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Headlight High Beam Wiring

54K views 51 replies 16 participants last post by  Mumad 
2014 Hyundai accent. I installed a light bar but for the life of me, I haven't been able to figure out how to wire them up to the high beam. I've attached a picture of what I've done and how it is wired up as I type this. I have a feeling that I'm missing something simple, but my brain is fried from spending hours trying to figure this out. As you can see from the diagram, I have the ground for the illuminated switch AND #85 on the relay hooked up to the GREEN wire on the headlamp. I'm thinking this is where I've messed up. The switch works and illuminates properly on high beam, but it also illuminates and does NOT work on park light setting.

Now, I tried a million different combinations so I was rather confused at the end of the day, but one of them worked and I'm pretty sure it was when I had just the relay in place without the switch. I took the connector off the back of the headlight (drivers side, not that it matters) and tested each point at OFF, PARK, LO and HIGH. The results are on the picture. What messed me up is that on HI, the green wire (#1 in the diagram) does NOT go to ground. Or not a solid ground anyway. The other ones marked G were 100% definitive ground.

So my current train of thought is this: The ground on the rocker switch should go to chassis ground and #85 on the relay should go to the green wire (#1) on the headlight. The +12V for the switch shouldn't matter where it comes from since the red wire at the headlight connector is +12V at every setting. But if I do this, the switch will illuminate in the ON position even when the high beams are off because the power source and ground are not from the headlight. That's why I wired the two grounds (switch & relay) together in the first place so that the ground is provided when the headlight HI is switched on.

Anyway, I know this is a bit scrambled, so if anyone has any ideas or needs any clarification, let me know. Switch is at the bottom of the picture. Thanks!!
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I'm pretty sure the high beam uses a ground wire from the turn signal switch. Just splice into that for a relay coil ground and connect the rest hot with a fuse and to the light.
That's the way it is now, except the ground wire I used is at the headlight plug and it's hooked up to both the switch negative and the relay coil negative. Problem is, the rocker switch LED lights up when the light switch is off or in park. It shouldn't if the green wire (#1) was a true ground but as I mentioned above, it is not. For some reason, it works on a relay but when I put the rocker switch in there, it does not. If I take the negative off of the rocker switch, the switch will work properly, but won't light up. But maybe the ground you are mentioning off the multi switch is a true ground?
 
Is this with the rocker switch in the off position too?

Yes, but it's dimmer than normal.

Nor should it be when the light switch is off or in park. It should only be a true ground when the high beam headlamp is on. As your chart shows, it's +12V when the high beam is off.

Right, but it doesn't go to chassis ground when the high beams are illuminated. The multi meter shows an open circuit, definitely not a solid chassis ground.

It's the same ground as the one your connected to at the headlamp.

^though so, thanks for clarifying.

If I helped you fix it, why not...

Your support is greatly appreciated
 
I suspect the dim illumination of the LED is due to voltage drop across the resistance of the relay coil. To confirm, with the rocker switch off, connect a wire across the coil to short circuit it's resistance. If the LED goes out you know that's where the problem lies. Placing a diode (1N4001) in parallel with the relay coil might cure the problem. That would automatically short circuit the relay coil when the high beams are switched off...see below.


The meter is wrong then. The high beam control wire can't be open circuit to ground when the high beams are illuminated. If it was open circuit no current would flow and the bulbs wouldn't light up.
View attachment 461249

If I helped you fix it, why not...

Your support is greatly appreciated
I'll be away for a couple of weeks and I thought I'd have time to try this before I left, but I did not. I'll try it when I get back and see what I come up with although your explanation about the dim LED makes sense. The meter when set to ohms goes to 0 when I go to chassis ground. But when I go to the green wire when it's on high beam, it doesn't go to 0....I can't recall the exact number, but I think it was around 7000ohms.
 
Ok, I've got a couple of ideas. For some reason, I had a brain fart when I installed the lights and didn't realize there was actually a high beam relay in the fuse panel under the hood. On my 2006 Focus, I used the high beam relay as an input to the same LED illuminated switch for the same LED bar. It works perfect. The LED on the switch only lights up when the high beams are on and the switch is on. So when I realized there was a high beam relay in the Accent, I was like, "Voila!! I'm an idiot for not noticing this sooner!" So I went about testing the relay to see which input I needed to use to work the same way as the Focus, keeping in mind the high beams are negative activated. And that's where I realized I was in the same boat again. I completely 100% understand how a relay works on a regular 12V system. This Hyundai however has beat the **** out of me. I can't figure out the relay IN/OUT for the life of me. I've attached a diagram of what the pins are when the relay is in place and when it's removed. It makes no sense to me. Can anyone shed some light on this and how the relay triggers? NOTE: I'm not 100% sure the pins are numbered properly!!
 

