OCM provides voltage to the four seat weight sensors located on the corners of the passenger side front seat. The OCM then monitors return inputs from each of the sensors on dedicated hard wired data communication circuits. The seat weight sensor inputs allow the OCM to determine whether the passenger side front seat is occupied and the relative size of the occupant by providing a weight-sensing reference to the load on the seat.
Pre-programmed decision algorithms and OCS calibration allow the OCM microprocessor to determine when passenger airbag protection is appropriate based upon the seat load as signaled by the seat weight sensors. When the programmed conditions are met, the OCM sends the proper electronic occupant classification messages over the CAN data bus to the Occupant Restraint Controller (ORC), and the ORC controls the deployment circuits for the passenger side front supplemental restraints. On vehicles so equipped, the ORC also provides a control output for the passenger airbag on/off indicator in the instrument panel based upon the electronic occupant classification messages it receives from the OCM.
The OCM microprocessor continuously monitors all of the OCS electrical circuits and components to determine the system readiness. If the OCM detects a monitored system fault, it sets an active and stored Diagnostic Trouble Code (DTC) and sends the appropriate electronic messages to the ORC over the CAN data bus. Then the ORC sets a DTC and sends messages to control the airbag indicator operation accordingly. An active fault only remains for the duration of the fault, or in some cases for the duration of the current ignition switch cycle, while a stored fault causes a DTC to be stored in memory by the OCM and the ORC. For some DTCs, if a fault does not recur for a number of ignition cycles, the OCM will automatically erase the stored DTC. For other internal faults, the stored DTC is latched forever.
The OCM receives battery current on a fused B(+) circuit through a fuse in the Totally Integrated Power Module (TIPM) and receives electronic ignition switch status messages indicating the ignition switch position over the CAN data bus. The OCM receives ground through a ground circuit and take out of the body wire harness. These connections allow the OCM to be operational whenever the ignition switch is in the ON or START positions.
The hard wired inputs and outputs for the OCM may be diagnosed using conventional diagnostic tools and procedures. Refer to the appropriate wiring information. However, conventional diagnostic methods will not prove conclusive in the diagnosis of the OCM or the electronic controls and communication between other modules and devices that provide features of the OCS. The most reliable, efficient, and accurate means to diagnose the OCM or the electronic controls and communication related to OCM operation requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.
figure
OCCUPANT CLASSIFICATION MODULE
WARNING: To avoid serious or fatal injury on vehicles equipped with airbags, disable the Supplemental Restraint System (SRS) before attempting any steering wheel, steering column, airbag, Occupant Classification System (OCS), seat belt tensioner, impact sensor, or instrument panel component diagnosis or service. Disconnect and isolate the battery negative (ground) cable, then wait two minutes for the system capacitor to discharge before
performing further diagnosis or service. This is the only sure way to disable the SRS. Failure to take the proper precautions could result in accidental airbag deployment.
NOTE: A non-calibrated Occupant Classification Module (OCM) is available for separate service replacement. The OCM and all of the other components of the Occupant Classification System (OCS) including the passenger side front seat, the seat weight sensors, and the passenger seat adjusters, cushion, back, frame, foam, springs, and wiring harness are a factory-calibrated and assembled unit. Any time any one of these components is removed or replaced for any reason, the OCM must be re-calibrated using a diagnostic scan tool, the Occupant Classification Seat Weight special tool, and the Occupant Classification System Verification Test. Refer to the appropriate diagnostic procedures.
Screws & Mounting Bracket
1. Disconnect and isolate the battery negative cable. Wait two minutes for the system capacitor to discharge before further service. 2. Reach under the front edge of the passenger side front seat cushion to access and disconnect the two seat wire harness connectors from the Occupant Classification Module (OCM) (1) connector receptacles located on the forward-facing end of the module. 3. Remove the two screws (3) that secure the OCM to the top of the mounting bracket (4) on the inboard passenger side front seat riser (2). 4. Remove the OCM from under the passenger side front seat cushion.
OCCUPANT CLASSIFICATION MODULE📷 2
WARNING: To avoid serious or fatal injury on vehicles equipped with airbags, disable the Supplemental Restraint System (SRS) before attempting any steering wheel, steering column, airbag, Occupant Classification System (OCS), seat belt tensioner, impact sensor, or instrument panel component diagnosis or service. Disconnect and isolate the battery negative (ground) cable, then wait two minutes for the system capacitor to discharge before performing further diagnosis or service. This is the only sure way to disable the SRS. Failure to take the proper precautions could result in accidental airbag deployment.
NOTE: A non-calibrated Occupant Classification Module (OCM) is available for separate service replacement. The OCM and all of the other components of the Occupant Classification System (OCS) including the passenger side front seat, the seat weight sensors, and the passenger seat adjusters, cushion, back, frame, foam, springs, and wiring harness are a factory-calibrated and assembled unit. Any time any one of these components is removed or replaced for any reason, the OCM must be re-calibrated using a diagnostic scan tool, the Occupant Classification Seat Weight special tool, and the Occupant Classification System Verification Test. Refer to the appropriate diagnostic procedures.
Screws & Mounting Bracket
1. Reach under the front edge of the passenger side front seat cushion to carefully position the Occupant Classification Module (OCM) (1) to the top of the mounting bracket (4) on the inboard passenger side front seat riser (2). When the OCM is correctly positioned, the connector receptacles on the module will be pointed forward. 2. Install and tighten the two screws (3) that secure the OCM to the mounting bracket. Tighten the screws to 2 N.m (20 in. lbs.). 3. Reconnect the two seat wire harness connectors to the OCM connector receptacles located on the
forward-facing end of the module. Be certain that the latches on each connector are fully engaged. 4. Do not reconnect the battery negative cable at this time. The Supplemental Restraint System (SRS) verification test procedure should be performed following service of any SRS component. See

Standard procedure

5
Following successful completion of the SRS verification test procedure, perform the Occupant
Classification System Verification Test using a diagnostic scan tool. Refer to the appropriate diagnostic procedures. OCCUPANT RESTRAINT CONTROLLER
figure
figure