Brake Lights don't work

[BillyBob]

A few years ago my brake light switch was changed from hydraulic to mechanical. The brake lights worked for "some time".  Now, not working. The mechanical switch was connected to the pressure light wires that head back to brake lights. Current diagnosis is that turn switch is defective as it feeds power to brake lights. Does that make sense? Fuse is good, both bulb filaments are functional (have park lights and turn signal on both sides), and mechanical switch checks ok.  What to do? Thanks, BillyBob

[Gunslinger]

Did you or anyone use a test light to make sure the power lead from the turn signal switch is actually working?  How was the mechanical switch wired into the hydraulic switch?  If it's wired into the hydraulic switch circuit in the lead that would go to the rear of the car, the hydraulic switch could be bad and not sending a signal to the mechanical switch.  

I would use a test light to make sure the mechanical switch is getting power when the brake pedal is depressed.  If it is but no signal going out of the mechanical switch then you have either a bad mechanical switch or a bad ground.  Electrical grounds are critical in a fiberglass car and the cause of many problems.  

If you have a tester that can send an electrical signal (not expensive), then you can test the mechanical switch to either confirm or eliminate it.  If the mechanical switch tests good, then start going backward through the circuit.  Start with the easy and work from there...don't start condemning things until you do basic tests.