High Beam Trigger for AUX lights

I have been working on adding a circuit to my 99 that will trigger some aux lights when the high beams are activated. I have done a lot of research into this and I have it working correctly, but I have a weird issue.

FYI I know that the headlights are negatively switched.

I have this circuit wired to a modified rear heater switch from a landcruiser. It has been modified so that there are 2 12v inputs and 1 12v output. I can switch from a constant 12v supply or the high beam supply.

When I set the switch to the high beam side, then activate the high beams, the light in the switch lights up and the high beam indicator comes on. If I turn the high beams back off and then back on, the high beam indicator will not come on. The high beams still work just fine.

I tapped into the high beam indicator wire coming out of the steering column (R-G). You can see the attached wiring diagram for the high beam circuit.

Does anyone have any insight as to why my high beam indicator will work the first time but then not again after that?

 

In Tacoma Hi beam indicator will not work if both bulbs have burned low beam filament. It may not work correctly only if you have HID or LED (driver connected to the bulb socket instead of bulb). So if you don't have HID or LED drivers there make sure low beam still work.

Also possible that your switch is shorting the indicator wire (R-G) to ground what will make turn also the low beam filament (that is no good).

 

Everything still functions correctly, the indicator just does not light, at least after the first "turn on". The cluster lights are LED but my headlights are halogen.

 

Are you sure the low beam does not go off, when you switch to high beam? Also you can measure the voltage on R-G wire when High beam is on - it should be close to12V. If it is not, then why keeping High beam on try to disconnect your LC switch and see if indicator light comes on. I suspect your switch or whatever is behind it makes a short R-G wire to ground.

 

Are you saying that the low beam filament is supposed to stay on when the high beam is on? I thought it was one or the other, not both at the same time.

You may be correct that the switch is shorting that wire to ground. I'll have to check tomorrow.

 

Look at the wiring diagram you posted. The indicator gets power through the low beam filaments. When the headlight switch is on low all the power goes directly to ground so the high beam indicator is off. When the switch is on high the circuit's only path to ground is through the high beam indicator so it lights up.

Anyway, what RysiuM was suggesting is that maybe the low beams are staying on but they're just drowned out by the high beams. Get out of the truck and verify that the low beams actually turn off when the high beams go on.

 

Zackly

 

for my aux lights I have my relay tapped into the low-beam wire in the engine bay, they will only work when the low beam is on. I would think it works the same for high beam?

any specific reason for using the wire in the column? don't want to mess with the firewall?

 

It is my understanding that the low beam AND high beam get power once the headlight switch is activated. The high beam comes on when the high beam switch connects that circuit to ground.

 

Yes. So when lights are off the head relay is not powered so it doesn't provide power to bulb's common. Because bulbs are not powered therefore regardless of Hi/Lo switch position bulbs are off and Hi indicator is off.
When lights are on then the head relay is powered so it provides power to bulb's common. Now Hi/Lo switch grounds either Lo beam or High Beam filament. Because the filament resistance is very low, not grounded filament will have 12V provided from bulb's common via filament's resistance. It is OK to tap into Hi or Lo this contact to get 12V indication as long as you tap with high resistance like relay coil for example.

The rule is you tap into opposite beam what you want have relay triggered on. Meaning if you want your relay to click when High beam is on, you connect the relay to Lo beam side and vice versa. This is exactly how Hi beam indicator works - the indicator bulb is connected between Lo beam and ground.

Now if instead of regular H4 (or H6054) you have HID or LED driver or high performance harness with relays, then the logic above will not work. You will have to figure out something else.

 

Thank you for helping me understand how the circuit works! It all makes sense now.

I will actually be installing retrofits in the near future so this may not actually matter, lol. I will probably just tap into the trigger wire for the high beam on the retrofit controller at that point. It will be the morimoto motocontrol box.

 

You are welcome. I love this truck's wiring. So simple to understand. My 5th gen 4Runner or 2015 Nissan Versa Note is completely different animal. Master Body ECU is controlling everything almost impossible to change behavior. I still haven't figure out how to wire my LED bar to work with and without Hi beam in 4Runner. I mean not by hacking into wires. I always aim to get OEM look and quality on my mods.

 

then by your explanation my aux lights should not work. I have my relay tapped into the low-beam wire. when I turn on the high beams, power to the relay is disconnected. if low beams are on, then aux lights work as intended.

 

These trucks aren't all ground switching. Some are positively switched.

 

I don't know about 2004. I saw in diagrams 2003 is ground switching, same as 95 and 96 and 99. I assumed all years share the same. I could be wrong.

Of course we are talking here about model without DRL. DRL is completely different animal.

 

I'm pretty sure if you look at the DRL EWD, it shows the headlights as being positively switched.

 

Yep, but then wire colors and diagram is completely different from presented by OP.

 

If you look back at my op, I was replying to frizzman as to why his aux lights might work in his trucks configuration despite the info you're providing.

 

Got it. This is what happens when we do not


and

 

So I checked the switch and it is providing an alternate route for the power when the high beam switch is on, causing the high beam indicator on the dash not to light.

I am still confused as to why both the high indicator on the added switch and the high beam indicator on the dash work for the first minute or so, and then they don't. When I first open the door and pull the high beam stalk back to flash the lights, both indicators work, high beams come on, and aux lights come on. I can do this multiple times with the same results. After about one minute, the indicator on the dash will not work, and it will not work again unless I let the truck sit for a while, even after completely disconnecting the switch. It seems like it is time based.