1965 brake lights only work if headlights on

[Rocketdoc]

My brake lights only work if parking or brake lights are on. The relay clicks in all cases if pedal depressed?! Bad relay?

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[74 Harley]

Check your grounds.

 

[Rocketdoc]

Check your grounds.

If poor grounding why do they only work if lights are on?

 

[Ward 57]

If the relay clicks you know it's working. Grounds are important. Do the turn signals work when the lights are off? Those are the same filaments for the brakes. if they do I'd trace back the wiring to the source. A bad connection at the power source? The circuits are more complicated than my '57 so it could be at the ignition switch. The brake lights should work whether the ignition or lights are on. That is where you need to look. Are there two positive wires to the brake light switch or only one and trace it back from there.

 

[Rocketdoc]

Lights flashers directionals all work as they should with out the lights on but - brake lights only work if the parking or headlights are on. The brake light relay clicks as it should also!

 

[Ward 57]

Lights flashers directionals all work as they should with out the lights on but - brake lights only work if the parking or headlights are on. The brake light relay clicks as it should also!

There has got to be another source of power you are missing. keep digging.