High Beam Operation and Flash-to-Pass

High beam operation is enabled by pulling the multifunction lever (turn signal stalk) towards the driver. If the low beams are already on, the headlamp system will change state to high beams. If the low beams are not on and the ignition switch is in the RUN position, the high beams will turn on for as long as the multifunction lever is pulled and held inward (flash-to-pass).

When the multi-function lever is pulled inward, the headlamp dimmer switch closes, supplying battery positive voltage (B+) to the instrument cluster high beams/flash-to-pass input. In response to this input, the instrument cluster sends a request via the Class 2 serial data line to the PZM to activate the high beam headlamps. The PZM provides a ground for the coil of the high/low beam headlamp relay via CKT 1969 (BLK/WHT). The coil is then energized causing the switch contacts to close and apply battery positive voltage (B+) via CKT 11 (LT GRN) through the L HDLP HI Fuse and R HDLP HI Fuse to the LH and RH high beam headlamps, respectively. For Eldorado, the RH high beam headlamp is grounded to G101 and the LH high beam headlamp receives ground through DRL relay from G101.For DeVille, the LH and RH high beam headlamps are both grounded to G101. When the switch contacts of high/low beam headlamp relay close, battery positive voltage (B+) is removed from the low beam headlamps causing them to turn off when the high beam headlamps are on.