Thread: LED Light Bar - wiring harness

I've just installed my light bar on my D4...
Nice and easy... I wired the trigger relay into the front fog lights circuit...
Now I can switch the light bar on, only when the normal lights are on, I haven't had to fit an extra dash switch, plus the added benefit of a nice big light display on the dash, so I can't forget they are on..

OK I lose the front fogs use if it's foggy, but I can't remember the last time I ever used the front fogs, so not really a problem.

Originally Posted by Bluepippa

I've just installed my light bar on my D4...
Nice and easy... I wired the trigger relay into the front fog lights circuit...
Now I can switch the light bar on, only when the normal lights are on, I haven't had to fit an extra dash switch, plus the added benefit of a nice big light display on the dash, so I can't forget they are on..

OK I lose the front fogs use if it's foggy, but I can't remember the last time I ever used the front fogs, so not really a problem.

Unless I'm missing something, the way you have wired it is illegal.

On my D4, the fog lights will operate either with only the park lights on or with low beam on, or when the high beam is on.

If your LED bar is triggered by the fog light circuit and operates as above, it is illegal. Forward facing auxiliary lighting (driving lights / spot lights / LED bars) should ONLY be able to operate when high beam headlights are operating.

thanks for all the wiring suggestions,
but can you show how you have mounted the light bars?
I want to fit one to my d3, but this seems to be more difficult than on older cars.

Originally Posted by BMKal

Unless I'm missing something, the way you have wired it is illegal. .

Ok so what about adding another relay, using the high beam as a trigger to complete the light bar circuit...
In that way, I would need hi beam on and then use the front fogs as the switch for the light bar.. Without hi beam on I still have front fogs for when it's foggy !!!

My basic logic, but it could work.... Couldn't it

Can't see it working. If you have the fog lights on and then select high beam power is cut to the fog lights.

Originally Posted by rufusking

Can't see it working. If you have the fog lights on and then select high beam power is cut to the fog lights.

I thought that too .................... so went outside and checked on mine.

My fog lights stay on with parkers only, with low beam OR with high beam. They go out when you turn the headlight switch off.

Originally Posted by Bluepippa

Ok so what about adding another relay, using the high beam as a trigger to complete the light bar circuit...
In that way, I would need hi beam on and then use the front fogs as the switch for the light bar.. Without hi beam on I still have front fogs for when it's foggy !!!

My basic logic, but it could work.... Couldn't it

Would have to sit down and look at a wiring diagram to figure it out to be sure - but I think it would work. I'm sure there's a way that you could make it work.

The other problem that I see with this though, is that you have your fog lights running all the time (unless you choose to turn fog lights and LED lights off). On high beam - nobody is likely to notice this. But when you are on low beam and your fog lights are still on - many people object to this, and it is in fact also illegal. I have been pulled over by the coppers here in Kalgoorlie for driving a Playdo with both low beam and fog lights on (I didn't even realize that they were on). Fortunately, I got off with a warning.

To be honest, I'd be just running an independent wiring circuit for the LED lights, power source triggered from high beam, and with a dedicated switch inside the cabin. You don't need to drill any holes for a switch inside the cabin - there are "pendant" style switches available (eg. NARVA) which just stick onto the dash somewhere using double sided tape. Most people mount this type of switch somewhere just below the steering column.

At least this way - everything is legal and you won't have to go through the cost and inconvenience of re-wiring it all later on if you get busted.

I stand corrected! Even went out and checked. This could work.