Relay/Add-A-Fuse/Diode Question.

On my 3rd gen 4Runner I’ve been having some trouble getting my lighting wired up without issue. My goal with this was to have everything wired up without any aux switches and for it to all to look and operate as factory.

Running 2 DD ss3 fogs, and 2 DD ss2 ditch lights.

First plan was to just grab an add a fuse from the main fuse box for the high beams for the ditches and one off the DRL for the fogs and backlight feature on the ditch light's. Once I had this wired up I was having issues with the ditch lights flickering even with the high beams off. Turns out the hi-beam circuit gets around 3v of power even when off.

Ended up rewiring it all with dedicated relays because I wanted to go with thicker gauge wire. Still having issues. The relay will buzz and flicker at 3v going to the trigger but then work as desired with the high beams on.

Im assuming the original design of these older headlights was to have that 3v to the high beams by design. Is there a way to put in a diode with a specific break over voltage in to trigger the relay? Don’t really want to add a separate switch.

 

Mini fuse block on the battery for power for both circuits, trigger wires coming from add a fuses, and then the respective relays, for reference.

 

What year is your 4runner? Part of the issue may be that it's a ground-switched headlamp circuit, not power switched, dependong on the model year

 

Thinking about it, that would explain some things. It’s a 2002.

 

Unsolicited advice, you absolutely want ditch lights to be on a separate switch. Ditch lights are not high beams.

Are there zero blanks in your dash? There are ways to wire in aux switches and have them look factory.

 

https://irate4x4.com/threads/how-to-activate-a-relay-with-ground-switched-circuit.391629/

Reading thru this I think explains it. Hi-beam at low voltage is used for DRL (which I can’t turn off)

 

They are SAE/DOT high beam lenses and aimed correctly. Easier to just call them ditches due to their location.

I agree with this logic tho for the case of it being normal aux lighting I.e lightbars and Offroad stuff.

I’ve found it safer to do the auxiliary high beams off the oem stalk as they are easier to quickly turn off for oncoming traffic down the road.

 

On my ‘02 Tundra there is a connector which disables DRL when disconnected. But that model has DRL on the low beam at full voltage vs high beam at half voltage like you’re saying you see.

for newer T4R, I’ve used a relay off the low beam to “wash” the combined DRL / high beam signal to only pass clean high beam through to the 2021+ headlights for the shutter lead to the led projector. However, I assume when high beams are on, low beams are off, assuming H4 bulbs on your vehicle. The ground switched part wouldn’t really be a problem, you’d be washing ground to the final relay rather than power.
You might be able to leverage the parking light signal to do the washing.

so, new relay, 86 to parking light +, 85 to parking light ground, 30 from DRL + high beam and 87 is your high beam trigger to the relay running aux lighting.