Headlamp: Description and Operation
CIRCUIT OPERATIONWhen the headlamp switch is in the ON position, the A3 circuit from the Power Distribution Center (PDC) connects to circuit L4 (for LOW beam operation). The L4 circuit is spliced and connects a BUS bar in the junction block and to the Body Control Module (BCM). Circuits L43 and L44 connect to the BUS bar in the junction block, and power the low-beam headlamps. Circuit L43 supplies power to the left headlamp. Circuit L44 supplies power to the right headlamp. The L43 and L44 circuits each have separate fuses in the junction block. The L43 circuit is protected by a 10 Amp fuse in cavity 12, and L44 is protected by a 20 Amp fuse in cavity 13.
When the operator selects high-beam operation, with the turn signal stalk of the multi-function switch, circuit A3 connects to the L3 circuit. Circuit L3 powers high-beam operation. This circuit is spliced and provides an input to the BCM, along with supplying power to the high-beam fuses in the junction block.
Circuit L33 is used for left high-beam operation and is protected by a 10 Amp fuse located in cavity 3 of the junction block. Circuit L34 is used for the right high-beam and is protected by a 10 Amp fuse located in cavity 2 of the junction block.
Headlamp Ground
Although circuit Z1 provides ground for the right and left headlamps, it has different termination points. For the right headlamp, the Z1 circuit is terminated at the right frame rail. For the left headlamp, the Z1 terminates at the left strut tower.