Fog light setup on UK spec SII

XJ
1

Hello all,

occasionally I feel a set of foglights might serve me and this week I got my hands on some period Hella fog lights at a very reasonable price. I also found the dead wires to be used for the fog lights and wanted to fit the fog lights, ideally using the original light switch. From this forum I learned that on SIII cars the light switch can be manipulated such as to be depressed and operate fog lights in the last position. Some kind of locking ring needs to be removed to enable the push/pull movement.

Now I have two questions: The first relates to the origin of my car, as I know that in the 1970s it was common in the UK to actually have a combination of one fog light and one driving light. Talking in terms of the Lucas Square 8 used originally they came as LR8 for the driving light and FT8 for the foglight. Occasionally, you even find that mix today

grafik
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Just how were these things switched? Were you running on 3 resp. 5 lights, with the foglight combined with outer lights or even side lights and the driving light combined with the main beams and all four main lights? Powering both in fog would sort of defeat the purpose of the foglight. In any case I’d like to wire them up “modern” style, i.e. operating (both!) only with low beam and going out with high beam. What do I have to expect when I kind of restore the factory setup?

The second question relates to the light switch itself. While the parts book describes quite clearly the Lucas Square 8 fog and spot lamps as optional extras (2L 05L), it doesn’t mention a particular light switch for fog lights. Instead two types of switches are indicated (1I 03L): C.38628 for early cars and C.46318 (C.46315) for later cars. As per the car number I’m supposed to have the early type. Could anyone please be so kind as to check the part no. for the SIII switch? In any case I’d be happy about any information on the activation of the fog lights. There should be either a special switch or an “upgrade” mode for the normal switch, shouldn’t it?

Thank you all in advance and enjoy the week end

Jochen

75 XJ6L 4.2 auto (UK spec): .

2

If it’s similar to the SIII switch it is easy. Be careful when removing the assembly, my spare has cracked threads. Then all you have to do is remove a little stop, enabling you to pull out the switch, I believe. I can make pictures tomorrow if you like.
Aren’t they then also switched through the switch?
Also have a good Weekend.
David

3

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If this is an original ‘European’ set-up, Jochen; the light switch should have the fog position ready for use…so…?

Due to European regulations at the time - in ‘fog’; the rear fog lamps are lit, and extra relay connection from the light switch turns on ‘low’ beam. High beam switching is disabled - but I ‘think’ high beam flashing is still active…

If the car is so wired; connecting the fog lamp with the original fog wiring will light it in ‘fog’ - and the low beam will then also come on. Technically, you can connect the ‘driving’ light either to the high or the low beam - at the relay or at the fuse box. In the latter case ‘upping’ the fuse may be required. A relay can be used from these connection points - but a relay will still require a power source…

However, local rules vary; in ‘Europe’ you would have to ensure that the ‘driving’ lamp is not on high beam in ‘fog’. Adhering to the local road code is advisable - and a PO may have interfered with the original set-up for compliance…

Frank
xj6 85 Sov Europe (UK/NZ)
**

4

I started to look up the Series III numbers but it became a bit swampy. For some markets/applications the switch is cataloged individually and in other cases it is listed as an assembly…with the bracket, bezel, etc.

In essence, though, the Series III used two types. USA and some other markets used a switch with a single fog light function/mode, intended for front fog lights only. Other markets, which had both front and rear fog lights, used a switch with multiple fog light modes. I want to say they have six or seven operating modes but I’m not sure.

Not quite sure what you mean by ‘upgrade’ in this case. Are you referring to upgraded load carrying capacity?

Don’t take mine as the final word but I’m not aware of any of the various Series III lighting schemes using separate fog light relays or such. The headlight switch itself has sufficient capacity for intended use. That is, switches for front-only fog light installation will carry the load of front fog lights and those intended for both front and rear fog lights are sufficient for that purpose.

Cheers
DD

5

John Testrake, @Jtestrake, recently fitted square 8’s to his RHD Series 2 XJ12. His installation will be correct, as he is genetically incapable of doing any work on his Jaguars that could result in a Concours point deduction. :slight_smile: Hopefully he will chime in.

