System Outline

WARNING: This page is about a different car, the 2008 Lexus LS 600hL. However, it is still accessible from the selected car via links, so may be relevant.

* In the pre collision seat belt system(PSB), the seat belt is retracted by a motor to optimize the restraint performance when it receives the appropriate signals from the pre collision sensor (millimeter wave radar sensor assembly + driving support ECU assembly) or skid control ECU assembly.

* The skid control ECU assembly sends trigger signals to the seat belt control ECU through CAN communication when it detects certain vehicle conditions such as a spin, under steer or sudden braking. The seat belt control ECU activates the PSB upon receiving a trigger signal.

* The pre collision sensor detects an on coming vehicle or object on the road ahead using the millimeter wave radar and determines in advance whether a collision is unavoidable. It makes this decision based on information from the driving support ECU assembly such as the position, speed and on coming route of the object. The driving support ECU assembly then sends a signal to the seat belt control ECU through CAN communication to activate the PSB motor and retract the seat belt before a crash. This function will activate even when the vehicle speed is 0 km/h if the situation warrants it.

* When the pre collision system (PCS) has a failure, the message 'CHECK PCS SYSTEM' is shown on the multi information display on the combination meter. The PCS warning light is then lit up. When the system is not available due to dirt on the radar, the message 'PCS NOT AVAILABLE NOW' is displayed and the warning light blinks.