Headlights On - No Front Turn Signals

Need more info. Did you replace the entire wiring harness ? if so with what ?
Just off the cuff, check your headlight grounds. Follow the double black wire from the right headlight back to where it attaches to other grounds on the right side of the body.

I rewired the entire car. Rebuilt the headlight and park lamp plugs up front with new wire and terminals inside. Headlight grounds are all good. Park lamp/turn signals are grounded through the plug. With headlights on and turn signal on, I ran a wire from the battery neg to the sockets for positive ground and no change.

I did notice when you look very closely that the filament for the turn signals lights and blinks very dimly.   It's not enough to notice through the lenses.

Honestly, they're old bulbs, but the turn and park lamp filaments both work so I didn't suspect them. I'll try replacing them anyway.

Try reversing the positive lead for the running lamp and turn signal. You may be powering the wrong filament for each. I believe there are just 2 positive power leads to the light, and ground is made through the housing.

Bob
tufcj

Edited by tufcj - Apr/09/2015 at 3:04pm

Tufcj is correct. The front turn signal / parking lights are grounded through the housing into the bumper and through the bumper brackets into the body. Check to see if you have continuity between the bumper and the body or better yet, from the bumper to the battery negative terminal. Keep in mind too that the battery negative goes to the block and the body ground goes from the engine block to the cross member with that heavy black engine to body ground wire.

The symptoms you're experiencing are classic grounding issue symptoms. Before rewiring for relays you should try your best to double check your wiring work. The turn signals, stop lamps and emergency flasher circuits are all inter related and the most complex wiring in the car.
The headlight circuit is independent of all the others and is fed directly from the headlight switch to the dimmer switch and then out to the lamps. I doubt that the headlight circuit is the issue as long as you can confirm the headlight and body grounds are good and solid. The turn signals and parking lamp circuits, while they share the bulbs themselves, are totally independent other than the shared ground. The turn signal and stop circuits ( the brighter bulb filament )all pass through the turn signal/ emergency flasher switch. Following tufcj's advice you may want to check the front turn signal wiring back to the turn signal switch. When doing any tests make sure the emergency flasher switch is pulled out ( off position ).

Good luck with your troubleshooting, this could be a tough one !

Have you replaced the switch? There is a difference between years. From the factory in 68 and prior, the parking lights remained on when the headlights were on. Rule changes in 69 had the parking lights turn off when the headlights were on. There could be a compatibility problem between the wiring and switch used.

Bob
tufcj