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Hello Jochen,
As Bob mentioned, I have Lucas Square 8s on my UK Spec XJ12L. It’s a 74 and has the early switch (C.38628) like your car. The switch has a fog position activated by pushing in and turning.
I don’t have the fog/spot combination; just two fogs. I’ve always thought the fog/spot combo was a series 1 feature and not carried over to the Ser2. They’re wired to the red/yellow trace wires in the harness. They both illuminate in the fog switch position and the headlamps shut off when the fogs are on.

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Thanks for responding, John. I agree that the S1 fog/spot setup was a bit odd, particularly because they were switched on at the same time. BTW, I remain smitten of your dizzy vacuum line, which I admired at a recent concours. The current SU vacuum hose thread (E-type forum) would be an ideal venue for a photo.

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Thank you all for your help, gentlemen!

Sorry, if I wasn’t very clear at the outset: I only want to install front fog lights, no rear fog light (the SII parts book doesn’t even list it). My plan was to use the existing setup as far as possible (i.e. light switch, wiring incl. relays). Without rear fog light I won’t need the more sophisticated SIII switch. - Just to complicate things a bit: the wiring diagram indicates the use of a 5-position switch and of a “rear fog guard lamp”.

So my first concern was that either both lights would do their different jobs in turns or - even worse - simultaneously, as you describe, Robert, and thus at least defeating the purpose of the fog lights.

Thanks, John, for your report - the operation mode you describe is exactly what I’m looking for and I’d be more than happy if I didn’t have to rewire everything to achieve it. And you are probably right: the combined use may have been limited to SI cars as the SII OM only speaks of “fog lights, if fitted” (p. 12). The possibility of spot lamps isn’t even mentioned in the OM. In the same vein the wiring diagram only mentions fog light LH and RH. Nevertheless the sources seem a bit contradictory as the SII parts book expressly specifies “fog and spot lamps” and indicates different part numbers for the fog and spot lamp, resp. clear and amber lenses. However, there is no mention made of the combo on the same car nor any specification of the use on different markets.

As for the switch: what did you have to do to enable the push-in function? When I tried my switch I was unable to push it in.

Finally, I’d like to achieve a setup that I’m used to from modern cars: when turned on, fog lights should operate with main lights on low beam. If main lights are switched to high beam, fog lights should shut off automatically and vice versa. So when you say “the headlamps shut off when the fogs are on” do you mean that only the high beam shuts off - which is necessary - or that the entire main lights (i.e. also the outer lights on low beam) shut off leaving only the sidelights turned on - which I’d find rather scary? The OM strongly indicates that this is indeed the case. As the switch is still original as is the wiring there shouldn’t be any PO interference getting in the way.

Just for the record: the wiring diagram confirms that the foglights don’t have a relay, but the entire current travels through the lighting switch and the red/yellow wire behind fuse #1 supplies them.

If I need to change the operation mode as described anyhow I suppose I could use a generic fog light relay (which I’ve got as a left over from another car), feed the + for the main circuit from the low beam of the headlights and the + for the control circuit with the red/yellow wire from the lightiing switch. Then I’d only have to make sure that the lighting switch in position “Fog” does not interrupt the supply of the dipped main lights. Am I missing anything so far? Has anyone been there before?

Thanks again and have a nice Sunday night.

All the best

Jochen

75 XJ6L 4.2 auto (UK spec)

9

On the USA-spec Series III switch, at least, that is indeed the case. The theory being, I believe, that the fog lamps work best with the headlights off.

Eons ago I bought and installed an “Official Jaguar Accessory” fog light kit that included a relay to defeat this function. That is, the low beam/dipped beam headlights remained on when the fog lights were switched on. This to comply with commonplace state law in the USA.

At the risk of further complicating the discussion my '88 XJS had a headlight switch that, as I recall, allowed fog lamp operation with or without the low beam/dipped beam headlights.

Remove the knob and you should see a little “circlip”. Simply remove the clip. You’ll now be able to use the push-and-turn fog light position.

The Series IIIs also have a fog light indicator in the central dashboard warning light cluster. This is easily brought into the circuit…but I’m not sure if the Series II cars have it

Cheers
DD

10

Thanks Doug,

that’s what I feared - maybe I can source that relay though.

And no, SII cars do not have a warning light for the fog lights turned on.

