Review the Headlamps Electrical Schematic (Preliminary Checks)

Review the schematic, it is essential to understand how a circuit should work before trying to figure out why it doesn't. After understanding how a circuit should operate, read the schematic again, this time keeping in mind what has been learned by operating the circuit. Since both the low beam headlamps are inoperative, ensure that the following components are operating properly.
^ The headlamp Switch.
^ The YEL wire.
^ Low contacts of the Headlamp Dimmer Switch.
^ C100 terminal 1E.
^ The TAN wires. Grounds G105 and G109.