Daytime Running Lamps (DRL)

The Body Control Module (PZM) will not activate the Daytime Running Lamps (DRL) feature if the headlamps have already been turned on through the headlamp switch or twilight sentinel.

Battery positive voltage (B+) is applied at all time to the switch side of the DRL relay via CKT 1640 (ORN). When the ignition switch is in the RUN position, the ambient light sensor indicates daytime conditions, and the gear selector is not in the PARK position, a message is sent from the instrument cluster to the PZM via the Class 2 serial data line to activate the DRL. With the ignition switch in the RUN position, battery positive voltage (B+) is applied to the coil side of DRL relay via CKT 439 (PNK). When the PZM receives a message from the instrument cluster to activate the DRL, the PZM provides a ground for the coil of DRL relay via CKT 592 (LT GRN/BLK). The coil is then energized closing the normally open switch contacts. Battery positive voltage (B+) is then applied through DRL Fuse cavity B9, the DRL relay, the daytime running lamps (DRL) resistor via CKT 589 (GRY), and DRL Fuse cavity D1 via CKT 12 (TAN/BLK) to the L HDLP LO Fuse and the R HDLP LO Fuse via CKT 12 (TAN), which feed the LH low beam headlamp and the RH low beam headlamp, respectively. Ground is provided to both headlamps from G101. The DRL resistor creates a voltage drop to the LH low beam headlamp and the RH low beam headlamp. This voltage drop causes the low beam headlamps to light at a reduced intensity.