Help wiring auxiliary lights with high beams

[highfructose]

This is probably an easy question, but hoping someone can help.

2011 Lexus LX570…I ran a tap a fuse to fuse 55 (high beams) and then used that 12v that is “on” when my high beams are on to the “on” side of the relay that runs my nilight auxiliary driving lights.

The idea is that when I turn on the high beams, it’ll send a little current of 12v to the relay which will then “instruct” the spot/auxiliary driving lights to turn on.

And it works.

The problem is that because the Lexus has daytime running lights, the high beams ALWAYS receive about 12v when the low beams are off…so if I turn off my low beams, it turns on my auxiliary driving lights.

I don’t mind running w my low beams on all the time…but it would be nice to have a hack to turn off the daytime running lights or use another fuse, etc.

Anyone know an easy way to turn off daytime running lights?

Solution:
Within the in dash operating system/touch screen, you can disable daytime running lights. This allows me to run my auxiliary lights to automatically turn on with the high beams only.

 

[TeCKis300]

As you're finding out, the stock logic matrixed with the complexity of multiple overlaid control strategies including switching grounds makes this a tough problem without a clean solution.

It's worth hacking. Having all 3x pairs of lights (low, high, dogs) is awesome at night.

Here's some additional info in this thread that might help.

Running Fog Independent of Headlight

This is a riddle that's brought up from time to time - How to enable running the fog light without the headlight being on, with the factory fog light switch. Factory logic, allows fogs to function only when the headlight is on. I'd like to turn them on independently at times. I've made this...

forum.ih8mud.com

 

[cboyd]

Despite the complex discussions linked, I solved this by also adding a switch to the panel that controls the source of the power through the relay. This way when I don’t want the driving lights to be on, I just make sure that switch is off. Nice for DD mode when you don’t want to worry that the aux lights come on.

The while off road or desolate driving, you can control the aux via the stalk.

To be clearer, the main circuit through the relay terminates in the dash switch. The high beam source is the relay trigger as you wired it.

Did the same for my light bar on my 100 series. Control via the fog switch with a relay, but a dash switch makes sure it doesn’t come on while on-road.

 

[highfructose]

Despite the complex discussions linked, I solved this by also adding a switch to the panel that controls the source of the power through the relay. This way when I don’t want the driving lights to be on, I just make sure that switch is off. Nice for DD mode when you don’t want to worry that the aux lights come on.

The while off road or desolate driving, you can control the aux via the stalk.

To be clearer, the main circuit through the relay terminates in the dash switch. The high beam source is the relay trigger as you wired it.

Did the same for my light bar on my 100 series. Control via the fog switch with a relay, but a dash switch makes sure it doesn’t come on while on-road.

You seem to know about about electrical things.

Would a “resistor” of some sort work in between my tapped fuse and relay? To make it so it takes a full 12v to get past the resistor and then hit the relay thus turning on the driving lights?

For some reason I think the daytime running lights may not run on a full 12v…which is why led bulbs in my high beams don’t light up for the DRL feature…the volts aren’t high enough to power the led’s but would be to power the oem halogens, albeit at a lower luminosity (or relay I ran from the same circuit to activate my aux lights)

 

[Clyde S Dale]

Despite the complex discussions linked, I solved this by also adding a switch to the panel that controls the source of the power through the relay. This way when I don’t want the driving lights to be on, I just make sure that switch is off. Nice for DD mode when you don’t want to worry that the aux lights come on.

The while off road or desolate driving, you can control the aux via the stalk.

To be clearer, the main circuit through the relay terminates in the dash switch. The high beam source is the relay trigger as you wired it.

Did the same for my light bar on my 100 series. Control via the fog switch with a relay, but a dash switch makes sure it doesn’t come on while on-road.

This is what I did and it works fine. 2011 LX to clarify.

 

[cboyd]

You seem to know about about electrical things.

Would a “resistor” of some sort work in between my tapped fuse and relay? To make it so it takes a full 12v to get past the resistor and then hit the relay thus turning on the driving lights?

