Turn Signal Indicators

The turn signal indicator indicates the turn signal (left or right indicator flashing) or hazard warning (both left and right indicators flashing) have been selected and are operating. These indicators are controlled by transistors on the IPC electronic circuit board based upon the IPC programming and electronic messages received from the BCM over the CAN data bus.

Each turn signal indicator LED is completely controlled by the IPC logic circuit, and that logic will allow this indicator to operate whenever the IPC receives a battery current input on the fused B(+) circuit. Therefore, each LED can be illuminated regardless of the ignition switch position. The LED only illuminates when it is provided a path to ground by the IPC transistor. The IPC will turn ON the turn signal indicators for the following reasons:

• Turn Signal Indicator Lamp-On Message  - The IPC receives an electronic right  or left turn signal-ON  message from the multifunction switch over the LIN data bus. The IPC transmits the request across the CAN Bus to the BCM and the appropriate turn signal indicator will be flashed ON and OFF. The BCM then sends the appropriate electronic message to the IPC to control the flash rate of the selected turn signal indicators, as well as to control the click rate of an electromechanical relay soldered onto the IPC electronic circuit board. The turn signal indicators continue to flash ON and OFF until the IPC receives a lamp-OFF message from the BCM, or until the ignition switch is turned to the OFF position.
• Hazard Warning Indicator Lamp-On Message  - The IPC receives an electronic hazard warning-ON  message from the multifunction switch across the LIN data bus. The IPC will transmit this request to the BCM and the BCM then sends the appropriate electronic messages to the IPC to control the flash rate of the right and 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 hazard warning flasher. The turn signal indicators continue to flash ON and OFF until the IPC receives a hazard warning-OFF message from the BCM.
• Lamp Out Mode  - If the BCM detects an inoperative turn signal lamp or circuit, the flash rate for the remaining operative turn signals increases and an electronic message is also sent to the IPC. The IPC also increases the flash rate of the turn signal indicators and the click rate of the electromechanical relay to provide an indication of the problem to the vehicle operator.

The IPC continually monitors the electronic messages from the BCM to determine the proper turn signal and hazard warning indicator operation.