Is wiring aux driving lights to hi beams not possible?

[mikebontoft]

excuse the terrible title but I've been trying to figure it out. I just installed my hellas for use as canyon driving lights to supplement my high beams. I'll likely never use them on their own.

I know they use power side switching, but Toyota uses ground side switching for the headlight. what bugs me is, is it done in the combination switch itself?

my first attempt I decided to hook up the aftermarket relay as a grounded switch. I took from the diagram that the R/G wire would become a ground when the high beam was on. nope. every wire is a ground when no lighting is on.

so I found the same wire when the harness was disconnected only had full system voltage when the high beams were on. of course when its plugged in the relay won't engage. I would have thought being before the filament it would engage the relay as they are in series. again, apparently not. I'm stuck. help. lol.

I'm not stupid with electrical but I'm stumped... am I just gonna have to end up taking a switch to the cabin? its a clean install so far, I'd hate to mess it up.

 

[Antman]

It's easy to accomplish this!

Using any standard relay:


Post #85 - tap into wire that is +12V when Hi Beams are on. The wire that directly powers the bulb, for instance.

Post #86 - Ground

Post #87 - Power wire for your Hella's

Post #30 - Fused wire directly to your battery positive terminal.


The "other wire" for your Hella lights will need to be grounded as well.

This will give you "Hella's on" whenever your Hi-beams are on.


Good luck!

 

[mikebontoft]

hmm thanks antman... that's actually how I have it wired now. only difference is 85 and 86 are opposite but that shouldn't matter.

with the headlight plug disconnected I get the relay to click. When its connected and the light is on, the relay won't engage. I am tapped into the wire that feeds power to the hi beams. it should work, its wired in series!

 

[mikebontoft]

evening bump.... no one else has had this trouble here?

 

[GonOvr]

check your grounds and connections, make sure you have a good battery to body and frame grounds.

 

[mikebontoft]

my relay ground is soldered to the negative battery terminal. all body and engine grounds are good. headlights and hi beams work but the relay doesn't get power when it should... unless I'm off for some reason. power should pass through the relay as well as the filament. I guess that's not it.

 

[GonOvr]

The highbeam power wire is just a signal source to fire up the relay. The battery power is used to fire up the fog lights. You may have a bad relay as well. try swapping it out with another one. If it does the same thing then its your wiring.

 

[mikebontoft]

right. pin 30 on the relay which gives power to one end of the switch inside is direct to battery positive. pin 86 which is the signal for the positive side of the relay is there on that high beam power wire.

with the plug at the headlight I've tapped into, my fog lights will come on on highs like they are supposed to. when its plugged in, then nothing works (except for the headlight. that works fine).

I must have my signal wire in the wrong place but it didn't think it would be. now that I think about it, in order for it to be in series I have to cut the power wire to the high beam, attach pin 86 to one side and pin 85 to the other. damn.

 

[KidVermicious]

now that I think about it, in order for it to be in series I have to cut the power wire to the high beam, attach pin 86 to one side and pin 85 to the other. damn.

Wait, what? I'm no electrician, but that doesn't make sense to me. If you do that, you're just switching the power to the high beams. Power from the battery on post 30, power to the lights on post 87, 85 to ground, and 86 is your switched signal (tap your high beam power wire). Least that's how I wired my auxiliary reverse lights.

Have you tested out the relay itself? Are you able to get power through it on the bench?

 

[mikebontoft]

that is exactly how I have it wired. I'm going to use a multimeter again and see what I can find, it should work.

85 and 86 are on the side of the coil within the relay that creates the magnetic field that sucks the switch over to allow 30 to provide power to 87.

In order to have it series I need to have both power and ground before the filament. the bulb gets the remaining power. the relay should draw so little amperage I shouldn't notice a difference in light output.

 

[mikebontoft]

and yes the relay does work. I've made the driving lights work on hi beams when wired up this way, but only with the headlight plug disconnected.

 

[GonOvr]

plug the head light in, turn high beams on and check voltage at the relay and where you spliced in. The power wire on the head light isnt grounded until after the filament, if you wired it up the way you are thinking the headlight or the relay wont work. The headlight bulb is basically a resistor. The relay wont even know there is a ground due to the resistance of the bulb. If that werent the case you would pop your headlight fuse because you would be shorting the headlight power straight to ground. You probably dont have enough voltage to ignite the relay. Try running the engine, while doing it to. It may send enough juice to the relay to fire it up.

 

[mikebontoft]

that was going to be my next step. glad we're on the same track I do appreciate the help .

I do have one concern though. power doesn't care what the load is, just that there's a resistance. think of wiring lights in series: you have two resistors and because of series, they will both be dim. the relay draws so little that the light shouldn't be any dimmer. since the high beam ground is switched with the combination switch, then it would make a full circuit.

in other words its just like wiring in an indicator lamp for high beams. except the lamp is a relay.

 

[mikebontoft]

resistance on the relay was more than I expected... not wiring in series.

not sure why it isn't working... probably just end up with a switch

 

[mikebontoft]

resistance on the relay was more than I expected... not wiring in series.

not sure why it isn't working... probably just end up with a switch

of course that's my luck... I try what I had the first time, what antman, kid and nate said and NOW it works. yes before you ask it is exactly the same way I had it before. must have ost a connection somewhere on first trial. not sure how.