Tail light/brake light

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Roadart

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72 dart,with tail light on apply brake pedal brake light comes on tail light goes out. Changed bulb same scenario. Ideas??? Opposite side works fine.
 
The older Chevs around 60-66 were "world famous" because some of the lamps were in the trunk lid and those ALWAYS had ground issues. This amounted to quite a "Christmas tree" display what with application of turn/ brake/ tail at various times LOLOL
 
Without brake applied. Is the brightness on the left side same as on the right side?

With brake applied. Is the brightness on the left side same as on the right side?
 
Without brake applied both sides are the same brightness. With brake applied left side tail light goes out,brake light stays on.Right side is not affected either way. Further problems. I have power to the bulb base in the socket but the bulb does not light up. I replaced the ground on the left side no difference. If you suggest ground,where to place it at the light source.
 
I'd use a jumper wire and attach one end to the metal part of the bulb housing, and the other end to a good ground on the bumper. Then see if that cures the problem. If so, you need a better ground to that taillight housing.
 
Will try that again(did it earlier with no success).Will try different spot. I even took bumper off to see things better. It is now sitting outside where it belongs with original wiring all connected.
 
With the bumper off, you will definitely need to run some good ground wires to do proper testing.
 
Just put jumper wire on two different spots,no tail light.(attached to bumper than metal around light frame and tried touching light socket outside)
 
I'm not sold on a ground issue being the problem. If so neither light would light up.

Perhaps the issue is on the turn signal switch.

A multimeter can measure voltage on a bad connection and show 12v but with a load it would show 0 volts.

Does the emergency flashers work on both sides.

Have you recently changed out the turn signal switch?

The tail light is not wired through the turn signal switch but the brake is. Tail light is wired through the headlight switch, no connection between the two.

Are you sure you don't have the bulb inserted 180 deg around. Not easy to do but can be done.

. With brake applied left side tail light goes out,brake light stays on.Right side is not affected either way
What is meant by right side is not affected either way?

Also which side is acting up?
Also also can you say that the brightness of the tail lights is less than the brightness of the brake lights?
 
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The left side WAS first problem. Now both sides have no tail light. Both left and right side turn signals work. The brightness of the tail light was normal (when it came on)and brake light was also normal bright.Turn signal has been in several years.
 
Have you looked under the dash. Bet when you press on brake pedal you are moving wires under the dash from the headlight switch.
 
I see no wires moving around the brake pedal when brakes are applied. When i pulled the bumper awhile back there were light (thin) gaskets on the six(6) bolts holding the bumper on . I made new ones out of styrofoam could this be a problem? The original ones looked factory. Bottom line, still no tail lights. Brake lights come on.
 
Do you have power coming to the taillights and they're just not lighting up?
 
YES power to tail light. The brake element lights when applied,just no tail light
 
The taillight is a different circuit than the brake light and uses a different filament in the bulb. Those taillight assemblies had all kinds of socket and ground problems. If you're getting juice right to the bulb connector, either you have a bad or wrong bulb, or a ground connection issue.
 
There is a ground wire soldered to the outside of the bulb base,did factory do that?
 
I can't remember on that year. Is yours a plastic housing or metal? IIRC, it's metal, but, it's been a while since I worked on a '72 model.
 
In the later years with a plastic housing, they had a copper ring around the hole where the bulb holder went through. It had a separate ground wire that went into the harness. Those were famous for corrosion and bad grounds. The metal housing weren't as bad, but, still got corroded.....usually where the bulb made contact in the socket. I used to bead blast those sockets, blow them out, then spray them with lithium grease, install a bad bulb just to repaint the housing with some chrome spray paint, put in a new bulb, and then put it all back together again.
 
I believe it is plastic. I put a magnet on it earlier today and it did not stick. That piece is attached to the bumper.
 
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