MK2 / 240 fog lamp wiring

Fitting spot / fog lamps to my 240, I have found the unused wire hidden behind the switch and the unused connectors on the inner wings, have also sourced a four position switch and bezel, question is did the fog / spot lamps only work with the side lamps not with the head lamps? I am thinking I would like them available as extra head lamps aimed out to the sides a bit, maybe I will wire them up differently,

Am I right in seeing no fuse for the lights? the feed seems to come from the dynamo voltage control unit!

The Lucas 4-position switch and factory wiring delivers power to the headlamps/side lamps or fog lamps/side lamps but not both at the same time. To have both powered at the same time, you will need to alter the wiring.

The headlamps and fog lamps are not on a fused circuit.


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I did some work on a customers rally BMW 2002 Tii, we fitted four point belts and some very good spot lamps (2002 head lamps are not generally very bright due to being open to the elements and the reflectors are usually dull) problem was that when you were strapped in you could not reach the dash to operate any additional switches, I fitted a latching relay to power the spots from the main beam feed, first application of main beam you got main beam, second you got spots as well and so on, may think about doing that again, and will add fuses and relays to reduce the load on the original switch gear and wiring,

Just a couple of things to check on.

  • Road rules may - and probably do - prohibit the use of headlamps and fog lamps together. In addition, the use of fog lamps in conditions other than bad visibility warranting slow driving may also be a violation.

  • The full current load is through the switch as you know. Powering the extra lamps might not be good for the switch, particularly if there is some point of resistance due to internal deterioration. (I have had this and found it quite alarming seeing smoke coming out of the dashboard.)

These were built in the days before relay controlled circuits so adding relays into the high load circuits could overcome a slow wiper or dim headlamp. Having a fuse for each headlamp gives an added safety level so that you don’t lose both if there is a fault in one.

I will be fitting for the head and spot lamps relays plus individual fuses on the inner wings where the lamp wiring plugs into the main loom at the ten pin connectors, I will also provide a battery live feed for the relays, I intend to use spot lamps in conjunction with the original sealed beam headlamps, from reading the The Road Vehicles Lighting Regulations 1989 I cannot see reference to spot lamps, only fog lamps, therefore if I call my spot lamps additional main beam lamps I believe they are allowed, I would only use them with the main beams and therefore only in situations when there is no traffic approaching me,

I imported my mk2 from the Netherlands , and the po , who done a bit of rallying , made certain upgrades including having the foglights coming on with the main beams . I would just like the lights to work as they were intended to . How can I change this ?

See if you can find an upgraded circuit that handles this combination. Being used for rallying, it was usual to run these items through relays for reliability, with extra fuses. If that is not evident, it may be as simple as a bridging connection somewhere.

I suggest checking the back of the switch first. If the cross connection is there, you should see the output lead for the fog lights connected to the headlamp lead. If not there, check the harness connectors behind the lights These would both be a potential for overloading the switch, and not recommended, so the crossover would be elsewhere.

Another possibility is that a separate switch (under the dash?) is fitted for switching the fog lamps on at any time. This is a job of perseverance to determine how the circuits work from one end to the other.

I hope this helps.

Our XJ6 has driving lights (innermost pair) that are wired to light with high beam - four lamps - original arrangement. Are you running an alternator, Pat?

yes, XJ6 alternator, and XJ6 pas pump,

Do you have the three or four position main light switch?

It’s a four position switch . The fog position is , at present , redundant . The car is fitted with an alternator , if that helps .

Ok, sounds like they have not just moved the fog light wire that should go to the switch across to the headlamp position on the switch as that position supplies the dip switch and so the fogs would work on both dip and main, you need to look at the 10 pin connector block near to the front of the left inner wing and look for modifications to the wiring, also look / follow the wires back from the fogs to see where they go to, a few decent pictures of the back of the dash area, inner wing area etc. may enable one of us to spot the modifications.

Thanks guys , I’ll do some investigating .