USA/Canada Z49

CIRCUIT OPERATION
On vehicles equipped with daytime running lights (option T61), the Body Control Module (BCM) turns on the lo beam Headlamps at a reduced intensity whenever the Ignition Switch is in RUN and the transaxle is not in park. The daytime running lights feature will not activate if the Fog Lights or the Headlights already have been turned on.

The BCM controls DRL through a separate output terminal based on the status of the following inputs:
^ (Ignition 3 input) The Ignition Switch must be in the RUN position. When the Ignition Switch is in RUN, battery voltage is applied through Fuse A 13 and CKT 250 to terminal 3D6 of the BCM (the ignition 3 input).
^ (Park input) The park input must indicate that the transaxle is not in the park position. When the transaxle is in park, the Transaxle Range Switch is in the position shown on the schematic. When the Ignition Switch is in the RUN, BULB TEST or START position battery voltage is applied to terminal 3D8 (the park input) of the BCM through Fuse B9, CKT 439, the Transaxle Range Switch and CKT 275. Shifting the transaxle out of the park position opens the circuit at the Transaxle Range Switch and voltage is no longer applied to the park input of the BCM.
^ (Headlight status) The BCM will not activate DRL if the headlights already have been turned on through the Headlight Switch or Twilight Sentinel. Headlight Switch status is monitored at terminal 1D9 (the headlight switch input). The BCM monitors Twilight Sentinel status by checking the twilight photocell input and the Twilight Sentinel Switch state. The BCM monitors the Twilight Sentinel Switch state through the lighting data line.
^ (Fog light status) The BCM also will not activate DRL if the Fog Lights are on. Fog Light Switch status is monitored through the lighting data line by the BCM.

The BCM activates DRL by energizing the DRL Headlight Relay. Battery voltage is applied to the coil of the relay through Fuse B 11 and CKT 639 when the Ignition Switch is in RUN, BULB TEST or START. The BCM energizes the relay by grounding the coil through CKT 592 at terminal 2A11 (the DRL headlight relay output). When the relay energizes battery voltage is applied to the Daytime Running Lights Resistor and the lo beam Headlamps through Circuit Breaker 5, CKTs 661, 593 and 12. Some of the voltage is dropped across the Daytime Running Lights Resistor which reduces the brilliance of the Headlamps.

When the Headlamps are on through DRL the BCM will command the CCDIC message "HEADLAMPS SUGGESTED" (through the UART data line) when the Twilight Photocell indicates low ambient light.