Turn Signal Lamps
The turn signals can be activated using the left stalk switch input to the Steering Column Control Module (SCCM) which sends the command to the BCM over the CAN-C bus. When the turn signal lamps are switched on, the BCM activates a CAN-IHS signal corresponding to the selected side with a blinking scheme and synchronous to the lights activation. At the same time that the turn signal lights are switched ON, the BCM also activates internal signals that are active for the length of the turn signal event.
The left or right direction signals are activated using the left stalk switch input to the SCCM. These commands are codified using a resistive divider, into the analogical command that is read by the SCCM and then sent to the BCM over CAN-C.
The turn signal lamps system includes the multi-function switch on the steering column, the SCCM, the IPC and the BCM. The front turn signal lamp bulbs each have a path to ground at all times through their connection to the combination park/turn lamp and dash wire harness. The combination park/turn lamp and dash wire harness has takeouts with eyelet terminals that are secured to the body sheet metal. The rear turn signal lamps are LED elements within the rear outer tail lamp housing.
The SCCM monitors a hardwired multiplex input from the multi-function switch to determine the status of the turn signal switch, then sends the appropriate electronic turn signal switch status messages to the BCM over the CAN data bus. The BCM responds to these messages by controlling a battery voltage output and the flash rate for either the right or left turn signal lamps through high side drivers on the appropriate front and rear, right or left turn signal control circuits. The BCM also sends the appropriate electronic messages to the IPC to control the illumination and flash rate of the right or left turn signal indicators, as well as to control the click rate of an electromechanical relay soldered onto the IPC electronic circuit board that emulates the sound emitted by a conventional electromechanical turn signal flasher.
The BCM also provides a Turn Signal ON warning that will send a request message to the IPC over the CAN bus that causes the IPC to generate repetitive chimes to indicate that a turn signal has been active continuously for 1.6 km (1 mile) with the vehicle speed greater than 22 km/h (15 mph). The chime will continue until the turn signal input becomes inactive or until the vehicle speed message indicates that the speed is less than 22 km/h (15 mph), whichever occurs first.
Exterior Mirror Signaling - If the vehicle is equipped with turn signals in the outside rearview mirrors, the BCM sends a CAN-C message to the respective door module to flash the signal in the lamp in accordance to the same signal used to drive the lamp turn signal indicators.
Lane Change Function - If either of the turn signals are actuated for a time equal to or less than 500 ms, the BCM will activate the requested turn signal light and will blink for three blinks. At the same time the signals are switched ON, the BCM will also activate the internal signal corresponding with the selected side. The internal signal will show ON for the entire period of the turn signal even and will not show to be blinking. The internal signal is synchronous with the signal activation and will turn OFF at the end of the vent. After 3 blink cycles, the BCM switches OFF the turn signals, the CAN-IHS signals, and the internal signals corresponding to the selected side.
Remote Lock/Unlock Turn Signal Flash - The BCM receives a request from the Radio Frequency Hub (RFH) module indicating that either a remote lock or a remote unlock request has occurred. The BCM checks the status of the customer programmable features to determine if the option to flash the signals is ON or OFF. If this option is enabled by the driver, the BCM will flash the turn signals upon a valid RFH module signal being received. For unlocking requests, the BCM will flash all turn signals for two blinks. For locking requests the BCM will flash all turn signals for one blink. The default for the customer programmable feature for "Flash Lamps with Lock" is set to ON.
Remote Open/Close Liftgate Turn Signal Flash - When the BCM receives a CAN-C signal from the RFH module indicating a remote liftgate Open/Close or Passive Entry request event has occurred, the BCM will flash all vehicle turn signals for two blink cycles. When the BCM receives the CAN-IHS signal from the Power Liftgate Module (PLGM) indicating the liftgate is closing or opening, the BCM will flash all turn signals for two blink cycles.
Remote Start Turn Signal Flash - When an internal signal from the RFH module indicates that a remote start event has been requested, the BCM will activate the turn signals for one blink cycle.
SNA Definition - Signal Not Acquired (SNA). If the SCCM detects an issue (stuck switch, and others) and sets an active fault, the SCCM shall broadcast the SNA state to the BCM. BCM will default to an idle state and keep all turn signal outputs OFF until a valid request is received.
Turn Signal Alert Feature - When either the left or right turn signal are activated, the IPC will record the distance travelled using odometer information by way of the CAN-IHS signal. When one mile (1.6 km) has been traveled, the cluster will assume that the operator has unintentionally left the turn signals activated and two alerts will occur: A slow audible chime will emit from the cluster or an icon and textual message will display on the cluster.