Verify that the battery voltage is normal.
If the battery voltage is not normal, charge or replace the battery.
Verify that the fuses are normal.
If an abnormal condition such as a blowout is found in a fuse, inspect or repair the cause of the abnormal condition before replacing the fuse.
Confirm that the ground point is normal.
Repair and clean the ground point if improperly installed or significantly dirty.
Verify that the harness connectors are normal.
Inspect for poor connections at the connectors, worn or bent harnesses, or split wires inside the harness shorted to other circuits.
Check for any interference from aftermarket electronic components such as two-way radios or lights.
Remove any aftermarket electronic components or turn OFF the power to ensure that there is no influence on inspections or operations.
Check the following headlight circuits for an open circuit, short to the power supply, short to ground, and high resistance.
If a malfunction is found in the circuit, repair or replace the applicable circuit.
If the components and circuits are normal, replace the BCM.