Ok. So I’ve installed the Holley retro lights and on bright, the lights will go off and on, the doors won’t open and close, etc. you can hear the relay under the dash clicking each time. So, I was at a car show and the sales rep from United Pacific led gave me a part number for a 15 amp load resistor. Has anyone used these with success? I’m wondering if it will heat up my wires just like the old incandescent bulbs?

what vehicle are we talking about, and is any part of the headlight harness on relays ?

Sorry. It’s a 70 Charger with the electric headlight doors and relay under the dash.

...

Well it does affect the doors. I found a thread on b bodies and he had the same problem. He installed a 6 ohm resistor on both low beams and fixed the problem. My source said to use a 15 ohm resistors. Another guy replaced the oem relay with a Bosch 5 pin and cured his. I think the oem relay just has to have resistance to operate the motor just like a flasher needs more than a led light to flash the flasher on and off.

Any headlight conversion IS SHOULD NOT represent any disturb to the headlights doors system. Both systems works Independently one from the other. You can open and close doors even WITHOUT headlights installed. The only point they share is the lights on signal coming straight from headlight switch (light green wire) to trigger on/off the doors. But from there is a parallel system between them, not a serial system to affect each other.

For me problem could be elsewhere…

Some power return from led system? Maybe

But the need for some resistance or load at headlights system to make the doors work? Doesn’t make any sense, since as I told, the doors system works even without headlights installed.

A Diode to block some power return from the conversion? Maybe


A dare to anybody here try to make the doors work unplugging the headlights… and will confirm the doors will work the same. That’s an easy test.

That’s an idea I have not thought of. I’ll try that next. I tried the relay harness from crackedback and it did funny stuff as well. The headlights would stay on sometimes when turned off and you had to hit the dimmer switch to get them off. One thing strange is when I turn the switch off, it will have a dim glow in the low beams until I turn the ignition switch off. There is some kind of a bleed back in this system. It has to be something with the led bulbs because everything works properly with regular headlights. It’s got me perplexed.

Yeah, LED lights do that sometimes. It's leakage current. Not enough to light up an incandescent bulb, but enough for an LED. My microwave does that. Replaced the burnt out incandescent with an LED version and there is no "off" anymore. Just dim and on. Unless I lose power then it is off even after the power returns, until I turn the light on and it goes back to the dim and on mode.

I wonder if your headlight doors and headlights share a ground path and that is where the issue lies? Don't forget electricity requires a supply AND a return, most forget about the return side.

It's not my harness that caused the issue. My kit, same as the LEDs, helped identify an issue somewhere else in your lighting system. It's 99.9% the door relay under the dash or a ground that is loose somewhere.

The door system is independent of the headlights and activates off the green wire headed into the door relay.

Cracked back, you misunderstood me. Your system did not CAUSE the problem because there is nothing WRONG with your relay system. Your system does exactly what the led lights do. They both reduce the ohms to the wires and connections and thus reduce heat and the problems these cars have even when new, let only when the are old and corroded. The problems are occurring because this old relay must require the ohm resistance created by the oem incandescent lights. The same problem occurs when you put led bulbs in turn signals. They hyperflash.

So, I unplugged the headlights and the headlight doors worked several times with the headlight switch and the key in the on position. After a about 5 cycles, they would no longer work. They only worked consistently when the motor was running. I stopped at 15 tries and they still worked. I plug in the led lights and honestly, things are so inconsistent, it’s hard to describe what they do. I can make the doors go up and down by just hitting the dimmer switch. They do that even inconsistently. The thing that really bothers me is when I am in high beam driving and the lights flash on the off. They do not do that on low beam if I leave it there.

So, I can tell you this. I unplugged all the led lights and plugged in two oem incandescent on one side. Everything worked perfectly just like it should. I am coming to the conclusion that the relay needs all that resistance to operate properly. That is all it can be. A guy on b bodies had the same problem with his 70 Charger and the replies give me two options to try. One is two load resistors on each low beam side or a new Bosch 5 pin relay. I’m leaning to the relay because that makes sense that it will be easier on my wires. That is the big benefit I’m looking after.

