Frontal airbags have helped to save lives and prevent many injuries; however, special care must be taken when children are sitting in the front seat. To help protect these passengers, Toyota vehicles are equipped with an Occupant Classification System (OCS) that detects the weight of the occupant in the passenger seat and disables the passenger-side front airbags if a child is seated there. Because the accuracy of the OCS can have significant consequences, Toyota has requirements for OCS calibration after a collision.
THE OCS IS COMPOSED OF:
- An Occupant Detection ECU that judges whether the front passenger seat is occupied based on signals from sensors and from the passenger seat belt buckle switch.
- Occupant Detection Sensors that send signals to the ECU in accordance with the weight of the occupant.
- A front passenger seat belt buckle switch that detects whether or not the front passenger seat belt is fastened.
- An SRS warning light that alerts the driver of a malfunction in the airbag system.
- Airbag ON/OFF indicator lights that inform the driver whether the airbags and outer belt assembly are active. In the event of a malfunction, both the Airbag OFF indicator light and the SRS warning light come on.
“Just as a bathroom scale must be properly calibrated to show your accurate weight, OCS sensors require precise zero point calibration to correctly determine the weight of the passenger,” says Eric Mendoza, Collision Repair & Refinish Training Assistant Manager, Toyota Motor Sales, U.S.A., Inc. “Toyota’s position on zero point calibration is stated in the Toyota Repair Manual. OCS calibration is an essential part of returning a vehicle to its pre-accident condition.” Toyota requires a zero point OCS calibration and sensitivity check when any of the following occurs:
- The occupant detection ECU is replaced.
- Accessories (seatback tray and seat cover, etc.) are installed.
- The front passenger seat is removed from the vehicle.
- One of the bolts used to install the front passenger seat is removed.
- The passenger airbag indicator light comes on when the front passenger seat is unoccupied.
- The vehicle is brought to the workshop for repair due to an accident or a collision.
PRECAUTIONS ARE PARAMOUNT
Anything that puts pressure on the seat can throw off the OCS reading. To ensure the accuracy of your calibration, always observe these precautions:
- Make sure that the front passenger seat is unoccupied before performing the operation.
- Park the vehicle on a level surface.
- Remove all objects from the front passenger seat.
- Do not put a heavy load in the front passenger seatback pocket or attach a seatback table to the front passenger seatback.
- Do not put objects under the front passenger seat.
- Keep the front passenger seatback as upright as possible.
- Make sure that child restraint systems installed on the rear seat never come into contact with the front seatback.
- Never kick the front passenger seat or subject it to severe impacts.
To perform the zero point calibration and sensitivity test, you will need a weight and the Toyota Techstream scan tool. Techstream provides immediate access to the detailed, model-specific OCS calibration procedure information. After you have taken all precautions, position the front passenger seat position as follows:
- Rearmost slide position
- Lowest headrest height
- Upright recline angle
Next, place the weight so that it touches the seatback. Then proceed with the following steps:
- Turn off the ignition switch.
- Connect Techstream to the DLC3 connector.
- Turn the ignition switch to ON and turn the Techstream on.
- Enter the following menus: Body Electrical/Occupant Detection/Utility/Zero Point Calibration and Sensitivity Check.
- Follow the prompts on the Techstream screen to perform the zero point calibration and sensitivity check. You will get readings of “Zero Point Calibration Is Complete” and “Sensitivity Check Is Complete” when the checks are OK.
If the zero point calibration does not complete, refer to the repair manual information for additional assistance or send the vehicle to a qualified service department for diagnosis of the problem.
When you have successfully completed zero point calibration on the Occupant Classification System, you have helped to bring the vehicle back to its original factory specifications. Thanks to Occupant Classification Systems, airbags are safer than ever. By adhering to Toyota requirements, you play a crucial role in ensuring that they work effectively—and in doing so, you are helping to protect Toyota passengers from harm.