wiring light bar harness

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Wiring diagram for negatively switched headlights

[kenwahoo Junior Member Find all posts View Profile Close kenwahoo]

I've seen that Traxide negative switching diagram and been comparing it to their positive switching one. Only a few differences although they are important. If you have the nounce it won't be difficult to change one to the other. only thing is that I see the connection of high beam to common via switch with pins 85 & 86 but some setups have reversed the connections for 85 & 86 eg 86 to high beam rather than common. does it matter which way round it is?

Apart from that I'm now planning to upgrade the headlight loom at the same time, I just found Bushranger's instructions in wiring their spots. They provide a diagram for positive switching but include instructions to change to negative switching. Everything else is the same except for:

7. Connect the 2amp fused red wire (from switch) to constant positive (+) at headlamp using Quick Connect, and connect negative (-) black wire from the relay to negative (-) high beam switching wire on the headlamp. This wire may need to be extended. Insulate and protect connections with electrical tape.

They added a 2 amp fuse to the red wire from the switch. Is this necessary? Anyway, this seems easy enough to change the loom to a negative switching one. Useful for someone who's just doing the spotlight/light bar alone.

[kenwahoo Junior Member Find all posts View Profile Close kenwahoo]

I was busy upgrading the loom that came with the lightbar and just had an Eureka! moment with it as I have to reconfigure it for the negative switching aspect. Thought I may as well beef up the wires at the same time. Been reading about relays and looking at the different ways people have hooked up their lights. It finally dawned on me that we are looking at 2 separate circuits with respect to the relay in understanding why we do it a certain way. The lights are, in a way, no different to a hand held torch. Battery supplies the power and the plus and minus are interrupted by a switch to a globe wired inline. For the car, battery is the same and the torch globe is the spotties or light bar. The switch is the relay itself. Now, pin 30 on the relay is always power in from battery and pin 87 is power out. That leaves pins 85 & 86 which is a separate circuit. [What complicates circuit is the negative switching aspect. As I have mentioned above, I found this to mean that power is always on for the positive and the negative is used to switch on and off. So the whole thing becomes quite simple.] Pins 30 & 87 in the relay used is normally open so that no current flows between them. We need to close this circuit to provide power to the light bar or spots. This is done when the circuit with pins 85 & 86 is activated as the magnetic field created pulls pin 30 to close (contact) with pin 87. We put a switch in this circuit and hook it up to the high beam as this is required by law. The switch allows us to turn on the spots/lightbar only when we want it. So in a negative switching situation, pins 85 & 86 are connected to the high beam and the common wires on one of the headlight plug to provide the power for the relay to trigger the contact. When the high beam is turned on and we have our switch on, the relay is activated and that'll close the power to the spots/light bar. That's it basically. So it actually doesn't matter which way around pins 85 & 86 are connected to as it works either way.

Corigator, you've needed to include a diode between switch and pin 86. Perhaps this is not needed if you use pin 85 for the common and 86 for the high beam like Traxide. Anyway, you've done yours and as it works there's no need to do it except for the sake of discussion. Except that I don't quite get why Traxide taps battery positive to pin 85.

So apart from than Traxide's method, have I got my explanation right?

[mjrandom Out of control poster! Find all posts View Profile Close mjrandom]

A relay is just a high current electric switch. That is the best way of looking at it. You trigger the electric switch with a little manual one.

[kenwahoo Junior Member Find all posts View Profile Close kenwahoo]

On a practical note, how do you all tap into the high beam and common wires? I know of scotch lock and have used them. Others seem to use a H4 adaptor which seem to be a male plug with wires sticking out and adding additional wires to a female to plug back into the bulb. More costly but seems to be better method. What else is avail?

[kenwahoo Junior Member Find all posts View Profile Close kenwahoo]

Also need a ground point inside the cabin for the switch, what's the location of a convenient point? Save me the trouble of finding one. thanks

[Corigator Avid PP Poster! Find all posts View Profile Close Corigator]

On a practical note, how do you all tap into the high beam and common wires? I know of scotch lock and have used them. Others seem to use a H4 adaptor which seem to be a male plug with wires sticking out and adding additional wires to a female to plug back into the bulb. More costly but seems to be better method. What else is avail?

Just type H4 extension adapter into eBay. These make it easy to tap into the light power. I got a cheap $8 one, but had to upgrade the wiring to suit the headlight power requirements. (I just soldered in second wires on each one. Also tapped in the signal wires to the switch / solenoid directly behind the make end)

[BiLLz0r Advanced Member Find all posts View Profile Close BiLLz0r]

There's also this diagram from the Ironman Website.
https://dl.dropboxusercontent.com/u/...-switching.JPG

There seems a few different ways to do it. This diagram doesn't allow for a switch with an internal light though.

[kenwahoo Junior Member Find all posts View Profile Close kenwahoo]

Just saw a way to connect to headlight wires on an Amarok site. He cut off the crimping part of a terminal, stripped some insulation off the wire to be tapped and the end of the wire that needed to be joined, twisted them together and crimped the total twist. I like this method as it is crimping and you can then tape the whole lot. Looks very secure and won't have the disadvantages of solder and all the advantages of crimping. I think it's better than scotch lock. In actual fact, thinking about it further there's no need to cut the terminal to just use the crimping end. What you can do is to strip a bit of the wire you're tapping into and crimp the terminal to that. because you have a terminal you crimp a spade to your other wire and push into the terminal, voila. This way you can remove it if it doesn't suit.

