Twilight Sentinel

Twilight Sentinel performs two major functions. It determines automatic turn on/off control of the exterior lamps. It also holds the exterior lamps on for a period of time after the ignition switch is removed from the RUN position.

When the twilight sentinel is enabled, the instrument cluster twilight enable input is grounded via CKT 1784 (YEL/BLK) through the headlamp switch. When the ignition switch is in the RUN position, the ambient light sensor indicates darkness, and the twilight sentinel is enabled, the instrument cluster sends a request via the Class 2 serial data line to the body control module (PZM) to activate the low beam headlamps. The PZM then applies battery positive voltage (B+) to the coil of headlamp relay. The PZM also provides ground for the coil via CKT 10 (YEL). The low beam headlamps are then activated as previously described when activated with the headlamp switch. The park lamps are also turned on.

When the twilight sentinel is in the OFF position, the headlamp switch is in the OFF position, the ignition switch in the RUN position, the gear selector out of the PARK position, and the ambient light sensor indicates darkness, the instrument cluster will display a HEADLAMPS SUGGESTED message.

If the exterior lamps are on from an automatic turn on by the twilight sentinel, the twilight sentinel will keep the headlamps and park lamps on for a driver defined delay period when the ignition switch is removed from RUN. Activation of the headlamp switch will override all twilight sentinel operations.