Exterior Lighting
EXTERIOR LIGHTINGThe BCM controls the Exterior Lights via the appropriate relays, based on input from the Exterior Light Mode Switch. The BCM reads the position of the Exterior Light Mode Switch, and turns on the corresponding Exterior Lamps. The Exterior Lights are:
- Park Lamps
- Low Beams
- High Beams
- Front Fogs (optional)
- Rear Fogs (export markets)
If the Exterior Lamp Mode Switch is in the Lowbeam position, and then the ignition is turned off, followed by the customer turning off the Exterior Lamp Mode Switch, the BCM enters the Headlamp Delay mode. In this mode, the Lowbeam Lamps are left on for either 30, 60, or 90 seconds. The time period can be changed via the DRB III (R). This mode is exited if the ignition switch or the Exterior Lamp Mode Switch is cycled.
In certain conditions, the BCM will also control certain Exterior Lamps to signal special conditions (VTSS alarm, etc).
In the Canadian market, the BCM enables the Daylight Running Lamp (DRL) mode. The High-beam Relay is replaced in the JB with a solid-state relay. The BCM will duty cycle this relay when the engine is running and the Lowbeam Lamps are not on.
If either the Exterior Lamps are left on with the ignition in the OFF position for greater than 8 minutes, the BCM will turn off ("Loadshed") the lamps until another cycle occurs (i.e. ignition is turned on, Exterior Lamp Mode Switch position is changed, etc.). This feature exists to attempt to save the vehicle battery in the event that a customer forgets to turn off the headlamps, etc. On export vehicles, the park lamps do not "Loadshed".
Refer to Body Control System.
Body Control Module
Refer to The Programmable Communication Interface Multiplex System (PCI Bus).
Information Bus