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I'm an AUTOSPARK by trade and your measurements make no sense to me either :)
And I see your using that ohmmeter again. Did you not read my previous post?

Did you ever try shorting out the light bar relay coil like I suggested in post #36?


If I helped you fix it, why not...

Your support is greatly appreciated
I did....but I only had enough time to do one thing. And since I had my brain-wave on the relay, I figured that would be the one I was going to try. In the next few days I'll be able to get at the car for more than an hour and I'll go through everything, including post #36. I'm not sure what an AUTOSPARK is, to be honest. But I see you have some serious knowledge. So in the meantime keeping in mind that I only want the LED light bar to come on with the high beams, but on an illuminated LED switch, I'll ask you this: how would YOU wire this up?
 
I also have 17 years of experience as a two-way radio tech and installer and it's frustrating that with that amount of experience, I haven't been able to figure this out. But I will, hah! I've attached two pictures of the under hood fuse panel and cover showing which relay is for the high beams. And it's the right relay for sure. Remove the relay, the high beams don't work, put it back and you can hear and feel the coil activate the internal switch on the relay and high beams come on. Also, this is a Canadian car so maybe that's why you couldn't find it? I'll be looking at #36 in a couple of days when I'm off work. Hopefully that will get it done. If not, my back up plan is to use a 2nd relay and take the output of 87 from the first relay and use that as an input to the illuminated switch, then run the second relay off the switched power.
 

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Are Canadian models fitted with DRLs like cars need to have in cold climate regions of Europe? I'm just wondering if the relays are perhaps added when the car has DRLs. The RB Accent wasn't sold here in the UK. So I think my diagrams are actually for US models. Both the headlamp relay slots are empty on my diagrams.

If I helped you fix it, why not...

Your support is greatly appreciated
Yes they are fitted with them, this one is as well.
 
View attachment 461672

Euro schematic, headlamps 12v hot, gnd switched
Excellent! So.....if I'm reading this right....and I may not be, I'm at work and it's 3:17AM right now, the high beam relay (RLY 2) pulls the circuit to ground, completing the connection and lighting up the high beams. And this is indicated by the green wire on pin#1 of the relay which would likely be the same green wire I have tapped into for the relay control. Does that make sense?
 
Yeah, that's how it works. But I still don't understand the readings you were getting at the relay socket. According to the diagram the relay 87 terminal is tied to ground. Yet somehow you managed to measure +12V on it. That doesn't make sense.

If I helped you fix it, why not...

Your support is greatly appreciated
No kidding. That's the baffling part to me as well. I just re-checked the relay with a different, better quality meter and the readings were the same. I work tonight, but tomorrow I'll have some time to spend on it. If I have time, I'll post a video or pics showing the readings. Red Raspberry posted above about computer grounded circuits......I'm not familiar with those. I'm thinking that's why the green h/light wire shows +12V and then goes to ground when the high beam is activated. Could be why this relay is doing the same thing.....although why 30 and 87 go to 1v is even more f'd up. If that theory was right, then they should go to ground; and 87, which should be the green wire I tapped into should show the same, 1V. I'll double check that tomorrow. But at this point, I really don't know.
 
Ok, final update, thank christ. After way too much messing around and not nearly enough beer, it's wired in and working. After trials and tribulations, I ended up going with the 2 relay system. The fault with just the single relay seemed to come down to the green (ground) wire on the plug at the back of the headlight. It works to trip the relay, but not to run the LED on the switch. I believe if I didn't want to use an illuminated switch, then it would have worked. But I had to be difficult and use the illuminated one. I've posted pictures of the install, including the switch. Note that in the pictures there are two switches. The top is for the light bar, the bottom is for the fog lights (not factory). Only the light bar is wired into the high beams. I don't have a picture of the schematic I used, but I'll add that after. If anyone wants any info, let me know. Thanks everyone for your help.
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