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I'm working on this same issue. I've discovered the light blue wire from the body integrated unit to the headlight has 12v when the high beams are activated. Do you think it'd be safe to use to operate a relay?
534424
 

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G'day & Welcome aboard @4inAnSTi

Without understand any diagnostics affects I'd say it would be OK.

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I would not drive a relay from the BIU for 2 reasons:

- The BIU's current drive capability is not specified. We have seen cases where people overloaded the BIU by adding additional incandescent lights to a circuit.

- Even worse, inductive kick can send a big spike back into the BIU when current to the relay is released. I addressed this in my Relay Tutorial thread a while ago:

It’s a fact of electronics that when power is removed from a coil of some sort (such as in a relay), the collapsing magnetic field induces a current spike in the opposite direction of the original flow of electricity. It’s called inductive kick. Though brief, this spike can be of significantly higher voltage than the amount that was originally there, and it can puncture sensitive electronics that might have been a part of the coil’s drive circuitry. Things like those expensive sealed modules.

Try this in your garage some night: Hook up a relay to a source of power, shut the lights off, and then remove one of the wires. Big spark!
Zap! Fry! $$$!

Take a look at relay assemblies intended for use with microcontrollers like Arduino or Raspberry Pi, which contain circuitry such as an optoisolator or a transistor to safely drive the relay in response to a low current signal. They can be powered by either 5 or 12 volts, as specified (so get 12), but be careful to check the trigger voltage. It's probably 5 volts since it's intended to be controlled by a computer, so you might have to experiment with a series resistor to safely trigger it with 12. These are available on eBay with 10A switching capability for as little as $1.77, from China (naturally).

As for a high beam signal, how about the high beam indicator light? Though probably kind of hard to get to.
 

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Great feedback. Thank-you @bbottomley, that's very helpful.

I got in touch with a couple engineer friends and I'm going to go over to their shop and figure something out. One suggestion they had was a current sensor on that wire. Whatever we come up with, I'll definitely report back here.
 

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I should have noted that you can combat inductive kick by connecting a diode across the relay coil, facing toward the positive end. But the problem of unspecified current drive capacity remains. And if your diode should decide to die, so too shall your BIU.
 

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Yup. After more discussion and consideration, I think I'm going to go with a sensitive solid state relay on the blue wire. We also looked at using the grey wire on the dimmer switch but it's not overly accessible. This is the relay we're intending to use since he has them at his shop and they should do the trick. Probably overkill but should cover our bases.

D1D40
 

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While you have the dream team assembled, can you guys also look into deactivating the DRLs on factory LED headlights? 😁

Usually is a resister pack disconnect on the incandescent ones, but on the LEDs not sure if pulling the DRL pin in the connector is enough or it more is required...
 

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Any chance of you taking a few instructional photos on how you do it please?
Possibly. I'll be imposing on a friend's shop so I'd like to minimize my time there. I'll try to snap a few pics here and there but don't expect a documentary. :geek: I'm heading there tomorrow. It's over an hour drive and we have some rally cross event organizing items to discuss too so could be a long day.
 

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While you have the dream team assembled, can you guys also look into deactivating the DRLs on factory LED headlights? 😁

Usually is a resister pack disconnect on the incandescent ones, but on the LEDs not sure if pulling the DRL pin in the connector is enough or it more is required...
Um, no. DRLs have a purpose. Why disable them?
 

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Um, no. DRLs have a purpose. Why disable them?
They do have a purpose, but the way Subarus are wired you always have the option of DRLs. If you leave your lights switched on, they go out when you power off the vehicle, and then come back on when you start the vehicle.

I see your concern, but I hope to explain how lights at certain times is also a safety risk.

I always drive with my lights and yellow fogs on as silver cars "disappear" at dawn and dusk.

That said, I enter facilities where I am expected to turn off my lights for safety reasons (not blinding guards at military bases, for example) and also entering my garage is more dangerous due to the amount of glare.

It's not taking away anything, rather it's adding capabilities.
 

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They do have a purpose, but the way Subarus are wired you always have the option of DRLs. If you leave your lights switched on, they go out when you power off the vehicle, and then come back on when you start the vehicle.

I see your concern, but I hope to explain how lights at certain times is also a safety risk.

I always drive with my lights and yellow fogs on as silver cars "disappear" at dawn and dusk.

That said, I enter facilities where I am expected to turn off my lights for safety reasons (not blinding guards at military bases, for example) and also entering my garage is more dangerous due to the amount of glare.