For some reason I think the daytime running lights may not run on a full 12v…which is why led bulbs in my high beams don’t light up for the DRL feature…the volts aren’t high enough to power the led’s but would be to power the oem halogens, albeit at a lower luminosity (or relay I ran from the same circuit to activate my aux lights)

I do know for a fact on the 100-series, that MrT used a "resistor pack" to essentially dull the voltage for the DRLs. It was usually a PITA, because they mounted that pack under or in the spot everyone mounted their dual battery... that said, I haven't dug in enough to know how it's done on the 200, but probably similar.

I suspect you could do something as you describe, but when tapping factory stuff, I dont like to mess with voodoo. back-feeding or other current anomalies make nasty things happy - least of which is some gripe of a system module, most of which is an expensive christmas-tree display on the dash requiring diagnosis. I stick to the easy path and let a little voltage be the signal wire. The rest i handle myself so as to know how things are supposed to run.

Also, i like the xtra step of fail-safe on the aux lights. All the bro-dozers and mall-crawlers having been running around with their light bars on lately, so I can image some State Police commander sending an edict soon to cover all off-road lights. I noticed e bunch of guys with covers on theirs in NH, so maybe that's happening there already...

 

[highfructose]

I do know for a fact on the 100-series, that MrT used a "resistor pack" to essentially dull the voltage for the DRLs. It was usually a PITA, because they mounted that pack under or in the spot everyone mounted their dual battery... that said, I haven't dug in enough to know how it's done on the 200, but probably similar.

I suspect you could do something as you describe, but when tapping factory stuff, I dont like to mess with voodoo. back-feeding or other current anomalies make nasty things happy - least of which is some gripe of a system module, most of which is an expensive christmas-tree display on the dash requiring diagnosis. I stick to the easy path and let a little voltage be the signal wire. The rest i handle myself so as to know how things are supposed to run.

Also, i like the xtra step of fail-safe on the aux lights. All the bro-dozers and mall-crawlers having been running around with their light bars on lately, so I can image some State Police commander sending an edict soon to cover all off-road lights. I noticed e bunch of guys with covers on theirs in NH, so maybe that's happening there already...

In the places I drive in the southeast, you cannot have uncovered auxiliary lights facing forward on the vehicle…and you certainly cannot drive with them activated on the road.

In practice, no one covers them and a fair amount of people use them on road.

I plan to leave mine uncovered and only use them when the high beams are on. Should be fine…and the added “safety” of an unbelievably bright set of high beams (in the aux lights) will counter the potential that an officer chooses to ticket me in my opinion.

Seems like I’ll just need to leave my low beams on all the time…no simple way to use the high beams as the switch without having the daytime running lamps also “switch” my relay…unless I get a tech stream and turn off the day time running lamp feature.

Wish there was an IOS app for tech stream.

 

[highfructose]

For anyone following, the solution was that the Lexus operating system in the touch screen has the ability to turn off the daytime running lamp feature.

So to run aux lights that automatically turn on with the high beams, run a fuse tap to get 12v from one of the high beam fuses (I used a 5a fuse) and run that as the 12v “on” circuit to the relay you’re running your aux lights off of.

 

[LXinOBX]

Despite the complex discussions linked, I solved this by also adding a switch to the panel that controls the source of the power through the relay. This way when I don’t want the driving lights to be on, I just make sure that switch is off. Nice for DD mode when you don’t want to worry that the aux lights come on.

The while off road or desolate driving, you can control the aux via the stalk.

To be clearer, the main circuit through the relay terminates in the dash switch. The high beam source is the relay trigger as you wired it.

Did the same for my light bar on my 100 series. Control via the fog switch with a relay, but a dash switch makes sure it doesn’t come on while on-road.

Having a senior moment here....for the life of me, I'm struggling with identifying the specific location to "tap" a grounding point for the Hi Beams.

My current thinking is to 12v + out of the 15 cig lighter fuse in cabin (it's acc switched?) ---> to dash mounted switch --> through firewall to relay terminal #86. My confusion is on the #85 terminal side....where does one actually tap into the hi beam circuit to ground that terminal (#85)? Would tapping the negative wire of the lo beam (literally right after it passes through the bulb) be the thing to do?

