How can I diagnose the problem
The brake lights won't come on when I brake. I replaced the brake switch. on 1994 Toyota Celica
You can diagnose it by having a wiring diagram of the circuit , and an understanding of how it works , and by then using that information along with a volt-ohmmeter to test for power , ground and continuity as needed.Or check the wire harness in trunk along the hinge for a broken wire.
was it a broken wire in the trunk harness?
Don't know yet did not have time to test. I will post results soon.