How to adjust a turn signal flasher
By Bruce (gt390xr7)

Need a flasher for your 69/70 cougar and can't find the correct "sequential" one? This "how to" will explain how to modify a standard flasher for use with our unique directionals.

A flasher is nothing more than an automated relay. It uses a set of contact points to open and close the circuit much like the old point type distributors. Flashers are thermal, though, not mechanical. You can change the amount of time between cycles by "adjusting the points". Here's how:

  • Remove the cover of the flasher(preferably so you can put it back on) to expose the inside.
  • Flasher Guts
    (Photo from

  • Plug the flasher (without the cover) back in and turn the key to the "Acc" position.

  • Turn on the directional (direction dosen't matter).

  • With the blinkers flashing, move the the stationary point closer or further away from the bimetal point to get the flash speed you want.

  • When you have the flash speed you want, start the engine and confirm the speed is still good. You do this to test the speed with increased voltage from the alternator.

  • If you are happy with the circuit timing, shut off the engine and securely reattach the flasher cover.

  • Confirm flash speed once more after putting everything back together.

  • If you are satisfied, take a ride and enjoy......

    To see how a thermal flasher works, click HERE.