[T3] DOT 5 and brake light switches

[Sean Bartnik]

> The problem with air bubbles is that they are compressible, so it 
> takes more stroke of the pedal to develop a given pressure in a 
> system that has bubbles in it. If the total volume of bubbles is 
> large enough, the pedal will go all the way to the floor before 
> significant pressure is raised. In your case, the brakes worked, so 
> you know the pressure was sufficient.
> 

Yes I have good hard pedal with no signs of bleed-down.

> In case there's any question, here's how to test the dual brake 
> switches in a tandem system:
> 

My troubleshooting process is much simpler because, while I have a dual-circuit master cylinder, I still have single-circuit electrics for the brake lights.  So while there are two switches installed on my master cylinder, only one of them is electrically connected.  Pull wires from switch, connect together, turn on ignition.  Brake lights turn on.  Connect wires to switch, ignition on, press brake pedal = no lights.

Worth noting that the FTE switch makes a loud click when it switches on.  It can actually be heard inside the car even with the engine at idle, as long as the turn signals aren’t on (their clicking covers up the brake switch click).

When the switch failed, the lights did not come on (of course) and there was also no click from the switch - switch was not being activated by the hydraulic pressure for whatever reason.  I don’t know if that tells you anything but that’s what was going on.

New switch is still clickin’.  When I stop hearing the click then I know it’s time to see if the lights are still working.

-Sean