Best

Jochen

75 XJ6L 4.2 auto (UK spec)

11

it’s a common variety switch-over relay. I might still have the wiring diagram somewhere. I’ll take a peek in my giant folder marked “Old Jag notes and info”

Cheers
DD

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Is it not in the central cluster?
Having any (either low or high) beams on simultaneously with the fogs defeats their purpose somewhat doesn’t it? You really don’t want any higher mounted lamps blur in front of you, at least that’s what I always find to be annoying in non-fog equipped cars.

If I understand you correctly you want them to be on. In that case it’s a simple task depending how the headlight switch is wired up - either when you push it in per Doug the fogs light up additionally, or you wire in a relay that powers the headlights when the fogs are on. And the way I’d like it it would mean a changeover relay that only cuts the two low beams when the fogs are on. In that case when off the headlights are on the NC position and if on this is cut.

David

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In most countries it is illegal to drive on fogs only, Jochen - and illegal to use fogs except in fog or similar restricted visibility. And using high beams in fog is very counterproductive…

There are many ways of skinning this cat - if you look at the ‘European’ wire diagrams for the SIII it shows one of them. The trick here is that in ‘fog’ there is no power on the blue wire in the light switch. Instead, in ‘fog’; switch power is also connected to relay red/blue - powering low beam directly.

Actually, on the later light switch; two ‘fog’ connections are provided - one for the low beam the other for the rear fog guards. But the important thing here is that there is no power on blue in ‘fog’ - if there is; the relay will operate high/low beams independently of the ‘fog’ position…

If so; the alternative is to connect the fog lamp(s) to relay red/blue, using an independent switch between relay and fogs lamps. Which will also work if the light switch has no specific ‘fog’ position. One possibility for the switch differences may be that since there were no rear fog guards for the US markets, the ‘fog’ position was blocked - basically to prevent ‘fog’ switch position to turn off head lamps with the ‘European’ switch…?

Be aware that the outer lamps are ‘two filament’ bulbs; one powered in low beam, the other in high - together with the inner lamps. So you ‘driving lamp’ can be connected at the relay blue/red, ‘on’ for low beam only - or to blue/white, ‘on’ in both high and low. Possibly including a switch for separate control…

Having located the ‘loose ends’ of the front fogs - if one wire is found at the light switch; the driving light must wired from the lamp to its destination…

Frank
xj6 85 Sov Europe (UK/NZ)
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The first part is easy: fog lights up front are allowed in this small part of the world only when visibility is severely impeded by fog, snowfall, rain, smoke etc - not as a daytime running light. OTOH, this rule is way more liberal than the rule for use of the rear fog guard: only for severe fog with visibility of less than 50m and speeds below 50 kph - hence the need for separate switches.

It surprised me that the local laws permit the combination of either low beam headlights or sidelights with (front) fog lights, as the latter setup is very unusual. So, from a legal standpoint I could leave the original setup as is. Though it may well be that in “London fog” foglights function better with sidelights only, under most other circumstances described above, glare is not the main problem and my own experience tells me to usually use the low beam headlights - which is why I’d still prefer this setup. BTW, the first car I used following our conversation is switched to operate the fog lights only with low beam.

I’ll keep my eyes open for the kind of relay Doug mentioned.

Thanks again everybody!

Best

Jochen

75 XJ6L 4.2 auto (UK spec)

15

Sorry, Frank,

I was too slow to understand what your were explaining - it only occurred to me while doing some grocery shopping this afternoon …

Indeed, I found out that the Euro SIII switch, Lucas 202SA, is switched in a way offering alternatives to power fog lights either with side lights or with low beams. The rear fog guard is switched independently anyhow.

Unfortunately, the cheapest switch I found was running around 60 US. So I called it a day and kept pondering until I understood what you were saying:

If I pick the power to the low beams from the main lights relay (brown wire) and divert it to a fog light relay power circuit I can use the red/yellow wire from the standard lighting switch fog position to operate the fog light relay. Then I’ll have to splice this wire to engage the main light relay on low beam. I can do all this without power thieves or other interference with the original setup by making up short connecting wires.The only downside of it is that the fog lights stay on if I switch to high beam. But I think I can live with that.

Does that make sense to you or am I missing anything?

Thanks in advance and enjoy the week end

Jochen

75 XJ6L 4.2 auto (UK spec)

16

I found the schematic for this.

