HELP! Headlight relay on fritz!

[commando1]

Sounds like a DPDT relay with a one pole NO and the other NC. Lol....

 

[Yatzee]

If I had a pic of the other half of the diagram (interior side of the bulk head connector) I can probably trouble shoot this issue. The ground for the lights is also the ground for the door motors so I think the lights actually come on before the doors open. There is a second power feed to the motor to close them once the lights are shut off. So I would think that there are two power feeds from the light switch to the doors and the headlights. What you need to know is what color of wire controls the doors and what color goes to the dimmer switch to change from low to high beam because it's the foot dimmer switch that controls the actual headlight relay coils only that you are installing.

 

[Big_John]

UGhg!! just checked the coloured wiring diagram from classic car wiring (917)8619131 and it shows the following.....................
green wire from hidden headlight relay goes to a splice to the beam selector switch the other goes to the light switch...simple which one is power?
The black wire goes to a splice to a 5 way.... one to the voltage limiter, one to the brake warning light???,oil pressure indicator???, one to temp indicator hot???, and temp indicator cold and ignition switch. Probably power.
The other two are the up and down wires for the headlight motor.

I am thinking that a normal relay is not the answer, I know that you can use a relay say to turn spotlights on and off but this relay needs to turn the up power on and then disconnect and when the headlight switch is turned off the relay needs to power the headlights down wire then disconnect or am I missing something.

Bob

I promised a sketch, but I'm having more pain issues tonight than usual and I'm gonna turn the TV on in a few and veg out.

First thing!! You do know that the key has to be on ignition or accessory for the headlight doors to work... right? That will screw you up if you aren't aware.

OK... Black is power, although in my 70, that wire is dark blue with a white tracer. Yes, it powers a lot of other stuff.... That's OK. Green is from your switch.

In my car, the door motor wires are dark blue with a yellow tracer and black with a red tracer.

Using a standard Tyco/Bosch relay, ground wire goes to terminal 86. Power wire (your black) goes to 30. Green to 85.

Your wires that control the motor goes to 87 and 87A. Up to 87 and down to 87A. I'll let you figure out which is up and down.

5 amp circuit breaker (like the factory) in the power line before the relay is a great idea.

This circuit should work and I apologize for the lack of a sketch. This will also only work when the key is on. If that bothers you, bring power from someplace else that isn't switched.

I was going to try something on my car tonight too... I'm not leaving the recliner until bedtime... I still have to work tomorrow too. Crap.

 

[Yatzee]

There is just one thing I need to know and I may have a solution. I studied the diagrams for your car that I downloaded and drew some interesting conclusions. In order to verify the possible solution I need to know what Painless kit (the number) and, with the sockets unplugged from the back of the headlights, weather the doors open and close normally like they normally would as if there were headlights connected. I have identified the wires by color code and the purpose they serve. Here are the diagrams in the event you don't have them. You can open and enlarge them with Windows viewer.

 

[Big_John]

There is just one thing I need to know and I may have a solution. I studied the diagrams for your car that I downloaded and drew some interesting conclusions. In order to verify the possible solution I need to know what Painless kit (the number) and, with the sockets unplugged from the back of the headlights, weather the doors open and close normally like they normally would as if there were headlights connected. I have identified the wires by color code and the purpose they serve. Here are the diagrams in the event you don't have them. You can open and enlarge them with Windows viewer.

I think I know where you are going with asking if the doors open and close with the headlights disconnected. That was one of the things I want to check myself. I was going to bypass my relays and try it. I think the door relay needs the ground feeding back from the headlight filaments to close the relay when the switch is turned off.

 

[Big_John]

I tried something last night.

With the relay hooked up, I turned the lights on. Low beam. Ignition switch on.

Doors opened. Lights on.

Turn off the switch.

Doors still open, lights still on.

I then ran a jumper from ground to the feed wire from the switch.

Doors closed, lights off.

So.... I think my theory that the headlight door relay needs to have the ground returning from the headlight relay rings true.

I have a couple solutions, but nothing "elegant and simple" just yet.

One other thing, I realized the key needs to be on "run" for the doors to work. "Acc" position does not work. I was incorrect about that.

 

[commando1]

I apologize for constantly interrupting you guys on this but I have a dumb question.
Isn't that Painless kit for single headlamp systems, not dual?

Seriously, maybe I'm being a pain in the *** here but I planned on doing the halogen + relay thingy with my 76 NYB and looking at the Painless kit I can't for the life of me see how that can work.

Also..
The ground from the headlamp has to be totally isolated from the ground from the relay because the ground in the relay is only grounded when the relay is powered by the headlight switch being in the on position. The ground for the headlamp and the motor as tied together in our systems would be affected by this. NO?

My idea of a correct relay wiring system for dual headlamps wouldn't come close to looking like the Painless kit.

Sorry. As you were...

