Classic/Antique Car Repair: no brake lights, turn signal switch, brake master cylinder

Question
can you tell me where the brake sensor or something of that nature would be on a 64 mustang. we have changed the bulbs the fuse. we are at a little bit of a stand still with this project. we would greatly appreciate any help you can give us.

thank you
jason

Answer
The brake lights switch is in one of two places.  

Most likely it is on the master cylinder. Look at the steel fluid lines that come out of the brake master cylinder and run along the chassis toward the front and rear wheels - right at the connection on the master cylinder will be a thing that looks like a mushroom screwed into the hydraulic lines that has a place for two wires on it.  That is the brake light switch.  

There should be 12 volts on one of the terminals, and when you are pushing on the brake pedal, there should also be 12 volts on the other terminal.  The ignition key may have to be on to test this.

If there is, and the brake lights are not coming on, there is probably a failure in your turn signal switch, which is up inside the steering column.  You can try wiggling your turn signal switch lever to see if this makes the brake light work on one side or the other.  If the problem is in the turn signal switch, it takes special tools to get apart, so you are going to have to take it to a shop with knowledge about this type of service.  But you can inspect the wires that go into the steering column to make sure that nothing is disconnected.  Also, of course, make sure the two wires on the switch are in good shape and making good contact.

If the switch is not on the hydraulic lines, it will be found on the pedal linkage under the dashboard - you will have to look under the dash for a switch which is pushed on by the brake pedal linkage.  The rest of the story is the same - in other words, the two wires mentioned above will be there.

Either type of switch should be available in stock at any NAPA store or other good parts store.

To detect whether you have 12 volts on the terminals, buy a test light from your local auto parts store - it will help you track down any kind of electrical problem in the car - it's a very valuable tool, and it's cheap!

Dick