Blind Spot Monitoring System - Operation

BLIND SPOT MONITOR SYSTEM

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 Totally Integrated Power Module (TIPM) (also known as the Forward Control Module/FCM) 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 ElectroMechanical Instrument Cluster (EMIC) (also known as the Cab Compartment Node/CCN) 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 EVIC 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 hard wired 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 Receiver Module (RRM) over the CAN data bus.

In vehicles manufactured for certain export markets, the BSM ECU will automatically disable the BSM radar sensors whenever the vehicle is being operated near radio astronomy towers. The ECU integral to each radar sensor stores a list of known tower locations and compares that listing to Global Positioning Satellite (GPS) signal data received over the CAN data bus from the on-board navigation system. When the vehicle enters a restricted zone, the ECU each disable their respective radar sensor, turn on the amber visual icons in the BSM displays and send electronic messages to the EVIC to display a BSM NOT AVAILABLE textual message to alert the vehicle operator. When the vehicle exits the restricted zone, the BSM ECU automatically extinguish the warnings and restore radar sensor operation.

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. The BSM system ECU also send 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 or 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.

STANDBY MODE

The Blind Spot Monitor (BSM) system remains in standby mode as long as the park brake is applied in a vehicle with a manual transmission, or while the automatic transmission gear selector lever is in the Park (P) position. In the standby mode the system receives vehicle information, responds to changes in customer programmable features settings received through the Electronic Vehicle Information Center (EVIC) in the ElectroMechanical Instrument Cluster (EMIC) (also known as the Cab Compartment Node/CCN) and can perform limited self-diagnostics indicating hard system fault conditions.

REAR CROSS PATH MODE

Unless disabled in the customer programmable features settings received through the Electronic Vehicle Information Center (EVIC), the Blind Spot Monitor (BSM) system provides a feature called Rear Cross Path (RCP) mode. The RCP mode is active only when the transmission gear selector (manual or automatic) is in the Reverse (R) position. The RCP mode is intended to aid the driver when backing out of parking spaces where vision of vehicles crossing laterally through the rear path of the host vehicle may be blocked. The host vehicle must proceed slowly and cautiously out of the parking space until the rear end of the vehicle is exposed. The BSM radar sensors will then have a clear view of the crossing traffic and, if an oncoming vehicle (object of interest) is detected, will generate visual and audible alerts to the operator of the host vehicle.

The BSM system monitors the rear detection zones on both sides of the vehicle for objects that are moving toward the side of the vehicle with speeds of from 1 to 3 kilometers-per-hour (1 to 2 miles-per-hour) up to 35 kilometers-per-hour (22 miles-per-hour), such as typically encountered in parking lot situations. In vehicles equipped with the BSM option, the RCP mode is enabled from the factory as a default. The RCP mode can be manually disabled and enabled by the vehicle operator using the customer programmable features option of the EVIC.

The RCP mode normally uses the same BSM system customer programmable features settings. However, the RCP mode will always include the audible alert feature, even if it was disabled for the BSM mode using the EVIC customer programmable features settings. The audible alert can not be deactivated for the RCP mode. The RCP mode visual alert is illuminated only in the display located on the same side of the vehicle where the object of interest is detected. Likewise, the RCP mode repeating short audible alert is issued only through the audio system speakers located on the same side of the vehicle where the object of interest is detected.

BLIND SPOT MONITOR MODE

Unless disabled in the customer programmable features settings received through the Electronic Vehicle Information Center (EVIC), the Blind Spot Monitor (BSM) mode is active only when the manual transmission gear selector is in a position other than Reverse (R) or the automatic transmission gear selector is in a position other than Reverse (R) or Park (P). The BSM mode is intended to provide a visual alert to the driver when a target vehicle (object of interest) is located in the lane adjacent to and just behind either outside rear view mirror (the detection zone), in the blind spot area where vision of target vehicles may be inhibited by the rear structure of the host vehicle. If a turn signal is activated in the host vehicle in the same direction as that in which the target vehicle is located, a single audible alert tone will also be generated. The audible alerts of the BSM mode are not active unless the turn signal is activated.

The width of the BSM mode detection zone covers one traffic lane over on each side of the host vehicle, approximately 4.0 meters (13 feet). The length of the BSM mode detection zone starts at the outside rear view mirror and extends approximately 4.5 meters (15 feet) rearward from the rear edge of the rear fascia. The BSM mode visual alerts are activated immediately if an object of interest is within the detection zone and meets the warning criteria. However, the BSM system will not activate these alerts if:

- The object of interest (target vehicle) comes from the rear of the detection zone and passes the host vehicle at a speed greater that 50 kilometers-per-hour (31 miles-per-hour).

- The object of interest (target vehicle) enters the detection zone from the front and remains in the zone for less than 1.5 seconds.

- The object of interest (target vehicle) passes through the detection zone with a relative speed greater than 20 kilometers-per-hour (12 miles-per-hour).

- The object of interest (target vehicle) passes the host vehicle from the opposite direction.

The BSM mode audible alert may be deactivated if the operator prefers using the customer programmable features settings within the EVIC. The BSM mode can be configured for visual and audible alerts, visual alerts only or for the entire BSM system (including Rear Cross Path/RCP mode) to be turned OFF.