Blind Spot Monitor System: Notes

WARNING: This page is about a different car, the 2015 Chrysler 300. However, it is still accessible from the selected car via links, so may be relevant.

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. The two sensors are known as the Right Blind Spot Sensor (RBSS) and the Left Blind Spot Sensor (LBSS). Each ECU operates on battery current received from a fuse in the Power Distribution Center (PDC) whenever the status of the ignition switch is On. Each 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. These ECU communicate with each other, with other electronic modules in the vehicle or with a diagnostic scan tool over the Controller Area Network (CAN) - Interior High Speed (IHS) data bus network.

Each BSM system ECU continually monitors its own BSM system circuits and components for readiness, and will store a Diagnostic Trouble Code (DTC) for any fault that is detected. When a BSM system ECU stores a DTC, it sends an electronic request message to the Instrument Cluster (IC) (also known as the Common Instrument Cluster/CIC). The IC will then display a SERVICE BLIND SPOT SYSTEM or BLIND SPOT SYSTEM TEMPORARILY UNAVAILABLE textual message in the Electronic Vehicle Information Center (EVIC) to alert the vehicle operator.

The Powernet network architecture used in this vehicle includes the Body Control Module (BCM) (also known as the Common Body Controller), which is also a CAN bus gateway and will relay messages received on the CAN-IHS data bus to the IC over the CAN-C data bus. The BSM system ECU sends request messages via the CAN-IHS bus to the BCM. Each BSM system ECU also monitors electronic messages received over the CAN-IHS data bus from the Radio Receiver Module (RRM) (also known as the radio or the head unit) through the CAN-C bus via the BCM gateway indicating the customer programmable features settings for the BSM system.

Each BSM system ECU receives and analyzes data inputs directly from its own radar sensor, calculates and provides the proper electronic messages over the CAN-IHS bus to the BCM as well as to the Driver Door Module (DDM) or Passenger Door Module (PDM). The DDM and PDM use hard wired outputs to illuminate the visual alert displays in their respective right or left outside rear view mirrors, as well as calculates and communicates the proper audible alert output requests to the RRM over the CAN bus network.

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 RRM through the appropriate audio system speakers based upon electronic audible alert request messages received from the BSM system ECU. Each BSM system ECU also sends electronic radio mute request messages over the CAN data bus to the RRM 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.

The hard wired circuits between components related to the BSM system may be diagnosed using conventional diagnostic tools and procedures. Refer to the appropriate wiring information. The wiring information includes wiring diagrams, proper wire and connector repair procedures, details of wire harness routing and retention, connector pin out information and location views for the various wire harness connectors, splices and grounds.

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.