[jaco150 Junior Member Find all posts View Profile Close jaco150]

I hope I can add a few thoughts to this discussion.

It always amazes me to see the WIRES that someone brags about when they open up the hood to show the newly installed device...
Time & Time again - the wire gauge is over-sized for the application, it looks great, but only a waste of money in my opinion - and sometimes even makes the install more difficult.

10AWG - is rated for 30Amp to 10m
- if you have a light-bar that draw 30 amp, you have bigger problems on your hands.
( 12 AWG is for 25 AMP @ 1.8 meter )

most light bars draw somewhere between 5 - 10 amp (some super sized-double row bars draw 15 amp)
- 12-14 gauge should cover 90% of all light bars without any problem.

see wire gauge chart for some good insights into where to spend the hard earned $$
http://assets.bluesea.com/files/reso...ence/20010.pdf

[kenwahoo Junior Member Find all posts View Profile Close kenwahoo]

Wow, first time anyone has taken me to task for spending too much. First off, was I bragging? I thought I was seeking advice from fellow forumers as to how to configure the loom I got. Sure in the end in reconfiguring it I've used thicker wires and perhaps have overengineered it, what's that to you? You reckon it's a waste of money, ok. Let's see I've used 10awg/6mm instead of 14awg/4mm. 6mm is under $3 and 4mm $1. I actually found 6mm for $2. Still, total length I've needed to get is 1.5metres x2 (red and black) so I've overspent $6!! Are you that short of money that $6 is going to make a difference. Barely buy a cup of coffee. I happen to be a pensioner and I don't feel that pinch so why are you so hot over it? I see that you own a Prado 150. If you got that new you will have spent more than $50k and if you have a Kakadu it'll be double that. Hey my Prado is 1996 and cost me less than a quarter of a new basic 150 as I got mine secondhand about 8 years ago. I've not felt the need to do any accessorising until now apart from a towbar and nudge bar. Just practical things. Now the light bar is rated at 300watts which is 25amp. Being a Chinese one it probably isn't driven to max but I don't know that. Don't have any instruments to measure what it chews so I have to take the rating as provided. Twin core 14awg is rated under 25amp so imo that's no good. The next size is 12awg and I got 10awg because they didnt have any 12awg on a per metre basis. If you want to take the risk and use thinner cable, by all means do so. It's your vehicle and if it goes up in smoke because of it that's your perogative. Just as it's mine to spend my money as how I wish and in this case I do so wish. Isn't it better to over engineer than under engineer. After all, aren't all our vehicles under engineered with respect to the wires. I know mine are as they are a skinny 2mm. Sure I lived with it since I got it but around metro, there really isn't the need to have better lights with all the streets being lit up. I'm happy to receive advice as that was the purpose I started this thread. Didn't know I was boasting about wires I hadn't yet bought or installed. By your attitude, Piranha ought not be selling any loom as theirs is 6mm and costs $250 for a negative switching one. That's less than half the cost of quality spotties or lightbar. If 14awg is sufficient, hey some of the chinese looms are advertised to be that and they cost just $20+. Quality maynt be the same as Piranha's or Arb's. I just find it amusing that you take me to task over less than $10 when you've actually spent thousands more in comparison. I suggest you look for someone else who's under engineered and is at risk of setting their vehicle on fire rather than criticise those of us who are happy to over engineer and spend our money as we please. Have a cup of coffee on me. Make it an Irish one with whiskey.

[jaco150 Junior Member Find all posts View Profile Close jaco150]

@kenwahoo - apologies if my post came over as a personal attack, was never the intent.
- I was referring to "in general", not to your install - and will have that coffee - with Jameson

The advice was specifically focussed around the AWG and appropriate sizing... thus why I added the reference.
With LEDs, the Wattage vs. Voltage calculation is not 100% the same as with halogen and very much depends on the LED type/quality, etc. and makes the guess of wire gauge even more interesting.
- the LED produces eg. 10W power, but only draws approx 4-6W.
- the LEDs are marketed mostly at WATT power output, not current draw.
I have looked at 250 - 300W bars that only draw 18-20amps

Apologies for making you want to reach out and strangle my IP address

[kenwahoo Junior Member Find all posts View Profile Close kenwahoo]

No probs. I'll go have an Irish coffee myself.

[Corigator Avid PP Poster! Find all posts View Profile Close Corigator]

- the LED produces eg. 10W power, but only draws approx 4-6W.
- the LEDs are marketed mostly at WATT power output, not current draw.
I have looked at 250 - 300W bars that only draw 18-20amps

Apologies for making you want to reach out and strangle my IP address

If that's true then I think we're close to a perpetual motion machine.

[jaco150 Junior Member Find all posts View Profile Close jaco150]

If that's true then I think we're close to a perpetual motion machine.

Agreed - the "high spec" quality lightbars normally have a true WATT vs AMP reflection @ the given voltage rating.

I had a look at many cheaper "300W" lightbars, but the official amp rating behind them @ 12v was 15-20 amp.