Thread: Auxiliary Wiring Kit / Driving Lamp Kit circuits?

Thanks PaulMc0308 - this is all the information I could hope for, and more.

I have the auxiliary light switch & a design for a latching circuit using 2 DPDT relays - so I think I can replicate the behaviour of the factory kit (but with better reliability...). I prefer that, as I would rather the driving lights were deactivated when ignition / lights (I'm not sure which) go off, rather than having them come on with the high beams until the switch is off (I can be forgetful..).

Sorry for the late reply, but I've been away.

Cheers

Originally Posted by mfhall

I would like to copy the Land Rover designed installation if possible.

Originally Posted by mfhall

This way I'd be sure the right circuits/fuses were used

I sense a dichotomy.

You either want it to work properly or you want it the way Land Rover made it....

I should close the loop on my original question.

I did buy the genuine LR momentary switch. I then made up a (complex ...) circuit that toggled a relay which connected a line from the high beam switch to the main relay behind the RF headlight and to the switch LED. The main relay conventionally switches power from the battery to the driving lights.

One point that I don't think has been made is that electrical safety/protection means that the power should NEVER come straight from the battery. Evenwith a fused relay, there is no protection against the wire from the battery to the fuse chafing and shorting - which would result in the sort of nasty under bonnet smoke, heat and smell I noticed coming from a parked Lexus the other day (called the fire brigade and the car was still there hours later ...). I took my power from a 150A fusible link in the engine bay fuse box. That way a major short should be arrested before further damage.

Many thanks to PaulMc0308 for the switch diagrams - it was very hard to puzzle out with a multimeter.

What I have now is a genuine LR driving light switch that activates driving lights only when high beams are on, and needs to be re-activated after headlights have been dimmed or switched off. That way I won't accidentally flash people with the driving lights when I forget they're on and hit the high beams when a bit too close for the driving lights ... I believe that's the original Land Rover intent.

The circuitry is hardly genuine though ...

Hi mfhall, thats a good read but can I suggest you do not use globes bigger than 55w.

I do not know the size of the wiring already available but a 15 amp fuse is too small for globes with a wattage greater than 55w.

For instance, a set of 100w globes would draw between 14 and 16 amps, depending on the amount of voltage drop in the wiring to the driving lights.

Even at 14 amp, the minimum AVAILABLE fuse size is 20 amps for safe operation of a set of 100w globes and if your fit 130w globes, you need to protect them with a 30 amp fuse.

PLEASE BE AWARE, you can’t just change the size of the fuse with a higher current rated fuse unless the wiring can handle the higher currents.

If you are using 100w a set of globes with the 15 amp fuse, you will not blow the fuse straightaway but you will eventually melt the fuse.

Any fuse must be current rated at least 25% great than the maximum continuos current load being applied to it and the wiring must have a continuos current rate 40% greater then the fuse.

BTW, using a small fuse will also cause excessive voltage drop and will help to make your lights run duller.

And is there still remaining the potential to fry the headlight switching for a D2a in particular?
(I think the D2a was the one that Tim did not develop a headlight switch kit for and was a lot more difficult to suitably modify? - although it has been done on this forum).

Originally Posted by gavinwibrow

And is there still remaining the potential to fry the headlight switching for a D2a in particular?
(I think the D2a was the one that Tim did not develop a headlight switch kit for and was a lot more difficult to suitably modify? - although it has been done on this forum).

It's the same wiring through the switch on the D2a - after all it is a stopgap FACELIFTed D2 not at D3. .

The issue with the D2a's is the connector on the headlight units makes it difficult to do a simple plugin replacement harness. The D2's use a standard connector on main beam so much simpler to make a plug in kit.

Originally Posted by OffTrack

... The issue with the D2a's is the connector on the headlight units makes it difficult to do a simple plugin replacement harness.

It's quite easy to make a 'main beam' tap-off from the D2a's 9-way headlamp connector, using BMW components.

This doesn't involve cutting or splicing into the existing headlamp harness, but it does require the main beam terminal to be released from the 9-way connector.

It can be removed and the headlamp harness returned to 'factory' condition, leaving no trace.

I'll sort out some pictures and BMW part numbers and post the details here.


Paul.

1989 Arles Blue 2.5TD 110 Hardtop
1999 Epsom Green Discovery II 4.0 V8i 'XS'



.

This is a brilliant tutorial, I have managed to get all the bits and pieces to use the modified diagram, only thing left is to pick my spots, thank you.
Stuart