I posted a thread with this title a while ago Louis. Both Bertie and TMs posts contain really useful information. I've had extra front lights fitted since CZ but haven't got round to wiring them in as of yet.

Mine were going to be additional driving lights. I've fitted LED bulbs in them to reduce the strain on the wiring. Relays are a really good idea though.

Any ideas which of the cables that is?

I dont have relays fitted on my lights at the moment so I'm probably not gonna wire them in till thats' done. Bertie what relays did you use? Got a link?

Anyone with a late model car, which includes both of yours Louis and Sam, will already have two relays fitted, with wires running to the lighting switch and front of the car. If you've disabled the dim-dip set up (and you should have) then you've got the perfect headstart towards wiring in auxiliary lights, be they fog or spot. Just need a bit of swapping the wires around.

Side or dip - if the fog's really thick, they're most useful with side-only.

Sam - any "normal" 20-30A relay.

Yeah, I did mean that, but was just pointing out that the fogs do work with just the sidelights on.

Joolz you're a genius: talk me through this.

I've disabled the dim/dip thing by moving some wires around and bridging the connections on one of the relays (in the thread on it somebody posted a really good diagram). This solved the switch over heating.

How can I use these relays to connect additional lights?

Also.... is it a good safety thing to fit a dip/highbeam relay?

<points upwards> They're just relays.



If you relay them, then you no longer take the full current through the light switch - only a small switching current. If your light switch currently gets warm, it will no longer do so. That can only be good - both for the longevity of the switch and for the amount of electrickery getting to the lights. But your fingers will get cold.

usually just bin them as the terminals are often corroded

safer still to use 15a fused relays usually about £4 each which also protects the circut should it short out.

Sean

to wire a relay...
the relay has 4 terminals marked 30 86 87 & 85

From the switch the wire that used to feed the lights is cut in the engine bay and attached with a crimp on insulated female terminal to leg 86 on the relay. From leg 85 a wire goes to earth.

From the battery+ via an 15A in line fuse, to the 30 leg on the relay, you just go straight to the leg if its a fused relay. From the 87 you can connect the other bit of the existing wire to the lights that you cut.


Louis
For a fog light feed from the green terminal under the light switch to a new illuminated switch then from the switch to the relay 86 then to earth from 85.

then from battery + via fuse to 30 then to the rear of the car from 87

cant remember the nos on the bottom of the crossover relays in the citroen bodgery but its one or t'other ( usualluy a little diagaram on the top of the relay) its the terminal thats not normally "in circut" or the lights would be on all the time untill you switched on when they would go off........im confused now


Sean

Thanks sean, adrian and joolz and others who have helped. Earlyer I wired them to workwith an illuminated switch that doesnt illuminate typical, anyway it works and I've got them working minus the relays and stuff that melt my brain I'll show you what Ive done when its complete, then you can tell me where I've gone wrong and when my cars gonna blow up

To be honest I hadn't fully thought it through, or expected it to be such a revelation. But so long as you've got the last edition of the Haynes manual, published in 1990, then on page 202 you'll find the wiring diagram for the dim-dip system. Looking at that in conjunction with the diagram Adrian posted on the last page should enable you to work something out. Any more detailed instructions would depend on whether they were spots or fogs, and exactly how you wanted them to work.

Does anyone know if its a legal requirement to have the front and rear fogs operated by different switches? I know it's not an ideal situation to have them come on together, as the fronts will invariably be used when it isn't foggy, but it would simplify things not to have to add another switch.