The Occupant Classification System (OCS) is designed to classify the weight of the front seat passenger and automatically turn OFF the front passenger air bag under certain conditions. The following article is intended to help clarify OCS function that pertains to the diagnosis and evaluation of the 2-sensor Occupant Classification System (OCS) utilized in some Nissan and Infiniti vehicles.
Current Applicable Models* in effect at the time of publication: 2013 JX (L50), 2014 QX60 (L50), 2014 QX60 Hybrid (L50), 2014 Q50 (V37), 2014 Q50 Hybrid (V37), 2013–2015 Altima (L33), 2013 - 2014 Sentra (B17), 2013–2014 Pathfinder (R52), 2014 Pathfinder Hybrid (R52), 2013–2015 LEAF (ZE0), 2013–2015 NV200 (M20), 2014 NV200 Taxi (M20), 2014-2015 Rogue (T32) *Current models equipped with the 2-sensor Occupant Classification System.
System Overview
The Nissan/Infiniti Advanced Air Bag System (AABS) has dual-stage inflators. The AABS monitors information from the crash zone sensor, the Air Bag Control Unit (ACU), the seat belt buckle sensors and the occupant classification sensors. Inflator operation is based on the severity of a collision and seat belt usage of the driver. For the front passenger seat, the occupant classification system utilizes sensors that are also monitored.
Status Light
The front passenger air bag status light is located on the instrument panel. After the ignition switch is placed in the ON position, the front passenger air bag status light on the instrument panel illuminates for about 7 seconds and then turns off or illuminates depending on the front passenger seats occupied status. If the passenger seat is unoccupied, the front passenger air bag status light is OFF, and the air bag is OFF and will not inflate in a crash. If the front passenger seat is occupied by a passenger that meets the conditions in accordance with the U.S. regulations, the air bag status light is OFF to indicate that the front passenger air bag is operational (ON). If the front passenger air bag status light illuminates, it indicates that the front passenger air bag is OFF and will not inflate in a crash.
Occupant Classification Sensors
The 2-sensor Occupant Classification System utilizes strain gauge type weight sensors. They are designed to classify the weight of the front seat passenger and automatically turn the passenger air bag OFF when the vehicle is operated under certain conditions as described by U.S. regulations. The purpose of the regulations is to help reduce the risk of injury or death from an inflating air bag to certain front passenger seat occupants. When the ignition switch is placed in the ON position, the occupant classification sensors require a few seconds to classify the front passenger seat occupied status. The OCS 2-sensor strain gauge sensors are located on a part of the front passenger seat frame assembly.
NOTE: Classification is primarily done while the vehicle is at idle and not moving. This is the best condition to accurately classify the front passenger seats occupied status in vehicles equipped with the strain gauge sensors.
Normal Operation
Even with advanced air bags, seat belts should be correctly worn and the passenger seated upright in the front passenger seat. Adult occupants who are properly seated and correctly using the seat belt should not cause the passenger air bag to be automatically turned OFF. Passengers need to be seated upright and as far as practical away from the instrument panel and wearing the seat belt properly for the most effective protection by the seat belt and the supplemental air bag.
NOTE: See the Safety section (Section 1) of the Owner’s Manual for safety, seats, seat belts and supplemental restraint system information. Safety section (Section 1) also has a detailed description of how the occupant classification system is designed to operate in accordance with Federal regulations.
Some issues described by customers about their OCS function may actually indicate normal operation. For example:
- If a child restraint must be used in the front passenger seat, the passenger air bag status light may or may not illuminate, depending on the size of the child and the type of child restraint being used. If a child is in the front passenger seat, the Advanced Air Bag System is designed to turn the passenger air bag OFF in accordance with regulations. If a child restraint of the type specified in the regulations is on the seat, its weight and the child’s weight can be detected by the occupant detection sensors. If the child’s weight combined with that of the child restraint can be detected, the air bag status light will illuminate to indicate the air bag is turned OFF and will not inflate in a crash. If the air bag status light is not illuminated, it is indicates that the air bag might inflate in a crash. What to do? It could be that the child restraint or seat belt is not being used properly. Make sure that the child restraint is installed properly as outlined in the Safety section (Section 1) of the vehicle’s Owner’s Manual. Make sure that the seat belt is being used properly and the child restraint is positioned properly. If necessary, move the seat to the rearmost position and adjust or remove the head restraint/headrest to obtain the correct child restraint fit. If the passenger air bag status light will not illuminate even though you believe that the child restraint and the seat belt are properly positioned, the system may be sensing an unoccupied seat (in which case the air bag is OFF). If the passenger air bag status light is still not illuminated, reposition the occupant and the child restraint in the rear seat. Verify the operation of the 2-sensor OCS with CONSULT.
