Hello everyone, I’m new but I have been reading quite a few post on wiring a 12v led light on vehicles using fog light or high beam headlights and at the same time been able to manually switch them on. The issue is that all of those diagrams require a 3 pole switch. In my case I’m looking for something more technical. my truck has automatic high beams and 6 auxiliary switches, I want the led light bar to turn on with the high beams but only if I have auxiliary switch 1 turn on, but then I want auxiliary switch 2 to turn on the led light bar regardless of what is happening in switch 1. What I would like to make sure is that the automatic high beams circuit is safe and also that I’m not back feeding the circuits.
The specs of the light is 14Amps 182 watts.
only thing I can think of is doing 3 relay. One for the high beam, one for switch 1, and last one for switch 2. But again I’m not sure if that is ok or will it back feed and burn something?

 

In my case I’m looking for something more technical. my truck has automatic high beams and 6 auxiliary switches, I want the led light bar to turn on with the high beams but only if I have auxiliary switch 1 turn on, but then I want auxiliary switch 2 to turn on the led light bar regardless of what is happening in switch 1.

But you want the red light bar on only if the high beams are on also?

 

But you want the red light bar on only if the high beams are on also?

I would like the ability to choose. LED light bar on with the high beams or just on with one of the auxiliary switches

 

Your answer is not specific.
Does this do what you want?

EDIT:
The light bars will only work if the hi beams are on.
Either light bar will light independently from each other.

 

Your answer is not specific.
Does this do what you want?

EDIT:
The light bars will only work if the hi beams are on.
Either light bar will light independently from each other.

View attachment 337401

I only have one light bar. I want the light bar to turn on with the hi-beam in one setting only. then I want to turn it on with out the hi-beam. I did a drawing not even close to your but maybe you can see my idea on it lol

 

Your answer is not specific.
Does this do what you want?

EDIT:
The light bars will only work if the hi beams are on.
Either light bar will light independently from each other.

View attachment 337401

I believe in my drawing, I can turn just the light bar ON with switch one. then with switch two, I can control the light bar turning ON or OFF with the Hi-beam signal

 

I only have one light bar. I want the light bar to turn on with the hi-beam in one setting only.

What setting turns on the light bar?

then I want to turn it on with out the hi-beam. I did a drawing not even close to your but maybe you can see my idea on it lol

What setting(s) turn on the light bar without the hi beam?

 

I believe in my drawing, I can turn just the light bar ON with switch one. then with switch two, I can control the light bar turning ON or OFF with the Hi-beam signal

Oh...so the light bar can turn on initially with sw1 without the hi beams on, then if the hi beams turn on, control the light bar with sw2?

 

Like this:
If sw1 is closed and the relay turns on, there might be a slight "blink" of the light bar with sw2 closed.

 

I redrew your drawing from post #5.
I think it does what you want but what "safe" conditions did you want to consider?

 

I would do the "logic" and switching on the low current side to avoid high current switches,


SW1 - Master Enable Switch, when off, Light Bar Off period.
SW2 - when ON = Light Bar always ON, when OFF = Light Bar ON when Hi Beams ON.
The 1N4001 is a 50V reverse voltage and 1A constant current (30A surge) and should be good for your relay.
The JD1912 Car Relay (40A) requires 150ma for coil, much less than 1A capability of 1N4001 diode.

Operation:
If SW1 is ON and (HiBeams or SW2 is ON) then LightBar is ON

The function/sequence is slightly different than your original post. See next post for a different approach more closely matching what you wanted.

 

Now if you want your sequence, I think this will work per your requirements.

SW1 - Enables Hi-Beam to turn on Light Bar
SW2 - Will turn on Light Bar regardless of whether Hi-Beams are on or off.

The diodes work as a logical 'or' function.
The description of operation would be:
If "SW1 and HiBeams are ON" or if "SW2 is ON" then the LightBar is ON

 

Now if you want your sequence, I think this will work per your requirements.
View attachment 337416
SW1 - Enables Hi-Beam to turn on Light Bar
SW2 - Will turn on Light Bar regardless of whether Hi-Beams are on or off.

The diodes work as a logical 'or' function.
The description of operation would be:
If "SW1 and HiBeams are ON" or if "SW2 is ON" then the LightBar is ON

This is pretty much what I was looking for but I have one problem aux_sw1 is already pre wire on my truck from factory and has ignition power, I would need a way to that 12v ignition power to control hi beams signal. (A relay maybe?)

 

I redrew your drawing from post #5.
I think it does what you want but what "safe" conditions did you want to consider?

View attachment 337411

I’m afraid that somehow I could back feed 12v to a factory circuit like the hi beams? Maybe adding diode should help?

 

OK, so you have added the requirement that SW1 and SW2 have +12V on one terminal and that can't be re-wired.
So you add another low current relay (K2).

 

I’m afraid that somehow I could back feed 12v to a factory circuit like the hi beams? Maybe adding diode should help?

You could add diodes like this:


D1-D3 will suppress emf energy produced by the relay coils when they are energized, then de-energized. Sometimes this energy can induce disruptive energy into nearby electronics or wires causing erratic behavior. D4 will prevent the back feed.
I've shown SPDT relays, but they can SPST relays.

 

with the high beams but only if I have auxiliary switch 1 turn on, but then I want auxiliary switch 2 to turn on the led light bar regardless of what is happening in switch 1

aux_sw1 is already pre wire on my truck from factory and has ignition power

Okay, if S2 is not prewired to +12V, then the circuit below should work with one SPDT relay and no blocking diodes, but it does reverse the functions of S1 and S2, if that's okay:

 

Okay, if S2 is not prewired to +12V, then the circuit below should work with one SPDT relay and no blocking diodes, but it does reverse the functions of S1 and S2, if that's okay:

View attachment 337454

Be careful with this solution as the Light Bar requires 14A that you are adding to the High Beam circuit. Probably blow HB fuse.
And SW2 must be capable of 14A.

 

Be careful with this solution as the Light Bar requires 14A that you are adding to the High Beam circuit. Probably blow HB fuse.
And SW2 must be capable of 14A.

Okay, I missed that.
It's certainly something to be considered.

EDIT: Okay, here's the circuit with an isolation diode to allow both switches to control the relay, and thus the Light Bar current goes through only the relay.
A SPST relay can now be used if desired.
As before the S1 and S2 switch functions are reversed, but otherwise should work as you want, with S1 energizing the light whether S2 is on or off.

 

Okay, I missed that.
It's certainly something to be considered.

EDIT: Okay, here's the circuit with an isolation diode to allow both switches to control the relay, and thus the Light Bar current goes through only the relay.
A SPST relay can now be used if desired.
As before the S1 and S2 switch functions are reversed, but otherwise should work as you want, with S1 energizing the light whether S2 is on or off.

View attachment 337476

In this case the truck already has s1 and s2 prewire with 12v ignition