Rear Fog Lamps

Rear fog lamps are installed on vehicles manufactured for all export markets. The rear fog lamp system includes the left (lighting) multi-function switch, the SCM, the EMIC and the TIPM. The rear fog 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 SCM monitors a hard wired multiplex input from the left multi-function switch to determine whether the rear fog lamps are selected, then sends electronic rear fog lamp switch status  messages to the EMIC over the LIN data bus. Then the EMIC relays an electronic rear fog lamp request  message to the TIPM over the CAN data bus. The TIPM responds to this message by providing a battery voltage output to the rear fog lamp bulbs through high side drivers on the fog lamp relay control rear circuit. The TIPM also sends the appropriate electronic message back to the EMIC to control the rear fog lamp indicator.

The TIPM will automatically energize and de-energize the front fog lamps in concert with the rear fog lamps. The TIPM 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 with the ignition switch in the LOCK position.