Front Headlamps
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The headlamp system includes the IPC, BCM, Headlamp switch and the SCCM on the steering column. The headlamp bulbs have a path to ground at all times through their connection to the engine compartment wire harness. The engine compartment harness has takeouts with eyelet terminals that are secured by nuts to ground studs on the front end sheet metal within the engine compartment. The BCM monitors headlamp switch inputs to determine whether the headlamp high or low beams are selected. The BCM then controls headlamp illumination through relays soldered onto the BCM internal circuit board. When the BCM detects a change in headlamp beam selection, the BCM energizes or de-energizes a high side driver, which controls an output to the solenoid that operates the shutter in each headlamp. The BCM also sends the appropriate electronic messages to the IPC to control the illumination of the high beam indicator. The BCM remembers which beams (LOW or HIGH) were selected when the headlamps were last turned OFF, and energizes those beams again the next time the headlamps are turned ON. Each headlamp includes an integral reflector adjustment screw to be used for static aiming of the headlamps. The BCM will store a Diagnostic Trouble Code (DTC) for any shorts or opens in the headlamp circuits.
- Park Lamps - The park lamps system includes the left (lighting) multifunction switch, the SCCM, the IPC and the BCM. The front park/turn lamp and the position lamp bulbs each have a path to ground at all times through their connection to the engine compartment wire harness. The engine compartment wire harness has takeouts with eyelet terminals that are secured by nuts to ground studs on the front end sheet metal within the engine compartment. The rear lamp units and license plate 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 nut to a ground stud on the body sheet metal within the passenger compartment.
The IPC relays the appropriate electronic message to the BCM over the CAN data bus. The BCM responds to these messages by providing a battery voltage output to the appropriate lamp bulbs through high side drivers on the proper park/tail/license/running lamp right and left circuits. The BCM and the SCCM also send the appropriate electronic messages to the IPC to control the illumination and lighting level of the panel lamps.
The BCM provides a battery saver (load shedding) feature for the park lamps, which will turn these lamps OFF if they are left ON for more than about eight minutes with the ignition switch in the LOCK position. The SCCM and the IPC each provide a fail-safe feature for the park lamps, which will send an electronic message to the BCM to turn these lamps ON automatically if there is no input available from the left multifunction switch. The BCM also provides a fail-safe feature for the park lamps that will turn these lamps ON automatically whenever a loss of CAN bus communication is detected with the ignition switch in the ON position.
- Turn Signal Lamps - The turn signal lamps system includes the left (lighting) multifunction switch, 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 engine compartment wire harness. The engine compartment wire harness has a takeout with an eyelet terminal that is secured by a nut to a ground stud on the body sheet metal within the engine compartment. 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 nut to a ground stud on the body sheet metal within the passenger compartment.
The SCCM monitors a hard wired multiplex input from the left multifunction switch to determine the status of the turn signal switch, then sends the appropriate electronic turn signal switch status messages to the IPC over the LIN data bus. Then the IPC relays an electronic turn signal request message 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 right or left turn signal feed circuits. The BCM also sends the appropriate electronic messages back 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 turn signal flasher.
The IPC also provides a turn signal ON warning that will generate repetitive chimes to indicate that a turn signal has been active continuously for 1.6 kilometers (1 mile) with the vehicle speed greater than 22 km/h (15 mph). Vehicles built for markets other than the United States and Canada have a revised distance threshold of 4 kilometers (2.49 miles) for this feature. 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.
- Side Marker Lamps - The side marker lamps are activated when the front or rear park lamps are activated except where prohibited.
- Police Front Wig-Wag - The police front wig-wag feature will function when the ignition is in the ACC, RUN or START position. When the BCM receives a CAN-C bus message from the VSIM that the wig-wag lamps are requested, the BCM activates the front wig-wag by alternating the left and right high beam headlamp outputs. When the switch is turned off in the VSIM, the VSIM will send a CAN-C message to the BCM requesting termination of the front wig-wag lamps. The BCM responds by deactivated the front wig-wags.