Just installed a ez wiring harness in my 56 merc,I tried out the turn signals in the rear and they work but when I turn on the headlight switch they won't work at all, I'm a electrician and this has me mind fucked!! Also the brake lights won't work, everything is brand new except the turn signal switch..
I would start by making sure you have the turn signal wired properly as per the manufacturer's instructions.
Are the light housings mounted to the car or "hangin" be the wires? They need to be mounted securely to give a good ground.
The turn signals not working when the parklights are turned on sounds like a ground issue. On the brake lights are you sure you have the rear turn signal wires hooked to the taillights? With the turn sig switch off, you should be able to follow the power through the braklight switch into the turnsignal switch, and back out on 2 wires. These 2 are the rear turn-brake wires. Maybe you have the front signal wires hooked to the rear, so no brake circuit. Either follow the power through with a test light or hook up the front lights and see if they light with the brake switch. Also could be a bad turn signal switch, did the brake lights and turn signals work with the old wiring?
Almost all aftermarket wiring kits are GM friendly kits,GM's have two separate hot leads going into the headlight switch whereas Fords only use one.This problem has come up many times over in our Ford Group,contact EZ wires tech for a fix.When I did my Ford I used a GM switch and transferred the Ford knob to it which made it EZ to install the 4 way flasher unit.You really should hook up all wiring for proper system grounding.
When you say they don't work with the headlight switch on, does that mean nothing back there works, or are the tail lights lit? Any chance you wired the turning lights to the tail light filament, stop and turn usually share the same filament.
With the key in on position I have turn signals left and right,when I pull the headlight switch turn signals will not work,I'm using a gm headlight switch..
Like has been stated already make sure you have a good ground on each light. Your symptoms scream bad earths.
Is the battery fully charged? I had similar problems with a new wire harness and I was using a 12v power source. When I hooked up to a fully charged battery everything worked as it should.
Most turn signals quit working when one light is out,so if your front isn't connected would be like 2 lights out. That is just a thought. Jack
Bad ground or grounds. Powder coated light brackets must have coating ground away for good ground, as does fresh paint at grounding points. Just wired my F1, tail lights worked but only one brake light would work....powder coated taillight bracket was the culprit.
You might have the wires crossed at the rear lights as well. So you have the dim part of the bulb, the filament, as the turn and brake function so then when you add in tailights, it bright part of the bulb lights up and over powers the turn and you wont even see it blinking.
A rodder is right, turn signals look like they are working when it is actually the tailiights when the headlights come on they are using the brake light filaments which are brighter , therefor covering up the lower powered and dimmer tailights switch your wires .same thing for front parking lights and turn signal
I am having the EXACT same problem wiring my 50 Merc. Rebel Rodz Harness and stock 50 Merc Turn signal switch. Everything works except no brake lights and when I turn on the headlights I loose the turn signals. Did you figure it out? Thanks!
the turn signal/brake lights have nothing to do with running lights or headlights UNLESS like mentioned above you have bad grounds and the brake lights are being grounded through the unpowered running light wire OR as mentioned above, you may have the wires switched at the pigtale of your tail light
AHHH I'm pulling my hair out. I've triple checked everything I can think of. Could be the switch but I can't find a replacement switch anywhere. Anyone ever put multiple (More than 2 grounds) on their taillights?