 

[Big_John]

I apologize for constantly interrupting you guys on this but I have a dumb question.
Isn't that Painless kit for single headlamp systems, not dual?

Seriously, maybe I'm being a pain in the *** here but I planned on doing the halogen + relay thingy with my 76 NYB and looking at the Painless kit I can't for the life of me see how that can work.

Looks to me like their 30814 kit is for quad lights. Two relays etc.

I didn't use a kit.

Also..
The ground from the headlamp has to be totally isolated from the ground from the relay because the ground in the relay is only grounded when the relay is powered by the headlight switch being in the on position. The ground for the headlamp and the motor as tied together in our systems would be affected by this. NO?

My idea of a correct relay wiring system for dual headlamps wouldn't come close to looking like the Painless kit.

Sorry. As you were...

The headlights are grounded via the black wire to a convenient spot under the hood as is the door motor. The headlight switch does not provide grounding for the lights... or anything else. It provides power to the headlights and power to the relay.

I'd love to see a sketch of what you are thinking of.

 

[commando1]

I'd love to see a sketch of what you are thinking of.

I am going to scrutinize my existing setup on my NYB,
have a beer, think it thru, finish beer, and draw it out.
Hopefully tomorrow.

 

[commando1]

Here is how I would wire the headlights to operate off relays.
Any mistakes you can see?

 

[Yatzee]

Looking at the wiring diagram, the headlight doors connect to a delay relay of sorts, so yes you are correct, it needs to be grounded through though the relays to allow both opening and closing. I was curious if the flow of current or ground had anything to do with the relay that opens and closes the doors when the lites are not present. Great job on resolving the issue - patience is truely a virtue. Go have a beer.

 

[commando1]

Check out the finished diagram and see if anyone sees a problem.

 

[Big_John]

That would work as you've drawn it. The only thing I would do different is I wouldn't get the ground connection from the old headlight connectors. I'd run a wire (larger than stock) from the new headlight connectors directly to ground. Less connections to deal with and cause voltage drop etc.

I did mine a little differently and cut into the existing harness. I placed the relays under the speed control bracket and ran new (heavier) wire to the headlights. It's the same circuit.... just a little more work to make it simpler.

 

[commando1]

That would work as you've drawn it. The only thing I would do different is I wouldn't get the ground connection from the old headlight connectors. I'd run a wire (larger than stock) from the new headlight connectors directly to ground. Less connections to deal with and cause voltage drop etc.

I did mine a little differently and cut into the existing harness. I placed the relays under the speed control bracket and ran new (heavier) wire to the headlights. It's the same circuit.... just a little more work to make it simpler.

I'm confused, John. I thought I read that your setup didn't play nice with the headlamp door motor.

When you find out what is happening, please post it here.

I have a very similar issue in my 70 300. I wired in two relays. One for the high beams and one for the low beams. In my case, the low beams work, high beams work. Doors open, but do not close except when high beams are on. I didn't use a kit. It's a pretty simple circuit and I also ran larger wires to the headlights.

I think it's a feedback issue from the relay under the dash for the doors. I've tried isolating the relays with diodes from the switch feed, but that doesn't seem to work. I've put off figuring it out for now. It works, I just have to turn the lights off in high beam to get the doors to close. The FSM is a little vague about how that relay is wired, so I need to actually get under the dash and look at the wiring.

 

[Big_John]

I'm confused, John. I thought I read that your setup didn't play nice with the headlamp door motor.

It doesn't.

Everything I did is similar to what you are showing... I just eliminated plugging in the connectors.

Ground is ground.... It doesn't matter where the wires come or go to.... The ground isn't switched anywhere. If you follow the ground wires on the existing connectors, they just run up to a convenient spot on the inner fender where they pick up body ground.

What I need to make the doors work is to replace the existing door relay with a Bosch/Tyco unit that will give + power to the door motor up wire when the lights are switched on and +power to the down wire when the lights are switched off. The present relay does this now, but it appears that because there is no return ground through the filaments, the relay will not operate correctly.

After I figured this out, I did some digging and discovered the 68-70 Charger guys are having the exact same issue. The solution was the same as I came up with.... A new door relay to control the door motor.

What I'm probably going to do is put another relay under the hood and wire the door motor to that. The existing relay can just stay put under the dash. I'll unhook it. That way I can get to the relay without crawling around under there.

 

[Aussie 69"]

Great work Commando!! Does that mean that the original headlight door relay actually has 2 relays in it? I am not much of an auto electrician.

Bob

 

[Aussie 69"]

Hi Big John, Thanks for all that!! will try it out. Bob

 

[Yatzee]

My hat's off to you John. Patience is a virtue but brains are an asset. As far as the feeds to the lamps from the relays, 10 ga wire with the shortest distance to the lamps is best. My relays are on the left side of the rad support in a weather proof black box out of harms way. Nice call on the door relay.