Illuminated Carling style switch wiring

[GunMentalGrey]

So I've been crawling around under the D40 to install and LED light bar, reverse camera and reversing lights while also installing a brake controller.

Bought some illuminated Carling style switches, two lights in each, one for dash light illuminations, one for indicator. Each has 4 pins, two for switching, the other two for the illumination bit. It's my first time using this style switch, chosen because they fit easily and I could get one with 'zombie lights' tag to impress the kids.

Is it possible to get them to illuminate properly when switching an earth? Testing so far hasn't got it working properly. I've used a switching earth for the reverse lights and led bar, thinking it would be easier, but it appears to be causing issues with the switches (the last bit of the job). Haven't tested the reverse camera where I'll be switching the 12v to override the reverse operation.

All thoughts appreciated.

 

[Old.Tony]

Illuminated switches usually assume you're positive-switching because "earth is on the chassis anyway".

You can still negative-switch with it, but it requires a relay (which also means you can NOT worry about the load of the items still, because all you're still doing is earth-switching via a relay. Here's how.

Find a positive source - who cares what it is - and call it "the input". Connect it to the correct pole of the switch. Connect the output of the switch to pin 85 of a relay. Connect the other pins of the switch up as needed so they light up properly.

Now connect pins 86 and 30 of the relay to the chassis and pin 87 to the wire heading back out to the engine bay. Easy!

 

[GunMentalGrey]

Rats. Wish I'd realised that first.

 

[bods]

The genuine Carling ones can be used to switch the earth, because they have incandescent globes in them. The new Chinese rip offs have leds in them and because they are a diode, they can't be powered in the other direction. I have 2 original Carling ones on the dash in my d22 with earth's switched for a light bar and spot lights, they are a lot hotter than the led ones, but still work correctly.

I'm not even sure if you can still get the original Carling ones anymore...

 

[glennm]

Forgive my ignorance but why choose one method over the other i.e. positive instead of negative switching?

 

[bods]

It depends on your preference really. My thinking behind it was to get away with not having to run a 12v wire through the firewall, if for whatever reason it rubbed through. With switching the earth, if the wire did happen to rub through, worst case would be the switch would no longer turn the accessory on and off via the Relay. The high beam switch would still work as normal and switch everything off.

Certain models of vehicle though have a factory negative switched system in them. They have permanent 12v fed to lights and switch the earth on and off to trigger the lights. These are obviously a lot easier to switch the earth to keep the system the same.

 

[Old.Tony]

Oh there are other tricks too.

I switch the earths on my relays for the safety reason bods described, but also to halve the number of wires. Because I'm only earthing the coil of a relay, I can do that from any point - and the mounting screws of the dash are perfect for this.

It really doesn't matter - electrically - if you switch the positive or the negative. Either way, you have to supply either positive or negative to one side of the relay coil, and the opposite to the other side.

In the 2006-2012 D40s (and possibly more, but I know these ones are) the high beam is always positive. This makes a very simple circuit: tap that high beam wire, attach it to pin 85 (pins 85 and 86 are the coil pins of a typical 12V automotive relay). You have no choice but to earth the other side, so you end up reducing the wiring and switching required by using an earth-switched relay.

In some cars, however, they now flip-flop the positive/negative on the H4 globe. If you look at the base of the H4 globe (with the glass pointing away at you) and turn the globe so you have pins at the 9 o'clock, 12 o'clock and 3 o'clock positions, the left pin is ground, the upper pin is low beam and the right hand pin is high beam. In some cars, the earth pin is positive in low beam, but on high beam it goes positive and the high beam negative - the light still works, because power passes through the tunsten coil in either direction. Ordinary LED globes won't work and I think that's probably the reason for the games.

However, you can still switch driving lights from them, it just requires TWO relays. Relay 1 connects pins 85 and 86 to the earth and high beam pins of the globe. Pin 30 of this connects to (who cares, for the sake of this exercise let's choose positive) and pin 87 to pin 85 of the second relay. Pin 86 of the second relay is connected to your earth-switching switch inside the cabin. Now, pin 30 to the battery, and pin 87 to the driving lights.

Electrics are so much fun!

 

[GunMentalGrey]

I switched the negative because I was getting the trigger from another positive (High beam or reverse light). I was able to use the 12v from the trigger light to activate the relay and then could just interrupt the earth for the relay trigger to disable it. Both sets of lights will only run when the other trigger light is on that way. i.e. Light bar only on when high beam is on. Reverse aux lights on only when in reverse gear.

In the case of the reverse lights the aux lights are using the same circuit as the existing lights so I didn't need to run extra power for them. Ive installed 2x12w LEDs and after I switch the std globes to led (7w I think) the entire circuit will draw less than the original incandescent globe (21w each).

Back to the switches, think I'm just going to run without the active illumination, I'll be able to see if the switches are on anyway, and the extra light will be a big giveaway.

 

[bods]

The only way to get around it, apart from using relays or a positive trigger, would be to bust the switches open and desolder the led and solder it back in the opposite way... It is a lot of work though and knowing the Chinese, you wouldn't get it apart in one piece anyway...

 

[glennm]

Thanks for all the info. I suspect my sons Adventra is set the latter way Tony mentioned and it was confusing the hell out of me. His only has 2 wires and are h9s. I think i will have to be more creative/complex with a solution. A drawing maybe Tony? Would be a lot easier if you lived down the road!

 

[bods]

Yep, pretty sure Holden's have been negatively switched since at least VT. I helped someone fit some spotties to a VT at some stage and had to wire it up to switch on the negative side. It isn't as difficult as it sounds.

Basically, you put your fused 12v input to pin 87, pin 85 you tap into the high beam trigger wire (negative), you can run this through a switch if you like, pin 30 is the output to the new lights, pin 86 you can either put a second wire into the positive feed for pin 87 or tap into another 12v wire anywhere else (it is only to trigger the relay, so won't have much load on it at all).

Hopefully that makes sense...

 

[Old.Tony]

H9 globes aren't used for a mixed high/low. They're driving lights, high beam only, DRLs etc. H4s have two separate filaments inside and are the commonly chosen globe for many passenger vehicles in Australia. Whether they're switched "ordinary" (common is always earth) or "funky" to prevent LED replacement, the function is still the same.

If the H9s are the only high beam globes in the car, then treat them just as you would the high beam circuit of the H4. Pin 85 goes to one side of the H9 globe, pin 86 to the other, job done on relay activation. Now just move the power to the light bar etc - pin 30 to a power source (with fuse, don't ever forget the fuse) and pin 87 to the bar.

Just a word on which pins go where. There are two types of relay available for automotive use - a 4-pin relay and a 5-pin. The 5 pin relay has an extra pin for supplying power from pin 30 while the relay is NOT active called "87a". I often wire these "backwards", using the 87/87a pins as power sources (eg alternator -> 87, solar -> 87a) with pin 30 going to a DC-DC charger. Connect pin 85 to an ignition-on positive source (anything, accessories will do) and 86 to ground. When the car is off, the relay is "closed", a circuit is made from pin 30 to 87a, so the solar panel feeds power to the DC-DC charger. When the ignition is turned on, the relay activates, the circuit from 87a to 30 is cut, and pin 87 (remember, the alternator) is now connected to pin 30 (the DC-DC charger) and so the car is supplying power for the charger, not the solar panel.

 

[glennm]

As always thanks for the guidance. will run it to ground (hehe) this weekend i hope.