wiring auto directionals

Thread Starter


Joined May 11, 2005
I am attempting to make a directional system for a project vehicle. i have 2 rear taillightes, each lite has one 1157 dual elementbulb, i have a brakelight switch and a directional switch and a 2 or 3 prong flasher. i have done a rough install to see of it all works. I can get the low side of each bulb to light ican get the high side to blink on either or the brake lights to both come on but my problem is if i put on the left or right directional on and step on the brakes it stops blinking how do i wire this so when i step on the brakes one side stays bright and the other side remains blinking.


Joined Mar 5, 2005
The bulbs have two buttons of solder, one for the brake and one for the signal, the return wire is the metal case or chassis ground.

(o) <--- connection (O) <--- Bulb (----/ o---) <----switch

Sounds like you need to wire the high filaments in parallel for the brake.
You can take the wire from the brake switch and make a split connection one going to the same connection terminal on each bulb holder.

right bulb-->----------------------------------O then to Chassis ground
Brake Switch-----/ .__hot wire________|
left bulb--> ----------------------------------O then to Chassis ground

for the Signal switch you need two wires for this,

Right turn switch_________/ o______O____>to Chassis ground

Left turn switch_________/ o_______O____>to Chassis ground

The chassis ground is usually the metal shell in both bulbs. in the newer cars there is a separate wire for ground but it is hooked to the shell.
both filaments are connected to the shell ground .

shell---> ( turn button> o o <----brake button)

David Bridgen

Joined Feb 10, 2005
It isn't clear, rvjw, exactly what you want to happen.

Which of the two filaments in each bulb, the higher power one or the lower, do you want lit when you apply the brakes, or is it both?

What should happen when you give a direction indication, 1) without brakes applied and 2) with brakes applied?

(I tried using "a" and "b" instead of the numerals 1 and 2, but both upper or lower-case b followed by a bracket produce a damned silly smiley instead.)

Thread Starter


Joined May 11, 2005
I am attempting to wire a custom motorcycle that has 2 red lights in the rear and 2 running lights in front
what I want to happen is the same as a car when you apply the brakes both bright elements in the rear bulbs come on while the brakes are applied and you put on the turn signal one rear light stays constent while the other flashes.
dont forget that the front lights need to blink but not come on when the brake lights do