You’ll need a garden variety ‘ice cube’ relay with typical 30-85-86-87 terminal configuation

Terminal 30 = 12v constant voltage (easily taken from solid brown wire at the headlight relay)

Terminal 86 = ground

Terminal 85 = splice into red/yellow fog light wire

Terminal 87 = splice into blue/red low beam wire at headlight relay, upstream of the fuses

Operation:

When the headlight switch is turned to "fog light’ position the low beam circuit is DE-powered.

The relay, triggered by fog lamp voltage, RE-powers the low beam circuit.

Cheers
DD

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Doug outlined one solution, Jochen, allowing for separate switching the fog ‘on’ only in fog position - and not in high beam.

Which will work perfectly - providing you have a ‘fog’ position on the switch. Which is the crux for further work…

The ‘European secret’ here is that there is a ‘fourth’, ‘fog’, position - and wiring of the main light switch to suit. Without a ‘fog’ position on the switch

However; you mention ‘red/yellow wire from the standard lighting switch fog position to operate the fog light relay’. Does this mean you have indeed a ‘fog’ position on the light switch?

As does the ‘European’ set-up - where the fog position is powered in ‘fog’, but the blue wire to the relay is unpowered. (Note; the blue wire powers the high and low beam from the main switch - the switch is dimensioned to carry all the load). The ‘fog’ position powers both the rear fog guards and the front fogs.

I suspect that all 4-position switches are wired the same - but in the ‘US’ version; ‘fog’ position is mechanically blocked.

Now, if you have power on the fog circuit; there is no need for a relay; you can power the fog directly from that position from the switch. The point here is; is blue wire powered in ‘fog’ in your set-up - ie, does your headlamps work?

If not; connect a wire from the switch’s fog position to the light relay blue/red - which will power 'low beam from the switch in the ‘fog’ position.

Re your proposal; connecting the fog lamp to ‘low’ beam on the relay will not light up the fog in ‘high’ - ‘low’ beam is unpowered in ‘high’. But to control the ‘fog’ independently a separate switch is required.

Clarify you switch; Do you have 3 or 4 positions…??

As an aside; some have added relays to the headlamps for two purposes. One; to reduce the load on the light switch and relay. Such relays are then positioned close to the headlamps - to serve the second purpose; to reduce power loss in the wires to the headlamps.

However, as said; both the light switch and the relay are dimensioned to carry the full load…

Frank
xj6 85 Sov Europe (UK/NZ)
**

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Thanks, Doug and Frank!

Indeed, what you describe, Doug, was the solution coming to my mind during grocery shopping!

Frank, yes, the original UK (I strongly assume that it is still original) switch is a four position switch with “Fog” as the last position. P1! Without fog lights installed, this last position is deactivated to avoid the risk that a driver finds him- or herself in the dark, as on “Fog” the main beams are deactivated. Hence the necessity to pull the switch and find that circlip blocking the last position.

P2! I’d prefer to have the fog lights work (a) in addition to the low beams and (b) powered through an additional relay as you describe it close to the fog lights. Using a relay wouldn’t only keep the load from the switch (even though it may be designed for that task), but also be more self-explanatory in the engine bay. For the moment I’ve got a relay and the extra wires, but I’m still lacking the extra tube hiding and protecting the twin wires to the fog lights - don’t know the expression in English. Maybe during the week I’ll be able to test fit the lights to the bumper and measure the necessary length of wires.

Thanks again

Jochen

75 XJ6L 4.2 auto (UK spec)

19

Kabelbaum, perhaps? Just kidding, Jochen…wiring harness, cable harness, wire loom is I think what you’re referring to. BTW, the Series 1 just uses a separate switch for the fogs. Gives you total versatility regarding use with other lighting.

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No, not that easy:-) German “Bougierrohr” seems to translate into spaghetti tube or sleeving.

But, isn’t “Kabelbaum” just a wonderful word? Both figuratively “tree of wires” and phonetically - a bit like “Rummenigge”:wink: Too bad most people on this planet don’t know it …

I just primered and touched up some spots where the anodized black plating on the fog lights rear metal housing had been scraped off - one light is almost like new, the other one has just these barely visible flaws. They must have found their way on a dry shelf basically right after production. Who knows why they were removed at all …

Best wishes

Jochen

75 XJ6L 4.2 auto (UK spec)