Wiring in Aux Light Bar with Bright light switch - Advice

[Beau]

I'm installing a Light bar and here's how I'd like it to work.

Master switch for the light inside the truck will switch light on/off, however it won't turn on unless high beams are on as well.

With switch turned off, high beams still function as normal and does not turn on light bar as well.

I have a complete wiring harness for the light so where do I add in the additional high beam light to work with everything?

 

[trdcorolla]

I'm a newb at car electrical but i'm imagining adding a relay to your switch and the high beam wire as a trigger.

 

[Ramathorn15]

I'm bored and feeling generous lol. Hopefully you can read my chicken scratch. I'm dealing with a thumb cast so writing is a challenge.

 

[Beau]

Thanks for that. I did some research and instead of using a second relay it looks like I can use a 3 way switch and have the 3rd position powered via the high beams. Question is, is there anywhere under the dash that I can tap into a positive high beam source? I think the switched side is negative so I'm stumped how to make this work. Unless I have the ground side of the switch positive and used the switched ground? But then I'll also need to find a constant AC ground for position 1.

 

[Beau]

 

[Ramathorn15]

View attachment 2404060

I would stick to double relays. They're cheap and won't require you to run high amperage through your switch or add a diode. Plus you can easily switch the high beam relay for - switching.

 

[Ramathorn15]

And just tap the high beam - wire where just before one of the bulbs.

 

[Beau]

@ramath0rn

What about this? I will use one relay. This relay will be triggered by either the positive or negative side of the high beam circuit. I will then put a switch inline on either the ground or positive side of the trigger wires? This is even simpler than above. Thoughts?

 

[Ayune]

The light bar relay coil can be simply be powered by the high beam power, and switched by the light bar switch. The added load of the coil is insignificant.

The light bar’s power is taken directly from the battery with its own fuse.

 

[Ayune]

@ramath0rn

What about this? I will use one relay. This relay will be triggered by either the positive or negative side of the high beam circuit. I will then put a switch inline on either the ground or positive side of the trigger wires? This is even simpler than above. Thoughts?

Exactly.

 

[Ramathorn15]

If I follow, that would work by you would need a diode to prevent the switch from turning on the high beams.

 

[Ramathorn15]

Also, assuming I'm following what you mean correctly, you would still be able to turn on the light bar even if the high beams are off.

 

[Ramathorn15]

Actually, yeah. This would work. The high beams are - switched, so the actual switch in the cab would switch the + side of the relay trigger.

 

[Ayune]

If I follow, that would work by you would need a diode to prevent the switch from turning on the high beams.

Power to the high beams is already switched by the truck and not available if the high beams are OFF. Moving the light bar switch would have no effect on either set of lights.

Also, assuming I'm following what you mean correctly, you would still be able to turn on the light bar even if the high beams are off.

Sounds like he wants the lightbar to only be available if the high beams are ON.

 

[Beau]

Yes, I don't care for the light bar to work independently, but would like it off occasionally if I just want to use my existing high beams only. I'll start on this tonight and let you know how things go. I'm assuming the best place to get these trigger wires for HB is at the lights themselves?

 

[Beau]

And I'll also be cutting the DRL wire under the drivers side dash to disable the DRL.

 

[Ayune]

According to the wiring diagram the red-with-white-stripe wire (passenger side) or the red-with-green-stripe wire (drivers side) are the power to the high beam bulbs. The white-with-black-stripe wires at both bulbs are grounded.

Why disable your DRLs?

 

[Ramathorn15]

And I'll also be cutting the DRL wire under the drivers side dash to disable the DRL.

You can disable in techstream

 

[Ramathorn15]

Also, assuming the high beams are - switched, this will work nicely. If the high beams are + switch, then your manual switch has to control the - side of the trigger. Most nice switches the LED "on" indicator won't work when - switching. Just an FYI