Hope the question makes sense.

Jeez, I'm being slow...appreciate any help!

EDIT: of course, DRL's switched off

 

[highfructose]

Having a senior moment here....for the life of me, I'm struggling with identifying the specific location to "tap" a grounding point for the Hi Beams.

My current thinking is to 12v + out of the 15 cig lighter fuse in cabin (it's acc switched?) ---> to dash mounted switch --> through firewall to relay terminal #86. My confusion is on the #85 terminal side....where does one actually tap into the hi beam circuit to ground that terminal (#85)? Would tapping the negative wire of the lo beam (literally right after it passes through the bulb) be the thing to do?

Hope the question makes sense.

Jeez, I'm being slow...appreciate any help!

EDIT: of course, DRL's switched off

I ran the hot/trigger/switch for the relay that drives my aux lights right off the wire that leads to the headlight if I remember correctly…

The hot/ground for the lights themselves I ran straight to the battery.

The relay is the “switch” that turns on the lights…the “automatic” trigger for that relay was the high beam wire just south of the headlight…it’ll receive juice when you flip the stock on steering column…which will then instruct your relay to send 12v to your aux lights.

 

[LXinOBX]

…the “automatic” trigger for that relay was the high beam wire just south of the headlight…it’ll receive juice when you flip the stock on steering column…which will then instruct your relay to send 12v to your aux lights.

Don't you mean (if tapping the wire south of the hi beam) that flipping the hi beam stalk will take the circuit to ground and energize the 30/87 side of the relay (resulting in bar ignition)?

Appreciate it! Hope I'm making sense!

This is the diagram I'm following - I'm interpreting the "upper left" portion to indicate I tap south (as you say) of the hi beam (the neg side)

 

[highfructose]

Don't you mean (if tapping the wire south of the hi beam) that flipping the hi beam stalk will take the circuit to ground and energize the 30/87 side of the relay (resulting in bar ignition)?

Appreciate it! Hope I'm making sense!

This is the diagram I'm following - I'm interpreting the "upper left" portion to indicate I tap south (as you say) of the hi beam (the neg side)

View attachment 3559468

I’m probably not the right person to advise on this as I’m a subpar mechanic…don’t fully understand the terminology, etc.

The headlight high beam has a hot and ground going into it…I think I cut the insulation off a small bit of the hot wire and ran a wire from there to the switch part of the relay (the thing that tells the relay to close its circuit/send power).

Then…if I pull the stock to “turn on” my high beams, not only do the high beams get power…but a little trickle comes off of it via that wire I installed and goes to my aux light relay which “switches on” the relay tells the relay to send power (since it’s wired directly into my battery and thus has access to power whenever) to my aux lights.

The way I understand relays is it’s an automatic switch…it uses a little trickle of 12v to act as a switch and allow for a big current to flow.

 

[LXinOBX]

I’m probably not the right person to advise on this as I’m a subpar mechanic…don’t fully understand the terminology, etc.

The headlight high beam has a hot and ground going into it…I think I cut the insulation off a small bit of the hot wire and ran a wire from there to the switch part of the relay (the thing that tells the relay to close its circuit/send power).

Then…if I pull the stock to “turn on” my high beams, not only do the high beams get power…but a little trickle comes off of it via that wire I installed and goes to my aux light relay which “switches on” the relay tells the relay to send power (since it’s wired directly into my battery and thus has access to power whenever) to my aux lights.

The way I understand relays is it’s an automatic switch…it uses a little trickle of 12v to act as a switch and allow for a big current to flow.

Appreciate the help, but yep, I get that (relay operation, toyota neg ground switching, et al). It's the actual "tap" point (where you guys are pulling off the hi beam circuit). IN your use case, you are pulling off the hi beams +12v.....I already have 12v flowing from the cabin (through a dash mounted on/ off switch) ...I need a hi beam "to ground" point so when hi beams invoked, the circuit "energizes" and ignites the 30/87 "side' of the relay.

