Rear Fog Lamps

Rear fog lamps are installed on vehicles manufactured for all export markets. The rear fog lamp system includes the headlamp switch, the EMIC and the BCM. The rear fog lamps have a path to ground at all times through their connection to the rear fascia wire harness.

The EMIC monitors a hardwired multiplex input from the headlamp switch to determine whether the rear fog lamps are selected, then sends electronic rear fog lamp switch status  messages to the BCM over the CAN data bus. The BCM responds to this message by providing a voltage output to the rear fog lamps. The BCM also sends the appropriate electronic messages to the EMIC to illuminate or extinguish the rear fog lamp indicator.

The BCM will automatically de-energize the rear fog lamps any time the front fog lamps are deselected or when the automatic headlamps feature turns the headlamps OFF. However, the rear fog lamps must always be turned ON manually, even after they've been turned OFF automatically. The BCM also provides a battery saver (load shedding) feature for the rear fog lamps, which will turn these lamps OFF if they are left ON for more than about eight minutes after the electronic ignition switch status  messages from the WIN indicate the ignition LOCK position is selected.