Turn Signal Lamps

The turn signal lamps system includes the left (lighting) multi-function switch, the IPC and the BCM. The front turn signal lamp bulbs in the lower cavity of each lower front combination lamp unit. The rear turn signal lamp bulbs have a path to ground at all times through a takeout and eyelet terminal of the body wire harness that is secured by a screw to the body sheet metal within the passenger compartment.

The BCM monitors a hardwired input from the left (lighting) multi-function switch to determine the status of the turn signal switch, then controls turn signal operation and flash rate by energizing and de-energizing high side drivers, which control battery voltage outputs on the right or left turn signal feed circuits. The BCM also sends electronic turn signal switch status  messages to the IPC over the CAN data bus to control the illumination and flash rate of the left or right 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 turn signal flasher.