Hi all,
I have been asked by a few people now what is the best way to wire up spotlights, so I am going to make a little guide below on how to wire up your spot lights. Please note that if you are fitting 4 spotlights you MUST wire them using 2 relays and 2 live feeds, as one relay will not be able to cope with the current of 4 lights. I would also not recommend fitting 4 lights with a standard 45amp alternator, as they will be drawing around 35amps combined, which isn't leaving much headroom for the ignition system and any other accessories such as the radio, heater and heated rear window, as well as the standard headlights. 2 lights can be run fine off a standard alternator. You can get uprated 70amp alternators for about £60 from Minispares and ebay if you are fitting 4 lamps. Another thing to consider when you are wiring up your lamps is to route the cables as you go, before you cut them to length, it can be very annoying when you have got it all working and then realize you cant route the wires where you want. Now onto the wiring itself.
You will need:
Good quality wire rated at a minimum of 30amps to be safe. (colour coded is best, red for positive and black for negative, blue is optional for the main beam feed)
An inline fuse holder with 20amp fuse.
Spade, butt, ring and (optional) bullet connectors, I will explain why these are optional later.
A 4 pin relay rated at a minimum of 30amps.
Firstly, mount the spot lights to the car, this will allow you to cut the wires to the correct length so you don't end up with loads of spare wire, or not enough.
All the wiring will be kept near to the front of the car, so find an area on the inner wing at the drivers side (assuming a RHD car) near to the front to mount your relay(s). Once you have decided where you are mounting the relay you are able to cut wires to the right length.
The first step is to disconnect the negative side of the battery, this is essential as you will be working with the main live feed to the engine bay and you could short something out, cause a fire, seriously hurt yourself, or all of the above. Next you will want to remove the grill so you have access to the starter motor, as this is where you will be connecting the live feed from. You will be able to see a thick black wire running to the starter motor, and securing it in place will be a nut (cant check the size as my car is in the garage having some welding done) which you need to undo. You then need to get a ring connector that will fit over the bolt that you just removed the nut from and crimp it onto the end of an inline fuse holder, put this ring connector over the bolt and refit the nut, making sure it is nice and tight and making a good connection. if your relay isn't close enough to connect it straight up then you will need to use a tube like (butt) crimp connector to add some additional wire to the fuse holder, then cut to the correct length to run to the relay. Add a spade connector onto the end of that wire and connect it up to pin 30 on the relay.
Next you will need to take a feed from the main beam circuit to activate the relay when you put on your main beams. The best place to take the feed for this is the black block connectors behind the grill (also one of the main things that stop your headlights working as they are prone to corroding). The connector that has blue wires with white traces is the main beam feed. There should be a spare hole in this block connector where you can add another bullet connector, if this is the case then use blue wire if possible, otherwise just run some red wire to this connector. If this part of the loom has been modified and there is no place to connect to, then you will need to cut the blue and white wire mentioned. Strip the ends of these wires and use a butt connector, putting the original wire and your new feed in one side, and the other end of the original feed in the other. Run your new feed to the relay, cut to length and add another spade connector, connect this feed to pin 86. (If fitting 4 spot lights you will have to run 2 feeds from the blue wire, simply add the second wire into the other side of the butt connector or connect both wires into the bullet connector. This is also where the bullet connector is optional.)
The next step is to determine how you are running the wiring into the lamps. Some spot lights will earth through the body of the light and though the brackets so only require one wire. Wipac spot lights are a good example of this. If your spot lights come with a connector attached then make use of it. Connect a spade connector onto some red wire and connect it up to pin 87 on the relay, then run the wire to a few inches from the first wire. You will need to then add another butt connector here, and run 2 wires from it, one to the first light, and one to the light at the other side. Use the appropriate connection onto the existing spot light wire if possible, otherwise use a spade or bullet connector. It is a very bad idea to run the wire straight into the light as you will need to be able to disconnect the spot lights to remove the grill in future. If the lamps need an earth feed too, then you can run a black wire from the lamp back to the relay, using the same butt connector method you used for the live feed.
The last step is to connect all the earth wires. The best thing to do here is use the mounting point you made for the relay. Run a wire from pin 85 on the relay to a ring connector, and add a ring connector to any other earths you may have. then line up all the ring connectors behind the relay and screw them into the inner wing. Now go round and double check all the connections are secure, re attach the battery earth and you are ready to test out your new lights!
If there is anything I missed or you feel I should add then do let me know. if you don't feel happy doing this yourself then buy a ready made wiring loom for the lights, or pay a professional to do it for you. The last thing you want is your pride and joy going up in smoke. I would of added a few photos to make it a little easier but my car is having some welding done at the garage so this wasn't possible.