So driving home tonight, I left the headlight motor wired up and all 4 leds plugged in. I drove home on low only, pulled into the garage, hit the brights and then turned off the headlight switch. The doors closed and the low beams have a low glow on them. I turn off the key and the low glow stops.

It’s got to be feedback in this relay so changing it to one compatible with led light seems the most logical. There is a diagram to follow on b bodies so hopefully I can resolve this. Thanks for ever help. I’ll post my fix.

Once again, no need for any resistance to make it work. But as Crackedback mentioned COULD be a ground issue at hideaways relay? Maybe. That could make also not make it work with engine off after 5 cycles.

IMHO TIPICALLY Any inconsistent system work points out to a ground issue

Forgot to mention… not just the ground of the relay with dash frame/chassis, but the relay itself internally with its own chassis.

Try first cleaning the factory relay bracket and the area where is mounted on dash frame.

Relays do not require resistance to function. What flashers do with LEDs installed is irrelevant, the original style flasher uses a bimetallic strip that requires a certain amount of current flow through it to work. Relays do not work like that.

As I mentioned, it's likely a grounding issue. I suspect the correct ground path is compromised to some extent and with the incandescent bulbs installed the normal path to ground is still the least path of resistance. Once the LEDs are put in place the normal path is no longer the path of least resistance and you are now getting wonky behaviors.

So I dug out my copy of the 70 FSM for a Charger and apparently the CIA thinks it's top secret info or something as large sections of that circuit are blacked out, lol. Near as I can figure, the ground for that relay is the mount to the dash frame. I would make up a long jumper and temporarily ground the case of the relay to the battery negative and see if that sorts it out. The guy that said a Bosch relay fixed his problem had to make a new ground for it and that probably fixed the issue for him. Another potetial ground issue is internal to the relay, the coil has to be tied to the case ground and that might be dirty or otherwise compromised. I mean, it is 50+ years old.

Yes. All good ideas. I’ve got work to do on this. I got in the car the other day with the lights off and turned the key to the on position and the doors opened up. I hit the dimmer switch and they closed.

Correct… because the LED is indeed a Diode (Light Emision Diode) what becomes a just one sense power path, blocking the ground path posibility for the relay if the relay is getting a bad quality ground by itself..

Weird because the Headlights door relay trigger is before the floor beams selector… light green wire is allways powered (the trigger for the doors) as soon you turn on the headlights… then the floor beam selector just routes the power to the violet wire for lows, or to the red wire for highs.

Ok. I’m getting this solved today. I’m sitting in the car doing tests. I’ve check all my grounds in the headlight harness and grounded the relay under the dash from case to the battery with a jumper with No headlights hooked up at all. Doors are open. Key off and turn headlights on. Dash and parking lamps come on. Push dimmer switch and nothing happens except red dash light comes on bright. Now key on test. Switch on and parking lamps are on and it in low beam position. Push dimmer 20 times and nothing happens except red light in dash comes on bright. Ok. Now I can get the doors to open and close with the dimmer switch. I have to turn the key on, leave the light switch off and hit the dimmer switch. They close and the red light in the dash had a faint glow. It appears they are open on high but closed on low. If I disconnect the ground from the relay, it makes no difference on anything I’ve tried.

Here’s something new. As soon as I plugging the one incandescent headlight, with the key on and the doors open, the doors close. The switch is off. That’s just like it should be. So with one incandescent and no led lights, everything works as it should I can’t make the headlight doors open or close with the dimmer switch. With the relay grounded or not, it makes no difference.

With the 4 leds all hooked up, it goes back crazy with or without the ground. You can only get the doors to close on high beam. They will open on low but only close on high. I’m not going to drive it with high beams on at night because they were completely going on and off. They will stay on when the lows are on.

So, I’m getting the new five pin relay wired up and we will see.

So today after all the testing, I installed a five pin relay. I’ll post the picture from the forbbodiesonly post from Kerndog. It solved all the problem.