Exterior Lighting Control: Notes

The headlamps and park lamps are controlled by external relays which are controlled by the body control module. The headlamp relays are located in the power distribution center and the parklamp relay is located in the micro relay center behind the glove box. When the park lamp switch is turned ON (signals as a ground) the BCM then grounds the park lamp relay to provide power to the park, tail and marker lamps. The park lamp power feed, which is controlled by the BCM, also provides back-up power to the BCM. In the event that the ignition is turned off with the park lamps still on, the BCM will function normally (as if the IOD had been reconnected) until the park lamps are turned off. When the headlamp switch is turned on, (signals as a B+ feed) the BCM grounds low beam and high beam headlamp relay coils to turn on the headlamps. However, the high beams will not turn on until the dimmer switch is activated.