Spotlight Wiring Question

I am looking to wire in approx 200W of spotlights. I have the front fog switch installed within the cab and was hoping to utilise this.

I have done the math and 200w at 12v gives 16amps, so I need to pick appropriate cable sizes for that.

Following the below diagram, it shows the positive supply from the lamps coming back to pin 5 of the switch. Does this need to be cable sized for the lamps wattage all the way back to the switch and to the relay? Or can I splice a smaller cable back to the switch on the basis it only needs the supply to light the orange LED in it? My assumption was it would be the 25amp cable back to the relay but not necessarily the switch.

Thanks

That wiring diagram doesnt look right to me, give me a min to try and borrow one from the internet

Well here's one that looks like it was done by the same person as the one you posted

Assuming the switch pins are ID'd correctly here then this is the way to do it. You would only need to use larger cable off relay terminals 30 & 87 (and probably the earth too) as the other wires only switch the relay

Thanks Kev.

Has that switch not had it’s pin 4 and 5 reversed? I was using the diagram from here: https://www.firstfour.co.uk/defender-puma-fog-driving-light-switch.html

Just spotted that is based on the heated seat switch rather than front dogs, guess the pins are slightly different - not sure if I read if the operation is too, the fog switch isn’t just a standard on/off I don’t think?

OK have been scratching my head and looking at it. I think the diagram you posted first would work, it's just a different way of doing the same thing. I'll try explain the differences best I can, I'll call the one you posted (a) and the one I posted (b).

Relay terminal 86 is the one that tells the relay to switch the spotlights on. (a) does it via the high beam warning lamp and the switch being on making the circuit across 86 & 85. (b) does it by the switch being on which is fed from a main beam, 85 is already earth so circuit complete.

The reason the other wiring differs is for the LEDs on the switch. On (a) the amber LED for spots on is lit by the same feed as the lamps. With (b) the LED is lit by the switch being on when main beam is on.

In simple terms (a) the switch works on the earth of the relay , and (b) the switch works on the positive switching feed to the relay.

Hope this helps, I've been thinking and typing at the same time so it's not as coherent as it could be. I have always wired up like the image I posted which is why I thought yours looked wrong. In practical terms to only differences are where you get the main beam feed from, either the wiring to the bulb or from the dash warning lamp

Why would you fit spot lamps to a fog lamp switch? When you switch on your fog lamps its good bye visibility and oncoming traffic wont be pleased either..

I have been eyeballing these, says they fit Land Rovers, https://www.ebay.co.uk/itm/Car-IVA-...e=STRK:MEBIDX:IT&_trksid=p2060353.m1438.l2649

nobber said:

Why would you fit spot lamps to a fog lamp switch? When you switch on your fog lamps its good bye visibility and oncoming traffic wont be pleased either..

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Because I currently have an unused switch - it’s the auxiliary lighting one maybe is a better name rather than fog lights. Previous owner removed any additional lights, I would be looking to utilise that switch, wiring in as above so they came on only when the main beam was on. This seems to be how the wiring has been left in the car as when I hit the switch with main beam on I can hear the relay.

TeddyBS said:

Because I currently have an unused switch - it’s the auxiliary lighting one maybe is a better name rather than fog lights. Previous owner removed any additional lights, I would be looking to utilise that switch, wiring in as above so they came on only when the main beam was on. This seems to be how the wiring has been left in the car as when I hit the switch with main beam on I can hear the relay.

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If that is the case, and there is already a relay and switch wired up, then all you need to do is get a fused battery live to the relay, and then out to your lights. You would need to make sure the wiring is capable of carrying the loads you intend to put on it, and remember that a fuse is there to protect the cable, not the user or end product.

mick 1986 said:

If that is the case, and there is already a relay and switch wired up, then all you need to do is get a fused battery live to the relay, and then out to your lights. You would need to make sure the wiring is capable of carrying the loads you intend to put on it, and remember that a fuse is there to protect the cable, not the user or end product.

