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JoeK

High Beam/Low Beam at the same time?

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Maybe this is a dumb question, but I’m having a hard time figuring out my wiring. When you have the low beams on, it is just a single filament in each lamp. When you turn on the high beams, should the low beams filament also stay lit, or are they separate?

 

I’m rewiring my ‘71 with a new EZ Wire kit, and want to use the existing headlights and dimmer switches. As I understand it, the original setup not only uses a ground interrupt system but seperate fuses for each left and right headlight. Of course the ezwire kit isn’t set up for this, nor does it come with headlight relays. I don’t think I can use a relay kit made for the 240z because of the of seperate fuses per side in the original setup. Plus the ground interrupt makes it more complicated to my already confused state of mind. If the headlights should be all on when the high beams are on, that will help me to figure how to wire up a relay setup in some fashion.

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i do know there is a separate fuse for each side and i can check on the both at the same time for you i have that switch opened in my shop. thats the only way i can check now since i have never found a 240z diagram that is any where near correct.

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I'd have to check the 71 wiring to see if it is the same as mine, but here is how the headlights in a 77 work.

 

Each headlight has 3 wires.  +12v, a highbeam ground, and a low beam ground.  

 

Turning the switch to turn the headlights on, connects power to the fusebox which then sends (+) power via separate fuses to each headlight. 

The highbeam stalk changes which beam is grounded.  Both high and low are not grounded at the same time.  

 

I imagine you could energize both at the same time, but I'm not sure that the bulbs were designed for that and they might burn out quicker due to heat.  

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20 hours ago, Namor said:

I'd have to check the 71 wiring to see if it is the same as mine, but here is how the headlights in a 77 work.

 

Each headlight has 3 wires.  +12v, a highbeam ground, and a low beam ground.  

 

Turning the switch to turn the headlights on, connects power to the fusebox which then sends (+) power via separate fuses to each headlight. 

The highbeam stalk changes which beam is grounded.  Both high and low are not grounded at the same time.  

 

I imagine you could energize both at the same time, but I'm not sure that the bulbs were designed for that and they might burn out quicker due to heat.  

This has been my experience as well when I was redoing my headlight wiring to use relays.  I left it in the original configuration (even though it would be easy to wire it so that the low beam goes on when the +12v is applied and have it always grounded) for fear of overheating the bulbs

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Posted (edited)

I guess I need to figure out which bulbs I'm going to use, then find out how they are supposed to be run. I'm flipping the ground, so that the high selector will choose which gets the 12v, rather than the ground. The EZ Wire harness is set up this way, it doesn't even have any grounds, you have to supply your own. Thanks for the insights, keep 'em coming. 

Edited by JoeK

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The left and right was an older attempt at trying to keep the amperage a bit lower going through the steering column. I would take the time to convert to relays with your new kit. You can just steal the signal from either the left or the right wiring. Or in your case I guess just desolder one of the contacts on the particle board depending on how clean you wanted your harness to be.

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Posted (edited)
2 hours ago, KevvinG said:

This has been my experience as well when I was redoing my headlight wiring to use relays.  I left it in the original configuration (even though it would be easy to wire it so that the low beam goes on when the +12v is applied and have it always grounded) for fear of overheating the bulbs

I dont understand how would they come on if not grounded? but then there is still a lot i dont see since i have no wiring diagram.

Edited by ben a

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They are grounded through the beam selector stalk.  Each time you click it, it swaps between grounding the high and low beams.  If you just direct grounded the low beams, they would come on when you turn your headlights on and stay on when you turn on your highbeams.  As for keeping amperage down in the steering column, it didn't accomplish that at all because all of the power goes through the steering column.  I have a warped column cover because of it.  

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29 minutes ago, ben a said:

I dont understand how would they come on if not grounded? but then there is still a lot i dont see since i have no wiring diagram.

They will still be grounded, just at the headlight. Right now the 12v goes through the switch and off to the headlight while the ground goes through the selector. Instead the 12v will go through the switch then through selector and off to the headlight. I think its simpler really, or at least I want think that 😁.

 

I will definitely run relays, the contacts in the switches look tiny to me so I want to reduce the load on that side while also upgrading the headlights (likely to projectors with HIDs) 

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10 hours ago, seattlejester said:

I thought with two circuits of left and right it lowered the amperage a bit and let them use thinner wires to handle the load or something. Maybe my memory is failing me already.

Your memory is fine, it is 2 circuits but I'm pretty sure that all happens after the switch. The 12v+ goes from the battery to the switch to the fuse box, where it then splits up on it's way to the each head light. The high/low selector determines if high or low has a completed ground.

 

Go brighter headlight and you are drawing more amperage. Plus I'll be combining both sides on one fuse, since I'm using a new wiring kit. The new wires are much larger, but the switch is the same size so I think its a weak point. Also I'll be running 12v+ through the high/low selector, and ground will be constant at the headlight. But I'm a carpenter, not an electrician let alone an automotive electrical guru, so take it all with a grain of salt (or a salt lick). This all just how I understand it and am hoping someone smarter than me will read this and tell me I'm an idiot (nicely please).

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Headlight_Relay_Diagram.jpg

 

I think that is pretty decent. Very minimal amperage through the combo and high beam selector. 

 

30 is going to be your main power, this is going to be a thick wire (fused) from the battery, split to power both relays, one for high beam one for low beam.

87 is going to be your output power, this is going to also a thick wire going to the positive on the headlight, one relay will be the positive for low beam, the other will be the positive for high beam.

86 should be positive voltage I'm not sure if they just used a generic relay diagram and didn't want to flip it, I've heard some do not care the voltage direction, but I believe most want 86 to be positive. This is going to be power from the headlight switch (so put the positive signal wire to 86 on both relays)

85 is going to be the ground for the coil one would go to the ground signal for the low beam and one should go to the ground signal for the high beam.

 

The stalk for the blinker should be a ground selector as people have said. So when the headlights are turned on by twisting the combo switch that sends power to 86 (the combo switch is powered through the big wire going to the steering column). The blinker stalk should grounding the low beams normally which would actuate the low beam relay sending power from terminal 30 through 87 and completing the circuit for the low beam which is always grounded near the headlight. Pulling the blinker stalk should terminate the low beam ground for the coil and actuate the high beam ground which would complete the high beam relay coil circuit sending power from pin 30 through to pin 87 of the high beam assembly. 

 

If you wanted both the low and high beams on with the high beam (usually not on a stockish setup, modern cars with separate bulbs do keep both on, or cars with LED headlights will kick on additional lights), you could run a wire from the 85 of the high beam to the 85 of the low beam, but you would have to employ a diode to make sure the circuit would only be completed when high beam was on.

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