Part 3

When conditions for DRL operation exist, the powertrain control module (PCM) sends a message via GMLAN serial data to the instrument panel module (IPM) indicating the transmission has been removed from the PARK position. The ambient light sensor is a light sensitive transistor that varies its voltage signal to the HVAC control module in response to changes to the outside (ambient) light level. When the HVAC control module receives this signal it communicates via GMLAN with the IPM. The IPM either turns ON the DRLs using a reduced output or the low beam headlamps at full intensity for auto headlamp operation. Any function or condition that turns the headlamps ON will cancel the DRLs operation. The DRLs consists of the low beam headlamps. With the headlamp switch in the OFF position, the headlamps will either be turned ON or OFF, after an approximate 8 second delay depending on whether daylight or low light conditions are sensed.

Twilight Sentinel

Twilight sentinel is a driver convenience that controls the exterior lamps in response to changes to the outside, ambient light level. The twilight sentinel will also keep the low beam headlamps and park lamps ON for a pre-selected period of time after the ignition is turned to the OFF position when night time conditions are sensed. The twilight delay is programmable through the driver information center (DIC) for Driver 1 and Driver 2.

* 0 seconds
* 15 seconds
* 30 seconds
* 60 seconds
* 90 seconds
* 120 seconds
* 180 seconds
* 240 seconds

The DIC will enable the park/headlamp delay feature under the following conditions:

* The time delay is programed to 15 seconds or more for the current driver.
* The headlamp switch is in the auto position.
* The automatic headlamp feature has not been canceled.
* The ambient light sensor status is night time.
* The ignition is OFF.

The delay timer starts once the ignition is turned OFF. The lights will not turn OFF until the set time has been completed or the keyless entry system receives a request for door unlock or trunk release.

Front Fog Lamps

With the ignition switch in the ON or START position, the front fog lamps will illuminate when the driver toggles the front fog lamp switch to the ON position. The front fog lamp switch is a momentary switch that requires the driver to briefly place the front fog lamp switch to the ON position and release it. The instrument panel module (IPM) controls the front fog lamp relay coil. When the driver toggles the front fog lamp switch to the ON position, the switch supplies ground to the front fog lamp switch signal circuit of the IPM. In response to this input, the IPM supplies ground to the front fog lamp relay control circuit. The underhood fuse block supplies battery positive voltage to the switch circuit of the front fog lamp relay. Ignition voltage is available to the front fog lamp relay coil when the key is in the RUN or CRANK positions. When the IPM grounds the front fog lamp relay control circuit the relay coil energizes, closing the switch contacts. Current then flows from the fog lamp fuse through the front fog lamp relay switch to both front fog lamps. Both front fog lamps are permanently grounded. The front fog lamps will default to the OFF position upon a key cycle.

The IPM will turn the park lamps ON when the front fog lamps are ON and send a message via GMLAN serial data to the instrument panel cluster (IPC) to enable the front 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 front fog lamps will remain illuminated with the operation of the high beam headlamps or flash-to-pass.

Rear Fog Lamps - European

Rear fog lamps are required equipment on some export vehicles. 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 or CRANK positions and either the front fog lamps or headlamps are turned ON. When the driver turns the rear fog lamp switch ON, the switch supplies ground to the rear fog lamp switch signal circuit of the instrument panel module (IPM). In response to this input, the IPM sends a message via GMLAN serial data to the rear integration module (RIM). The RIM responds to this message by grounding the rear fog lamp relay control circuit. 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 IPM communicates via GMLAN serial data with the instrument panel cluster (IPC) requesting the rear fog lamp indicator be illuminated. The rear fog lamps will deactivate if the front fog lamps or headlamps are turned OFF, if the ignition is out of the RUN or CRANK 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.

Park, Tail, License, and Marker Lamps

The tail, stop, and turn signal functions are performed by the quarter mounted tail lamps. The quarter mounted tail lamps consist of red lenses and light emitting diodes (LED) instead of incandescent bulbs. The tail lamp assemblies wrap around the corners of the vehicle and serve as the rear side marker. The lower portion of each lamp contains reflectors to alert approaching vehicles for night time driving safety. The park, tail, license, and marker lamps are turned ON when the headlamp switch is placed in the park lamp or headlamp position or anytime the headlights are requested. The park lamps are also turned ON with the front fog lamps. When the ignition switch is in the ON position, the instrument panel module (IPM) provides ground to the controlled voltage circuit of the park lamp relay coil. The underhood fuse block supplies battery positive voltage to the switch contacts of the park lamp relay. When the headlamp switch is placed in the park lamp or headlamp positions, the park lamp switch ON signal circuit is provided ground. In response to this signal, the IPM provides ground to the control circuit of the park lamp relay coil, which energizes the relay coil. When the park lamp relay coil is energized, the relay switch contacts close causing current to flow from the park lamp relay to the LIC/Dimming fuse, LT PARK fuse, and to the RT PARK fuse. From these fuses, current flows to the park lamps, license lamps, side marker lamps, and tail lamps. The LIC/dimming fuse supplies battery positive voltage to the license lamps and IPM instrument panel lamp fuse supply voltage circuit for interior lamps dimming. The inadvertent power control feature prevents the park lamps from remaining on more than 10 minutes if left ON. If the park lamps are turned ON after the ignition switch has been turned OFF, or is in the ACCY position, they will remain ON until turned OFF or the battery runs dead.