Led bar, switches and harnesses

Landy_Ben said:

Hi.
I currently have a boomslang loom on my 300tdi.

I want to put a led bar on the roof and have seen a ready made loom that has relay, fuse etc and gets switch for full beam from the headlight plug and like the boomslang gives a new plug for headlamp.

I am assuming it’s not recommended to use both at same time? What about if led bar is plugged into RHS only.

finally if I wanted the light bar controlled by a switch and then the full beam switch (ie can choose not to have it on) I assume I wire the switch in the headlamp feed.
Thanks

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1. 12v fused from battery To relay.
2. Trigger wire from reversing lights or headlights main beam to relay
3. Ground from relay to suitable ground
4. Feed of 12v to lights from relay
5. Ground from lights to suitable ground

Landy_Ben said:

Hi thanks for the help so far. Been doing some reading off older posts and the hilux spotlight wiring page that gets referenced.

wiring front led bar and rear work lights (separately)

I think what I need for each is

1. 12v fused from battery To relay.
2. Trigger wire from reversing lights or headlights main beam to relay
3. Ground from relay to suitable ground
4. Feed of 12v to lights from relay
5. Ground from lights to suitable ground

I want to be able to switch rear work lights on without putting in gear so I assume I need another trigger 12v feed to relay with a switch in so when on it turns on lights without being in reverse.

I want to be able to turn led bar off when main beams are on sometimes. So I assume in this case the switch is in the ground from relay


Does that sound right?
Am I over complicating it by wanting to turn led bar off? I may never want to turn it off.

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Landy_Ben said:

Hi thanks for the help so far. Been doing some reading off older posts and the hilux spotlight wiring page that gets referenced.

wiring front led bar and rear work lights (separately)

I think what I need for each is

1. 12v fused from battery To relay.
2. Trigger wire from reversing lights or headlights main beam to relay
3. Ground from relay to suitable ground
4. Feed of 12v to lights from relay
5. Ground from lights to suitable ground

I want to be able to switch rear work lights on without putting in gear so I assume I need another trigger 12v feed to relay with a switch in so when on it turns on lights without being in reverse.

I want to be able to turn led bar off when main beams are on sometimes. So I assume in this case the switch is in the ground from relay


Does that sound right?
Am I over complicating it by wanting to turn led bar off? I may never want to turn it off.

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gymmaniac said:

considering MOTs shouldn't any auxiliary lights be on a separate switch and not come on with main beam?

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mick 1986 said:

Personally, I don’t like earth switching. If you get a short to earth, before the switch, the switch becomes useless.

Start with the reverse circuit. If you want to switch the lights on from two sources, I would use a 5 pin changeover relay. The relay has a normally closed state, and a switched state. So the reverse light feed goes to the normally closed side of the relay, the reverse lights will power the rear LEDs. If you want to turn them on manually, switch the switch and the relay changes state to a battery live, and the lights come on. The reverse light won’t come on as the relay is effectively open to that circuit. You could also use a standard relay, but that will mean using diodes to stop current flowing “in the wrong direction” through the circuit.

If you want to be able to use main beam without the spot lights, just place the switch is the feed line from the main beam. With main beam off, the spots are off. Switch main beam on, and the new switch off, spot lights off. Main beam on, new switch on, spots on.

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mick 1986 said:

No. Any “auxiliary” lights should extinguish with main beam being turned off. It’s in the vehicle lighting regs.

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mick 1986 said:

Personally, I don’t like earth switching. If you get a short to earth, before the switch, the switch becomes useless.

Start with the reverse circuit. If you want to switch the lights on from two sources, I would use a 5 pin changeover relay. The relay has a normally closed state, and a switched state. So the reverse light feed goes to the normally closed side of the relay, the reverse lights will power the rear LEDs. If you want to turn them on manually, switch the switch and the relay changes state to a battery live, and the lights come on. The reverse light won’t come on as the relay is effectively open to that circuit. You could also use a standard relay, but that will mean using diodes to stop current flowing “in the wrong direction” through the circuit.

If you want to be able to use main beam without the spot lights, just place the switch is the feed line from the main beam. With main beam off, the spots are off. Switch main beam on, and the new switch off, spot lights off. Main beam on, new switch on, spots on.

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Landy_Ben said:

So with this relay am I right in thinking 30 goes to the lights87a to reversing light, 87 to switch what. Is connected to 86 and 85? Thanks
View attachment 220907

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mick 1986 said:

No. 85 and 86 are the coil, so this is what switches the relay “on or off” (actually closed and open). If you want to use this relay in the reverse light circuit, then you would wire it like this:
85 to earth or reverse light feed
86 to reverse light feed or earth (opposite of 85)
30 to battery pos via suitable fuse
87 to the rear work lights.

If you want to use this with a second feed to turn them on via a switch, then you need to use a diode on the reverse light feed, and put a second feed to the same connector, also with a diode.

Edit: After reading back through my posts, now I understand why you linked to that relay. yes you can use that relay in the way you describe, but not using the contacts as you have wrote.

85 and 86 would need to be wired to your switch (the one which would turn on the aux lights without reverse) and an earth. This would cause the relay to switch over from open to closed, so from 87a to 87.
87 would be connected to battery pos via a suitable fuse.
87a would be connected to the reverse light feed.
30 would be connected to the rear aux lights.

The only problem I can see is that the LEDs may be too high a current draw for the standard reverse circuit, but you could speck LEDs that aren’t too high a current and it would work fine.

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Landy_Ben said:

Mick thank you very much. Useful to be able to learn and ask questions. Ben

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mick 1986 said:

No problem. Make sure you check the rating of the lights, and ask questions if your not entirely sure what you are doing. It’s better to ask what seems like a stupid question, than it is to set fire to the vehicle because something was wired up wrong.

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Landy_Ben said:

So in this scenario

85 and 86 would need to be wired to your switch (the one which would turn on the aux lights without reverse) and an earth. This would cause the relay to switch over from open to closed, so from 87a to 87.
87 would be connected to battery pos via a suitable fuse.
87a would be connected to the reverse lightfeed.
30 would be connected to the rear auxlights.


I need power switched by the switch to energise the relay to switch is that right?

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mick 1986 said:

Yeah, that all sounds right to me. Check the actual relay you buy, just in case the terminals are wired up differently, but for the relay in the photo, yes that is correct.

Edit: what rating are the lights you are trying to use as aux lights?

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Landy_Ben said:

Hi at the front it is a 300w 50” led lightbar.

At the back it is 2x 27w led lights

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