It's not taking away anything, rather it's adding capabilities.
We probably won't have any time to look into it. That said, there is a 10A fuse labeled "DRL" on the dashboard fuse panel, #23. Have you tried pulling it?
 

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Yup, still worked. One of the more active people on here posted his rework of active headlights (steerable) and identified a DRL wire, but haven't pulled that out of the plug yet.

Other years they found removing a leg on a relay did it, but there are so many sensitive electronics, it makes me reluctant to start experimenting.

No worries. If you guys discover something in the process of your work, be cool if you shared it. I have the faith the internet will solve it eventually, just tired of explaining to military police why I blinded all of them... LOL
 

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Yup, still worked. One of the more active people on here posted his rework of active headlights (steerable) and identified a DRL wire, but haven't pulled that out of the plug yet.

Other years they found removing a leg on a relay did it, but there are so many sensitive electronics, it makes me reluctant to start experimenting.

No worries. If you guys discover something in the process of your work, be cool if you shared it. I have the faith the internet will solve it eventually, just tired of explaining to military police why I blinded all of them... LOL
We're way off topic here but I looked at the wiring diagrams and there are two configurations: responsive and non responsive. Looks like the responsive lights use the #23 fuse and a relay but the non-responsive ones don't. For those, it's a direct line from the BIU to the light housing on pin #5. It's a purple wire. I'll ask my colleagues but I would think just removing that wire would do it?
 

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That sounds awesome!

You have a good point, so back to the topic at hand! After a bit more study and reconsidering my solution from a previous post, I bought one of these to give me a hard hi beam trigger:


Australian law requires it for auxiliary lighting, so they have a commercial solution.

Hated dropping $100 on it, gotta pay to play. (Shipping from Oz to US was a fortune, but I found a UK distributor).

The CAN system just makes it so complicated and the wire diameters used are so thin that tapping them give me concern about breaking them.

The plan is to run thin wires out the back of the driver's side connector to the CAN module and hope for the best...
 

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Success! Worked like a charm. I didn't take any pictures while working because: A) I forgot my phone at home, and B) my hands were completely covered in grease while working on it because I had the car under-oiled to deal with the ridiculous amounts of road salt they spread around here and you can't not get dirty working in the engine bay and fender areas. Very messy.

I'll take some pictures and maybe an electrical diagram when I take it all apart again. One of the new driving lights has a broken connector so I'm getting a warranty replacement. C'mon USPS, get it together! Hasn't moved in four days!

But in summary, yes, you can use the light blue wire in the diagram above on the headlight connector to trigger aux lights with the hi beam switch but you need to use a sensitive relay that's isolated. Do not use a typical automotive relay. The D1D40 relay worked for me. I'm sure there are other options. FYI - we measured the current on the blue wire when the hi beams were on it's only 300mA and 12v. It's most likely canbus.
 

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Success! Worked like a charm. I didn't take any pictures while working because: A) I forgot my phone at home, and B) my hands were completely covered in grease while working on it because I had the car under-oiled to deal with the ridiculous amounts of road salt they spread around here and you can't not get dirty working in the engine bay and fender areas. Very messy.

I'll take some pictures and maybe an electrical diagram when I take it all apart again. One of the new driving lights has a broken connector so I'm getting a warranty replacement. C'mon USPS, get it together! Hasn't moved in four days!

But in summary, yes, you can use the light blue wire in the diagram above on the headlight connector to trigger aux lights with the hi beam switch but you need to use a sensitive relay that's isolated. Do not use a typical automotive relay. The D1D40 relay worked for me. I'm sure there are other options. FYI - we measured the current on the blue wire when the hi beams were on it's only 300mA and 12v. It's most likely canbus.
So, it's as simple as connecting to this wire?
534684
 

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So, it's as simple as connecting to this wire? View attachment 534684
Looks like it. Bottom row, second pin from the left. The wire looks more white than blue on my car.

However, it looks like you have the "strong responsive" lights as I only have an 8-pin connector there with only 4 wires on it. There doesn't appear to be a separate wiring diagram for those lights so, in theory, it should function the same but you probably shouldn't take my word for it (disclaimer time).

The only modification I made to the wiring harness was to splice another wire to that one and run it to the positive terminal of the relay's input. My setup was a bit more complicated because I added a kill switch on the dashboard but it's not needed. I'll make another post with pictures.
 
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