Updating the brake light switch

The three-prong brake light switches in the later cars have had a rather high failure rate.  We are replacing them as they are needed.  If yours requires excessive pressure to actuate the lights, e-mail me for an update package.  You can also do it yourself  aquiring a Cole Hersee switch 8626 (Equivalents: Ford 100810B, GM 403936, Wagner FC5106) and installing it by following the instructions below.

*After the new switch is installed, the brake warning light on the dash (if you had one) will no longer work.

If you have a switch in each master cylinder, you only need to replace one switch.  Do not remove the second switch!

New switch

Parts included:

  • Brake switch
  • ¼” electrical (male) tabs
  • Shrink tubing
  • Female push-on connnectors


  • Remove the brake master cylinder cover.
  • Remove the electrical plugs at the rear end of the cylinders.
Brake box
  • Have the new switch ready to install, complete with a small amount of low-strength sealant like blue Locktite on the threads. 
  • Remove the outside switch with a socket or box wrench.  Quickly replace it with the new switch – but leave it loose.
  • Let fluid seep from the connection for the time necessary for 20 or so drops to leak.  If you have a helper, have them push on the pedal lightly.
  • Tighten the new switch to 12 lbft.
  • Dry the threads around the switch.  Let the car sit for at least one hour before you apply brake pressure.
  • If you have two brake switch sockets, cut the three wires as shown at the right.
  • Tape the violet wire completely where it comes out of the harness.  It's no longer needed.
  • Trim the “stubs” of the other two wires close to where they join together.
Sockets for dual switches

  • Use a small jeweler’s screwdriver to remove the green and pink wire terminals from the remaining socket.  Push the flat blade into the small slot adjacent to the blade.  It will flatten a retaining tab so that the terminal can be removed.  Alternately, if you have a good crimper, you can cut the wires and put on a new terminal end.
Removing the connector
  • Cover the bare terminals with the included shrink tubing and shrink with a heat gun or match.
  • Attach the male tabs to the switch posts with the screws included.
  • Connect the wires as shown (although they can be reversed without a problem).
  • Press hard on the brake pedal and check for leaks at the threads.
  • Replace the brake cover.