When the headlamp switch is placed in the ON position, the dash integration module (DIM) headlamp switch input is grounded.

The twilight delay switch in the headlamp switch is supplied a reference voltage from the instrument panel integration module (IPM). It is supplied a reference ground from the IPM. The switch is a potentiometer that resistance varies as the switch is moved. The IPM receives an input voltage proportional to the resistance of the potentiometer. The IPM sends a class 2 message to the dash integration module (DIM) indicating the on/off status and delay length for the twilight sentinel. With the twilight sentinel in an ON position, the DIM will automatically control the headlamps on/off status depending on the nighttime/daytime status of the ambient light sensor. The DIM will use the twilight sentinel delay length to know how long to keep the headlamps and park lamps on after the ignition switch transitions from ON to OFF during nighttime conditions.

The dash integration module (DIM) supplies battery positive voltage (B+) to the HDLP LO BM relay coil when the headlamps or park lamps need to be on or when the ignition switch is in the ON position. Battery positive voltage (B+) is always supplied to the HDLP LO BM relay coil through the underhood fuse block. When the headlamps are to be active, the DIM supplies ground to the low/high beam switch in the headlamp dimmer switch. With the headlamp dimmer switch in the low beam position, the HDLP LO BM relay coil is grounded. The coil is energized, closing the switch contacts. This supplies battery positive voltage (B+) to the HDLOBML Fuse and HDLOBMR Fuse. HDLOBML Fuse supplies battery positive voltage (B+) to the LH low beam headlamp. HDLOBMR Fuse supplies battery positive voltage (B+) to the RH low beam headlamp. The LH and RH low beam headlamps are both permanently grounded so both low beam headlamps have power and ground, and then light.

The dash integration module (DIM) supplies battery positive voltage (B+) to the HDLP HI BM relay coil when the headlamps or park lamps need to be on or when the ignition switch is in ON position. Battery positive voltage (B+) is always supplied to the HDLP HI BM relay coil through the underhood fuse block. When the low beam headlamps are on as described above and then the headlamp dimmer switch is placed in the high beam position, the HDLP HI BM relay coil is grounded. The coil is energized, closing the switch contacts. This supplies battery positive voltage (B+) to the HDHIBML Fuse and HDHIBMR Fuse. HDHIBML Fuse supplies battery positive voltage (B+) to the LH high beam headlamp. HDHIBMR Fuse supplies battery positive voltage (B+) to the RH high beam headlamp. The RH high beam headlamp is permanently grounded. The LH high beam headlamp is grounded via the DRL Relay when not energized, Both high beam headlamps have power and ground, and then light.

The flash-to-pass switch is permanently grounded. When the headlamp dimmer switch is pulled slightly toward the driver, the flash-to-pass switch in the headlamp dimmer switch closes. The DIM Flash-To-Pass input is grounded. In response to this input, the DIM supplies ground to the HDLP HI BM relay coil. The HDLP HI BM relay has battery positive voltage (B+) as described above. The relay is energized closing the switch contacts. The high beam headlamps are supplied battery positive voltage (B+) as described above. If the low beam headlamps are already on, they will remain on during flash-to-pass. The high beam headlamps will only remain on as long as the switch is held.

The ambient light sensor is supplied a reference ground from the instrument panel integration module (IPM). The sensor is a light sensitive variable current source that varies as the outside ambient light level changes. The IPM receives an input voltage proportional to the current of the sensor. The IPM sends a Class 2 message to the dash integration module (DIM) and the rear integration module (RIM) indicating the daytime/nighttime status. The DIM uses the daytime/nighttime status of the ambient light sensor in order to automatically turn on and off the headlamps with the twilight sentinel on. The RIM uses the daytime/nighttime status of the ambient light sensor in order to turn on and off the automatic interior courtesy lamps function with the interior lamp switch in the AUTO (off) position.

With the daytime running lamps (DRL) programmed to be on, the DRL will operate when the ignition switch is in the ON position, the gear selector lever is out of the PARK position, the headlamp switch is in the OFF or PARK position, and the ambient light sensor indicates daytime conditions. Battery positive voltage (B+) is supplied to the DRL relay coil through the underhood fuse block. Battery positive voltage is supplied through the underhood fuse block FOG/DRL Fuse to the DRL relay normally open contact. The DRL relay normally closed contact receives ground for normal high headlamp operation. When the dash integration module (DIM) determines that conditions are right for the DRL, the DIM grounds the DRL relay coil. This energizes the DRL relay coil and closes the switch to the normally open contact. Battery positive voltage (B+) is supplied to the LH and RH high beam headlamps in series. The high beam headlamps split the voltage and each lights at half intensity. Current will follow the path from the DRL relay to the LH high beam headlamp, HDHIBML Fuse, HDHIBMR Fuse, the RH high beam headlamp, then to ground.

When the remote function actuator (RFA) module receives a door unlock command from the remote function actuator transmitter, the RFA will send a class 2 message to the dash integration module (DIM) indicating that a remote function actuator unlock command was received. In response to the message and if the twilight sensor indicates nighttime conditions, the DIM will activate the headlamp and park lamp relay. The DIM will flash the headlights and park lights twice, then they will remain on for approximatly 25 seconds or until a door is opened. When the remote function actuator (RFA) module receives a door lock command from the remote function actuator transmitter, the DIM will flash the headlights and park lights once.