Lightbar Wiring to On/Off/On Switch

[Henrik]

I have this exact solution on my Qashqai, but I'm at McDonalds with my son who is all over the place at the moment, can upload some pictures later on how I solved it, if necessary?? (I haven't read all comments thoroughly, so don't know if needed). But I only used 1 relay.

Here's what I did:

I have attached 2 schematics of the wiring. One is of the wiring from the supplier (Sunyee). On the schematics, which are on Danish, it's the one with the word "leverandøren" on it.

To modify it to fit the other schematics with the on-off-on switch you have to modify it at the relay and at the switch that came with.

At the switch you cut it off so you have 3 lose wires. My switch have 3 pins. You then put the wires on as follows: 87 in one end, 85 in the middle, and 86 in the other end.

At the relay you cut the wire going from 86 to the switch and set it to the high beams.

And then you're done

 

[karlos_1984]

Hey guys, thanks for your advice. I haven't bought the switch as yet, but I've looked at the diagram posted above and Tony's advice and I've re-drawn it to see if I'm on the right track.
Can you guys take a look and see if this would work? Does the switch get ground via pin 85 to 86 on the relay in this method or should it be grounded inside the cab somehow? Again apologies for my lack of brains with this stuff. Thanks.

 

[bods]

That looks good to me. The switch will only need a ground if it is like the one shown earlier in the thread. If it is just a basic metal toggle switch it won't have a light inside, so won't need a ground. But either way will work and yes pin 85 on the relay is ground.

 

[Old.Tony]

Agreed. I'll add that you don't NEED to draw positive power from pin 30 into the switch. Because the relay coil draws such a small load, you could use ANY positive source inside the cabin and you won't affect anything nor overload it. Reduces the number of wires that you have to run.

You can't do this because of how you want the lights to work, but I usually prefer to earth-switch into the engine bay for two reasons: first, there's plenty of earth points available inside so I don't have to run another wire inside, and second if the cables catch/snag/get damaged they won't cause a fire because they're already earth-based. At worst, your lightbar comes on - and if your high beam is off, that won't happen.

 

[karlos_1984]

Thanks guys. So if I use switch p/n 63041BL on the narva page:
http://www.narva.com.au/products/browse/heavy-duty-3
I won't need to ground it? Tony would u suggest getting positive power for the top pin (constant) from something like splicing into the positive off the cigarette lighter socket and just running the high beam wire out thru the firewall?

 

[bods]

That's correct with the switch. If your wiring loom that came with the light bar is pre wired, I'd just use that. Saves having to pull the dash apart and at the end of the day it will do the same job... if you are concerned about having it rub through and earth out, then just cut that wire off at the relay base and just use it inside the cab. You can leave the other wire that already goes to pin 85 on the relay there and just connect the switch to that.

 

[Old.Tony]

I'd have the relay in the engine bay. You're only running one wire out to it, and one in from the high beam. The current in the switch and to pins 85/86 is really low, so you can provide the ultimate protection with a couple of 0.5A fuses.

High beam wire -> 0.5A fuse -> long cable into the cabin to the bottom pin of the switch a drawn in your diagram. This way if that wire is ever damaged it won't take out your high beam. Be aware that if your driving lights fail to come on, this new fuse (being another connection) would be a possible failure point.

Ciggy lighter -> 0.5A fuse -> top pin of the switch in your diagram. This fuse is also a potential failure point so don't mount it somewhere difficult to get to.

Why only a 0.5A fuse? The coils will use somewhere around 0.05A (50mA). 0.5A is 10 times that - so the fuse will never overheat from the current draw of the relay - but it's so, so light that if something did go wrong with the wiring the fuse would die extremely quickly, reducing the risk of fire (from your wiring) to zero.

 

[karlos_1984]

So I had a go at wiring the light bar up last night, as per my previous diagram. Ran the cable into the cab and tested with my portable battery and a test light and it was all good. So I went ahead and finished installing the rest, high beam splice and connected to main battery back into the ute, but I have no power to the light bar at all, either on its own or with high beam on. It's earthed to the negative battery cable bolt that's beside the battery tray. Any thoughts on what to look for? Test light on the positive battery connection shows its working, but I don't hear the relay switching at all. Seems strange it worked during testing with a portable battery box but not my main battery.

 

[Old.Tony]

Does the relay activate? If yes, check that pin 30 is getting power and the light bar is connected to a good earth.

If the relay does NOT activate, check that pin 86 is properly earthed (try connecting it directly to the battery negative for the test). Test that pin 85 is getting power.

If pin 86 is earthed and pin 85 is getting power and the relay isn't clicking, maybe the relay is faulty.

 

[bods]

^^ I would double check your wiring, as mentioned above. In your diagram you have pin 85 as the switching input and pin 86 as earth. Some relays have a diode in them, so power will only flow one way. Normally this means pin 85 should be earth and pin 86 should be your 12v trigger input.

 

[Old.Tony]

^^ I have one of these relays in my car now (80A) feeding power to the Anderson plug for my caravan. Easy to see if the relay has power - the diode lights up. I'll admit I would like to have an in-cabin indication of my outgoing power to tub and trailer but that's a project for another time.

For those interested, here's how I'd do it (very simple): I'd tap into the relay's output and immediately install a 0.5A fuse, then a small single wire heading into the cabin. In cabin, I'd use an appropriate resistor with a small green LED (so that the brightness of the LED wasn't too distracting at night) and then connect the other side to earth under the dash. If I was completely anal about it, I could feed the incoming power to pin 85 of a small 5-pole relay instead. Pin 86 to earth with both LEDs. Pin 30 to positive source (ignition-on only, there are several sources behind the dash). Pin 87 to a green LED and pin 87A to a red LED (both with appropriate resistors). When the trailer power is active the green LED lights up, otherwise the red one lights up.

 

[karlos_1984]

Thanks guys. Did some wire tracing with the test light, turned out to be a dodgy join between the in line fuse and the relay pin 30. Obviously my crimp/soldering needs some more practice. Funny how you always overlook the simple things when you're finishing up a job like this at 2am. All up and running now, was a simple fix.
Thanks for your advice and help. My next project will either be some reversing lights with a similar type of switch setup, or wiring a ctek or redarc charger to the tub. Glad I sorted this myself and learned a few things from you guys, cheers.

 

[bods]

Nice job. At least it was something simple lol.

I have a similar setup in my tub Tony. Only difference is I am only using a 60a relay with 6mm cable running to a 50a anderson plug mounted above the trailer socket for when we eventually get a camper trailer haha. I have a carling rip off switch in the cab to turn the relay on, although some sort of led feedback circuit from the output of the relay would be good to have in the cab to know it is working.

 

[Old.Tony]

My biggest problem is getting spade connectors large enough to fit the cable I'm using (8Ga). At the moment I'm taking one of the 8Ga's internal windings out in the exposed section of wire and it's fitting - there's still more than enough cable to handle the current I'm exposing it to (around 40A peak, 20A average). I've actually got two pairs of 8Ga cable (so 4 cables in total) running towards the back, with 2 of those entering the tub and powering the inverter which powers the fridge while driving.

Reversing lights would work very similarly to the high beam circuit (electrically identical in form, just a different feed). There is a reversing signal available in the cabin already, it will be in the wiring loom for the stereo (because head units need it to know when to switch to the rear camera view). This means you won't have to run a reverse cable all the way from the back into the cabin's switch and then back out again.