Anyone? I'm totally overthinking this for sure....I tap the hi beam circuit on the ground (negative) side of the hi beam, correct?

 

[marques]

I ran the hot/trigger/switch for the relay that drives my aux lights right off the wire that leads to the headlight if I remember correctly…

The hot/ground for the lights themselves I ran straight to the battery.

The relay is the “switch” that turns on the lights…the “automatic” trigger for that relay was the high beam wire just south of the headlight…it’ll receive juice when you flip the stock on steering column…which will then instruct your relay to send 12v to your aux lights.

The way to do this and keep the DRL function is to power the coil of the new relay off the low beam power, and to tap into the switched ground that activates the high beam relay for the other side of the new relay's coil. This way the auxiliary high beams will only come on when both low and high beams are on. During the day, the low beams are off, so the aux. high beams won't turn on, even if the DRL are on. A manual switch in series with the coil's ground on the new relay will allow you to enable or disable the auxiliary high beams so they don't necessarilly run all the time the high beams are on.

You don't need to ground the new lights to the battery. That may be adding lots of unnecessary wiring (with the associated voltage drop). Any good ground to chassis near the lights should work as good or better. Make sure you fuse the new power wire from the battery. Or better yet, find a spare slot in the factory fuse box.

 

[highfructose]

The way to do this and keep the DRL function is to power the coil of the new relay off the low beam power, and to tap into the switched ground that activates the high beam relay for the other side of the new relay's coil. This way the auxiliary high beams will only come on when both low and high beams are on. During the day, the low beams are off, so the aux. high beams won't turn on, even if the DRL are on. A manual switch in series with the coil's ground on the new relay will allow you to enable or disable the auxiliary high beams so they don't necessarilly run all the time the high beams are on.

You don't need to ground the new lights to the battery. That may be adding lots of unnecessary wiring (with the associated voltage drop). Any good ground to chassis near the lights should work as good or better. Make sure you fuse the new power wire from the battery. Or better yet, find a spare slot in the factory fuse box.

That makes sense. Smart way to do it.

 

[LXinOBX]

The way to do this and keep the DRL function is to power the coil of the new relay off the low beam power, and to tap into the switched ground that activates the high beam relay for the other side of the new relay's coil. This way the auxiliary high beams will only come on when both low and high beams are on. During the day, the low beams are off, so the aux. high beams won't turn on, even if the DRL are on. A manual switch in series with the coil's ground on the new relay will allow you to enable or disable the auxiliary high beams so they don't necessarilly run all the time the high beams are on.

You don't need to ground the new lights to the battery. That may be adding lots of unnecessary wiring (with the associated voltage drop). Any good ground to chassis near the lights should work as good or better. Make sure you fuse the new power wire from the battery. Or better yet, find a spare slot in the factory fuse box.

Interesting, thank you - worth noting that this is a solution that allows for the DRLs to "remain" operational

Again, many thanks

 

[Moby]

Are the DRL lights different in an LC (2020) versus the 570? I did this same set up but powered the coil for the relay for the aux beams directly off of the high beam fuse in the engine bay fuse block (this fuse is only hot with the high beam switch on in my LC). Put a switch inline so that the aux lights can only come on if the high beams are powered and the switch is in the on position. The power for the aux lights is directly from the battery (fused) to the relay and out to the lights.

 

[LXinOBX]

Are the DRL lights different in an LC (2020) versus the 570? I did this same set up but powered the coil for the relay for the aux beams directly off of the high beam fuse in the engine bay fuse block (this fuse is only hot with the high beam switch on in my LC). Put a switch inline so that the aux lights can only come on if the high beams are powered and the switch is in the on position. The power for the aux lights is directly from the battery (fused) to the relay and out to the lights.

I "think" the 2010 LC/LXs must configure DRLs differently vs your 2020. In the case of my '10 LX the hi beam fuse (#55 being one side) flows current for BOTH the DRLs and Hi Beams, not JUST the high beams. I am prob mis speaking but I think the whole "can bus" thisng comes into play with later model trucks