Operate the pedal and gear selector, then investigate the circuit when a lamp behaves unexpectedly.
Brake lights respond to pedal input; reverse lamps respond to reverse-range input. These are independent commands in this teaching model.
Faults and wiring are simplified. Modern vehicles may use a body control module, LED drivers and monitored circuits.
Approximate loaded DC voltages; an open-circuit terminal may float. These values are for diagnostic practice, not a vehicle wiring specification.
With the brake pedal pressed, both brake lamps remain dark. The brake fuse output reads 12.6 V, but the brake switch output reads 0 V. What should you inspect?