[Che]

I just bought an SPST LED switch for my spotties to replace the rusting switch dangling from behind my dash. I had the new switch wired up and looking neato on the dash, but for some reason the new switch has its own set of operational rules - everything turns on just fine (so too the LED), but the spotties won't turn off when you flick the switch back. The only way to turn them off is to kill the headlights completely... like a hard 'reset'.

The switch is wired correctly, and the multimeter is indicating it's working perfectly fine. The only difference between the two switches is an LED indicator, so am I right in thinking something about the LED is nulling the ability to trip the relay back to 'off'? Can anyone explain what's going on?

[SierraDan]

I assume by "wired correctly" you mean to suit negative switching.

But it sounds like what happened to me when i didnt set it up for negative switching.

[Che]

Shit that didn't even occur to me. There's three pins - in, out, and LED. Or, the thru circuit and the LED. I've now tried every possible combination and the way I had it first seems to be most successful. Not sure what I need to do to maintain a correct negative switching circuit... hmmm... i'll look into it. I'll have to have a closer look at the relay feed too.

[Bugsta]

An LED is a diode. It will only work in one polarity. I would expect the LED connection to be a (-) negative/earth, with the switch switching (+) positive, hence giving the other side of the diode positive when ON.

What have you connected the 'LED' terminal to?

Sounds like the relay is finding an earth through the LED.

[Scrawny]

Leave the earth for the switch disconnected and retry

[royce]

the terminals are usually Supply, Accessory and Earth.

So power comes in on supply, when the switch is on power comes out on accessory (to your relay) and also supplies power to the LED which then completes the circuit via the earth terminal and lights up

So if you dont have power on the supply terminal (IE you are negative switching) then it wont work.

A work around;

Hook constant 12v up to the switch supply (fused with a low rating)
Run from accessory to pin 86 on the relay
Find the high beam trigger wire on the back of the headlight plug (should be the RH vertical pin looking from back, but check cause I cant remember right now) it will go earth when on high beam and nothing on low beam when the headlights are unplugged)
Run a wire from this to pin 85 on the relay, then continue this wire along to the earth pin on the switch.

Now youll have a relay switching circuit that completes with switch on and high beam Battery>switch>relay>headlight dip switch>earth and a LED light circuit Battery>switch>LED>headlight dip switch>earth

[christover1]

I had to remove the switches light on mine, to work on negative switch circuit.
(switch was on special, didn't want/need a light on it)
Other switches may have a better system.

[Reubs]

Use this wiring and your LED switches will work like mine!

http://www.auszookers.com/forum/download/file.php?id=23304&mode=view

[Reubs]

^^^ swap pin 85 and 86 if you are using the above diagram (although most relays are non-polarised so most wouldn't have a problem with not doing that).

[PurpleZOOK]

To simplify : power off the battery through your switch and back to the coil for the relay, one side will be 12v positive through the switch and one side to negative/earth (for the coil on the relay) then on the relay it will need a 12v positive off the battery to one side of the relay and the other to the 12v positive of the led bar (this is the normally open circuit being closed with the coil) the other wire on the led bar to negative/earth.

If it turns on with the switch but not off means you could have a faulty relay or the mech in your switch could be faulty. I'd put my money on faulty relay. Depending on how many amps your light draws will depend on the size of the relay you need( can determine this with a clamp meter), I personally don't use one on my bar because my switch can handle 10amps and the bar only draws 1.4amps. Relays are just used to carry the amps through it instead of the switch.

[fordem]

Are you sure that 1.4A draw is correct? That would be about 18W - would have to be a pretty small bar - 5~6 LEDs. Most clamp meters will only measure AC current - you need a DC clamp (with a hall effect sensor) to measure DC current - so that could account for an incorrect reading, an AC clamp might measure ripple resulting from an LED bar's switch mode current regulator.

There are two reasons to use relays - current capacity is one - voltage drop is the other. If you position the relay to minimize the length of the wires carrying the current, you can reduce the voltage drop in the cable - although this is less of a problem with properly designed LED lights than it is with halogen lamps.

[PurpleZOOK]

fordem wrote:

Are you sure that 1.4A draw is correct? That would be about 18W - would have to be a pretty small bar - 5~6 LEDs. Most clamp meters will only measure AC current - you need a DC clamp (with a hall effect sensor) to measure DC current - so that could account for an incorrect reading, an AC clamp might measure ripple resulting from an LED bar's switch mode current regulator.

Thats correct just depends on what your running/situation.