- If an occupant is in the seat but the passenger air bag status light is illuminated (indicating the air bag is OFF), it could mean that the front seat passenger is a person of small, physical stature. The occupant may be taking his/her weight off the seat cushion (for example, by leaning forward or not sitting upright, by sitting on the edge of the seat, or by otherwise being out of position) or may not be using the seat belt properly. These conditions could cause the sensor to turn the air bag OFF. What to do? Urge the customer to review the Owner’s Manual. However, the system may need to be serviced if the size of the front passenger seat occupant meets the conditions described in the Owner’s Manual and is in accordance with U.S. regulations, and the front passenger air bag status light remains illuminated. Assist the customer in understanding appropriate seating posture and seat belt usage, which will facilitate correct OCS operation. If a small adult, pre-teen or child is sitting in the passenger seat and the passenger air bag light intermittently is OFF and then ON, the system may be sensing an unoccupied seat (in which case the air bag is OFF). Make sure that the seat belt is used properly and the occupant is positioned properly. If the air bag status light is not illuminated, confirm the air bag is working properly. Instruct the customer that Nissan recommends pre-teens and children to be properly restrained in the rear seating positions.
- If the front passenger seat is not occupied, the front passenger air bag status light will not illuminate and the passenger air bag is designed not to inflate in a crash. However, heavy objects placed on the seat could result in front passenger air bag inflation during a crash because of the objects’ weight being detected by the occupant classification sensor. What to do? Urge the customer to review Section 1 of the vehicle’s Owner’s Manual and properly store and secure heavy objects in the cargo area.
- Other conditions could also result in air bag inflation, such as a child standing on the seat or if two children are on the seat. Urge the customer to review the Owner’s Manual precautions for proper seating and seat belt usage.
Other conditions could result in complaints of the air bag status light illuminating and shutting OFF intermittently:
- If a large adult who is sitting in the passenger seat exits the vehicle, the front passenger air bag status light will go from OFF to ON for a few seconds and then turn OFF.
- If the vehicle is stationary and a passenger of small stature jumps in and occupies the front passenger seat and the vehicle starts moving right away, the front passenger air bag status light may illuminate and go from OFF to ON intermittently for a few seconds and then turn OFF. What to do? Inform the customer that the air bag system and the front passenger air bag status light will take a few seconds to register a change in the passenger seats status in vehicles equipped with the strain gauge sensors. Let them know that the front passenger seat occupant needs to be in the proper seating position and his or her seat belt being used (as described in the vehicle’s Owner’s Manual) for up to 30 seconds to allow the system to classify the passenger before the vehicle is put into motion. It is important that he or she confirms that the passenger is properly classified prior to driving. Maximum fan speed can increase the time required for classification. If there are customer concerns about the system taking longer than anticipated to classify the front passenger during a stopped condition, please suggest decreasing A/C fan speed until the classification is complete. The customer can check the classification by using the front passenger air bag status light. The best condition to classify the front passenger seat’s occupied status is to allow time for the system to classify the front passenger before pulling away from a stopped condition.
Suggested Repair Information for the 2-sensor OCS
NOTE: To verify and understand the operation of the 2-sensor OCS, including those vehicles with the R1405 recall already performed, refer to the NTB14-084 or ITB14-042 in ASIST.
NOTE:
- The 13MY JX and Pathfinder and all model years of NV200 do not support a B00A0-00 DTC (light will flash without setting DTC). If the air bag light flashes for this model (first confirm that the vehicle is not in diagnostic mode), please replace the OCS sensors and the OCS C/U and perform a zero point reset.
- If there is a Passenger Air Bag Indicator (PABI) light only issue WITHOUT DTCs, replacement of the OCS C/U or the ACU is not required.
Suggested Repair Procedure
Sequence 1
- Replace OCS sensors at the lowest possible service part level (this may be the lower seat frame or full passenger seat depending upon the model).
- Please note the seat bolts need to be torqued to specification.
- Perform zero point reset.
- Return to Service Manual procedures.
Sequence 2
- Replace OCS C/U.
- Perform zero point reset.
Sequence 3
- Follow Service Manual procedures.
Zero point reset is an initializing procedure for the OCS (weight) sensors that must be performed using CONSULT when removing and installing the passenger seat or servicing the OCS system. Please note that the air bag data monitor in CONSULT will indicate the front passenger air bag status in real-time.
Always perform zero point reset using CONSULT when removing and installing the front passenger seat or servicing the occupant classification system (OCS). If zero point reset is not performed, the OCS may not operate normally, which may increase the risk of serious injury in a crash.
