Rear Tail Lamps
| Refer to COMPONENT INDEX . |
- Backup Lamp
On vehicles with an automatic transmission the BCM monitors a CAN-C signal which indicates the state of the PRNDL display. When the display signal indicates R everse, the BCM activates the left and right reverse lamps and then outputs a signal that states that the reverse gear is active for as long as the signal remains true.
If the vehicle is equipped with a manual transmission, the BCM monitors the manual transmission reverse switch. When the reverse switch is active, the BCM activates the left and right reverse lamps for as long as the switch state is active. The BCM also outputs the reverse gear active signal on the CAN bus for the duration of the event.
Note that on certain models there are optional auxiliary reverse spot lamps that are exterior mirror mounted. These operate in the same manner with the same commands as the tail lamp equipped reverse lamps. There is one spot lamp located in the left and right mirrors. These spot lamps have a very bright output that illuminate on the side of the vehicle in order to aid in backing up the vehicle in dimly lit or night time conditions. The auxiliary reverse spot lamps are only serviced with a complete mirror assembly.
- Brake Lamp
If the vehicle is equipped with combined rear lighting, then the same bulb filament/LED array is used for both the stop and turn signal functions. When the stop lamps are active and a turn signal is activated, one of the stop lamps will become a turn signal display and will return to a stop display when the turn signal event has completed.
The BCM has a hardwired connection to the ABS module. This path is used to accommodate redundancy and ensure that the brake lamps will be functional in the event of a CAN bus issues between these two modules. This connection is known as the "redundancy to tail light" signal.
The BCM receives the brake pedal sensor input from the ABS module over the CAN-C bus as well as through and a hardwired redundancy signal indicating that the brake pedal is pressed or that the ABS module is honoring an autonomous braking event. The ABS module sets the high side hardwired binary redundancy signal to the BCM to TRUE when braking is occurring except during trailer brake suppression events. When trailer brake suppression is occurring, the ABS module still sends the braking signal over the CAN bus but, as mentioned, the hardwired redundancy signal is not activated and will not indicate that the brakes are being applied.
When the BCM receives the brake lamp request over the CAN bus and/or through the hardwired redundancy signal, it will switch on all the stop lamps and the CHMSL.
If the vehicle is equipped with the police rear wig-wag system, THE BCM activates the wig-wag by alternating the right and left turn signal outputs until the signal is no longer active from the VSIM.
- Turn Signal Lamp
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.