Fog/Driving Lamp: Description and Operation

FRONT FOG LAMPS
With the ignition switch in the ON or START position, the fog lamps will illuminate when the driver places the front fog lamp switch in the ON position. The dash integration module (DIM) controls the fog lamp relay coil. When the driver turns ON the front fog lamp switch, the switch momentarily grounds the front fog lamp input circuit of the DIM. In response to this input, the DIM grounds the control circuit of the fog lamp relay. The fuse block - underhood supplies battery positive voltage to the switch circuit of the front fog lamp relay. Ignition voltage is available to the fog lamp relay coil when the key is in the ON or START position. When the DIM grounds the control circuit the relay coil energizes, closing the switch contacts. Current then flows from the fog lamp relay switch to both front fog lamps. Both front fog lamps are permanently grounded at G104 The state of the front fog lamps will be retained when the ignition is cycled off and on.

The DIM will turn ON the park lamps when the fog lamps are ON and send a class 2 message to the instrument panel cluster (IPC) to enable the fog lamp indicator. The front fog lamps will deactivate when either the flash-to-pass or the high beam headlamps are turned ON. For vehicles exported to Japan or any European Country except Norway or Sweden the fog lamps remain illuminated with the operation of the high beam headlamps or flash-to-pass. The fog lamps are deactivated in Norway and Sweden when the low or high beam headlamps are turned ON.

REAR FOG LAMPS
Rear fog lamps are required equipment on some export vehicle equipped with RPO T79. The rear fog lamps are located in the rear deck lid lamp assembly. The rear fog lamps will only operate when the ignition in the RUN position and either the front fog lamps or headlamps are turned ON. When the driver turns ON the rear fog lamp switch, the switch momentarily grounds the rear fog lamp input circuit of the dash integration module (DIM). In response to this input, the DIM sends a class 2 message to the rear integration module (RIM). The RIM response to this message by grounding the rear fog lamp relay control circuit. The RIM also sends a class 2 message to the instrument panel module (IPM). The IPM will then illuminate the rear fog lamp indicator. When the rear fog lamp relay control circuit is grounded this energizes the rear fog lamp relay coil causing the switch side contacts to close. Supply voltage from the rear fog lamp fuse flows through the rear fog lamp relay switch to the rear fog lamps. The rear fog lamps have permanent ground at G402. The rear fog lamps will deactivate if the front fog lamps or headlamps are turned OFF, if the ignition is out of the RUN position, or if the driver turns the rear fog lamp switch OFF. The rear fog lamps will default to the OFF position upon a key cycle.