69 Headlight switch issues

[lieser26 0]

I hope someone can help

overview:
when headlights are off, brake lights and turn signals work fine BUT when headlights are on, I get no taillights and no brake lights but turn signals work

parking lights don't work either

dash lights will flicker and I hear a noise when they do (it sounds similar to a metal spring being flicked is the best way I could describe it)

I've replaced the headlight switch twice so im thinking it has to be another issue? please help its been a pain in the ass

[Midlife 814]

Running lights don't go through the turn signal switch, but brake lights and turn signals do (mixed at the turn signal switch).  Parking lights will work only at the first detent of the switch.  Dash lights go through the fuse box, so I would double-check you have voltage on both sides of the smallest fuse.

Sounds to me like a combination of problems, but the turn signal switch is always suspect given most of your symptoms.

[Mach1 Driver 560]

Just to be clear, do you have OEM harnesses and 1157 incandescent bulbs?

The 1157 bulbs have two filaments that connect to a common ground. If the ground gets flaky, power will go through one filament then out the other filament and find a ground through the side markers and license plate light. It won't be as bright as it should be, but it will light...until you turn on the headlights and eliminate that path. This is a schematic, not a wire diagram. A schematic simplifies the circuit so it is easier to see how it works. You can find a copy of the entire schematic and a wire diagram in "How tos".

I think you have poor tail light grounds. The yellow shows the current path for the stop lights if the grounds are bad. The same thing happens with directional signals. When you turn on the light switch, the path to ground goes away because of positive power to the side marker and license lights.