Blind Spot Monitor System: Notes

The primary components of the Blind Spot Monitor (BSM) system are the microcontroller based Electronic Control Units (ECU) integral to each of the two Radio Detection And Ranging (RADAR) sensors, one behind each outboard side of the rear bumper fascia. Each ECU operates on battery current received from a fuse in the interior Power Distribution Center (PDC) whenever the status of the ignition switch is On, and the ECU has a path to ground at all times through a take out and eyelet terminal of the body wire harness that is secured to the body sheet metal. Each of these ECU communicate with each other as well as with other electronic modules in the vehicle over the Controller Area Network (CAN) data bus network.

The BSM system ECU continually monitor all of the BSM system circuits and components for readiness, and will store a Diagnostic Trouble Code (DTC) for any fault that is detected. The ECU also communicate with a diagnostic scan tool over the CAN data bus. When a BSM system ECU stores a DTC, it sends an electronic request message to the Electronic Vehicle Information Center (EVIC) in the Instrument Panel Cluster (IPC) and a SERVICE BLIND SPOT SYSTEM  or BLIND SPOT SYSTEM TEMPORARILY UNAVAILABLE  textual message is displayed by the EVIC to alert the vehicle operator.

The BSM system ECU also monitor electronic messages received over the CAN data bus from the Radio indicating the customer programmable features settings for the BSM system. The BSM system ECU receive and analyze data inputs directly from the radar sensors, calculate and provide the proper hardwired outputs to illuminate the visual alert displays in their respective right or left outside rear view mirrors, as well as calculate and communicate the proper audible alert output requests to the Radio over the CAN data bus.

The BSM radar sensors allow the BSM system ECU to locate and identify nearby objects of interest meeting the criteria established by algorithms within the system software. The BSM displays provide the vehicle operator with a visual alert indicating that an object of interest has been detected within one of the vehicle detection zones. The BSM audible alerts are then issued by the Radio through the appropriate audio system speakers based upon electronic audible alert request  messages received from the BSM system ECU. The BSM system ECU also send electronic radio mute request  messages over the CAN data bus to the Radio whenever an audible alert is requested. This message activates the radio mute function while the audible alert is being sounded, then resumes normal radio function when the alert is completed.

However, conventional diagnostic methods will not prove conclusive in the diagnosis of the BSM system or the electronic controls and communication between ECU and other devices that provide some features of this system. The most reliable, efficient and accurate means to diagnose the BSM system or the ECU and communication related to BSM system operation requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.