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That is exactly what I am hoping, I plan to test the relay this weekend - figured if I hook a multimeter up to it and press the switch I should be able to see if it already has a fused supply

TeddyBS said:

That is exactly what I am hoping, I plan to test the relay this weekend - figured if I hook a multimeter up to it and press the switch I should be able to see if it already has a fused supply

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If you just test the output for voltage, all you will find is if it has a supply or not, pretty pointless in the grand scheme of things. You need to know the CSA of the cable going to the relay, and if it’s fused. The only real way of doing that is to trace the cable all the way back from the relay to wherever it’s connected.

Yeh I meant more if it is all adequately connected in to the switch etc. The relay is in the battery compartment so fairly sure it should be easy to trace back t source

So... been having a play about tonight and after quite a faff I located the correct relay (it was hidden under the subwoofer in the battery compartment...) I have also replaced the in line fuse as that had blown. And now everything seems to work... the little orange led comes on when the button is pressed, perfect, there is just one problem in that the previous owner removed the lights and I have no idea where the wire was cut.

So I was thinking I would probably run new wires from the relay (which is rated to 40amps) as the wires currently look awfully thin. However the wires go out the inboard side of the battery compartment and into the Center of the wagon, I assume to then run up into the dash or out to where the lights were. Is there anyway easily of accessing these to try and work out where they previously went? I can’t work out whether the hole was created in the battery compartment for this reason... I am reluctant to just leave the old wires lurking in there. I can work out which ones go to the switch, it’s just the ones that fed the lights.

TeddyBS said:

So... been having a play about tonight and after quite a faff I located the correct relay (it was hidden under the subwoofer in the battery compartment...) I have also replaced the in line fuse as that had blown. And now everything seems to work... the little orange led comes on when the button is pressed, perfect, there is just one problem in that the previous owner removed the lights and I have no idea where the wire was cut.

So I was thinking I would probably run new wires from the relay (which is rated to 40amps) as the wires currently look awfully thin. However the wires go out the inboard side of the battery compartment and into the Center of the wagon, I assume to then run up into the dash or out to where the lights were. Is there anyway easily of accessing these to try and work out where they previously went? I can’t work out whether the hole was created in the battery compartment for this reason... I am reluctant to just leave the old wires lurking in there. I can work out which ones go to the switch, it’s just the ones that fed the lights.

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No idea at all about spotlights, I have never felt the need.

But I can tell you why the hole in the battery compartment is there. It is to allow ventilation, so that explosive hydrogen gas from the battery doesn't build up in the compartment.

Hmm well if that’s that hole it’s a bit odd as it seems it was attempted to be sealed up with the wires that were previously going through it

TeddyBS said:

Hmm well if that’s that hole it’s a bit odd as it seems it was attempted to be sealed up with the wires that were previously going through it

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Not uncommon, these are old vehicles, and have often been cut around a lot by previous owners.

Interestingly I am doing a piece of work in my job at the moment about the hydrogen created by submarine batteries. I reckon my colleagues would have a field day if they saw the state of my battery compartment haha

TeddyBS said:

Interestingly I am doing a piece of work in my job at the moment about the hydrogen created by submarine batteries. I reckon my colleagues would have a field day if they saw the state of my battery compartment haha

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People are pretty complacent about it. But not usually those who have seen a battery explode.
I would try and leave the hole, or several holes, open on the finished job, and nothing in there that is likely to create any sparks.

That is, believe it or not, the genuine LR wiring for Aux lighting (2x 55w on main beam trigger) when chosen as an accessory - can be factory or dealer fit. (Or DIY if you pay a fortune for the kit).

The relay appears to have been part undone (should look like a normal relay) as it should be fixed to the inside of the battery box.

Wiring your looking for runs on the passenger side chassis rail and up the transmission tunnel, splitting behind the Heater box (where the wires head through the bulkhead into the centre console) and then should be along the inner wing top in plastic trunking - finally appearing at the top of the Rad by the intercooler/ top hose before splitting out for a feed to each light (clipped along the radiator frame down each side)

Have fun