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Brake Flasher

Here are the details of the project that gives me a flashing brake light with the rear brake and a steady brake light with the front brake. This is for a 1988 Concours. Other bikes may be a little different.

I went to AutoZone and got an electronic turn signal flasher, Tridon/Stant EP34 for about $10. It's a three wire unit that I connected downstream of the rear brake light switch. It's a direct replacement for a number of applications, but I don't know if the originals it replaces are the electronic type or not. It they are, fellow cheapskates may find it at a wrecking yard for less.

In its original configuration the unit flashed the brake light at the same speed as the turn signals. I wanted it faster than that, so I replaced the resistor that controls the speed. The capacitor is part of the team also, but I have more resistors to experiment with. It was just a matter of trying different values of resistance then soldering in a new one. Very simple. And cheap.


  • Tridon/Stant EP34 electronic flasher (or equivalent). Roughly $10
  • 33K ohm resistor, 1/4 watt. Radio Shack number 271-1341. 69 cents for five. A 47K resistor will make it flash at a slower rate and 22K will be faster.
  • Bullet crimp-on snap connectors. Radio Shack number 64-3085. $1.49 for a pack of 5 sets of 2. I used one female, two male. If you ground the flasher to the frame or another existing ground wire, use a suitable connector for that. You can also use squeeze-on splices to hook directly to the wires instead of the bullets.
  • Female crimp-on quick disconnect spade connectors. I used insulated, Radio Shack number 64-3058. $1.49 for a pack of 6.
  • Wire assemblies. Three pieces, approx 7", 18 gauge works great.
  • Fastening material. Anything handy. I used my trademark duct tape. A zip tie or double sided tape or wire tie is fine also. Or what the heck, just let it flop around on the fender.

Modification procedure:

Assemble three wires:
Two with a female spade and male bullet.
One wire with a spade and female bullet.
No extra charge for the greasy backdrop.

Remove the cover from the flasher. Slip a knife blade under the edge on one side and gently pry it upward, then do the other side. It'll pop right off.

Unsolder and remove the resistor in the upper right corner of the circuit board. The original is really small. 

Solder the new resistor in its place. The new one is larger, so I had to bend the leads and let it stand above the board.

I know, I know, the resistor in the picture is 39K, but disregard that.

Reinstall the cover. There is a little notch in the inside of the top so it will go on in only one direction.


Installation procedure:

Remove the bike's side cover and locate the blue wire from the rear brake light switch (top left in the picture).

Separate the bullet connection. You can check for the correct lead with a voltmeter or a test light.

The correct lead will have power only when the key is on and the rear brake pedal is pressed.

Attach the wire with a male bullet (shown as the red wire below) between the right side terminal on the flasher to the female bullet on the blue wire from the brake light switch. This is the power for the flasher.

Attach the wire with the female bullet (black wire below) between the center terminal on the flasher to the male bullet on the blue wire from the brake light switch. This is the output to the brake light bulbs.

Attach the remaining wire with a male bullet (black/red wire below) between the left side terminal on the flasher to the female bullet connector on the black wire in the set of hot power leads under the seat. This is ground for the flasher. Again, use a suitable connector if you use a different ground location.

Test by turning the ignition on and pressing the rear brake pedal. The brake light should flash. With it held down, squeeze the front brake lever. The brake light should stay on steady.
Secure the flasher unit as desired.


This flasher apparently needs to sense the current draw of two bulbs in parallel. The Connie has two bulbs and If my suspicions are correct, one burned out brake light bulb will make the flasher light the remaining one steady. This would be sort of a warning feature, a good thing. Of course, I won't know for sure until a bulb burns out.

I put dual filament bulb sockets in the rear turn signal housings and run 2357 bulbs there and in the front marker lights and tail lights. They have a higher output than the 1157.

I check the bulbs in the mirrors at a stop by pressing the rear brake and watching the reflection from objects behind, or while moving at night by observing the light on the ground behind.

I really hope this makes sense. For more info, drop me an email and I'll be happy to assist.

Article By: Cecil Warriner

April 2003

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