Wiring the front fog lights - Bulb warning system question

[BenH]

Front fog lights are almost useless for this country (unless you're a teenager in a Citroen Saxo) so I was thinking of wiring mine into the main beam circuit to add to the main beam effectiveness. They make a difference in dark wet country lanes, but I get tired of turning them on and off all the time if I meet oncoming cars.

In the owners' manual for my '95 W210 E200 there are grave warnings about the risk to the bulb-sensing system of changing the wiring of the lights, so I'm wondering whether anyone knows how sensitive this system is, and whether running a feed from the main beam wiring through a relay to the fog light circuit would do any harm.

Does anyone have any suggestions? Thanks in advance.

Ben Harvey

(Edited by BenH at 10:37 am on Aug. 28, 2002)

 

[Barnie]

Wiring the front fog lights

Hi Benh
Your question regarding the wiring of the fog lights into  the head light system fills me with HORROR!. YES it would cause  serious problems with the bulb failure warning system , which by its very nature has to be extremely sensitive.
One also has to consider the requirements of the M O T test. If the fog lights are made to operate in tandem with the obligatory head lights then they also become subject to all the test requirements.
THINK before you leap!! & fit auxilary fog ligts instead.
let me know
Regards  Barnie

 

[rpalmeida]

Wiring the front fog lights

Whereas I agree with Barnie, I have an idea that will probably work.

As Barnie says, you cant play with the wiring around the bulb area (ie after the bulb monitoring system) because it will mess up the monitoring.

However, I dont see why you couldnt add a relay which would be operated by the switch side of the headlight feed (ie up by the multi-stalk-control). The output of the relay would then be connected across the fog light switch wiring, ie to similate the fog lights being switched on.

Remember to remove the relay before going into the MOT test ! (ie put it on a plug in base)

R

 

[BenH]

Wiring the front fog lights

Sorry to panic you Barnie!
My idea was simply to augment the *main beam* lights with the fog lights - not the dipped beam. I thought that the main beam requirements for the MOT are simply that there should be a main beam, but the pattern of light (or the number of lights) is not important. Otherwise, how would rally-based cars get through MOTs with racks of lights on the bonnet?

I figured that the bulb-sensing system would be pretty sensitive, which is the reason for asking before trying but I just wondered just how sensitive it would be. I had a quick look up around the steering column stalk and at the fuse panels, but I can't even *find* the relevant wiring, let alone suss out which way to fit such a relay link as rpalmeida suggests. There seems to be no labelled fuse for the fog lights, and I can't hear a relay clicking either within the dashboard or under the bonnet.

I just thought a simple feed from the battery live to a relay circuit would be sufficient, and is perfectly removable when/if I want to sell the car later on.

External, bolt-on spot lights on an E-Class would be rather ugly, IMHO. A bit 'Max Power' for me, I'm afraid!

Cheers,
Ben

 

[Koolvin]

Wiring the front fog lights

it is very easy to do! here is how mine was done ;pull out the headlight plug thingie:

and then get a multimeter and a freind to do the light controls while you see what contact pin does what - then just re-arrange them! easy peasy the contact pins look like this:

oh and be carefull who you call boy racer's who use there fogs etc - I do agree in small cars it looks **** - but big beefy car's it looks tuff (but its become a epidemic in my area even bluddy black taxi's do it)

oh and for MOT - most garages won't even know - just tell them they are the flashers and if they do fail you (higly doubtfull unless they own the same merc) then just re-do the wiring before the MOT only takes like what 5 mins?

for maximum effect I even wired up my front indicators with City lights - but thats iilegal but nobody know's hahahahahahah

 

[BenH]

Wiring the front fog lights

Err... thanks. I think. No reference there to the bulb-sensing system at all, so I'll wait for a second opinion on this.

Oh, and *anyone* who leaves their fog lights on with their dipped headlights when it's not foggy is a muppet. They are either a dozy fool who's forgotten that they're on, or they're a Max Power fool who thinks it looks cool. Makes no difference what size of car it is.

All IMHO, of course.

(Edited by BenH at 12:31 pm on Sep. 2, 2002)

 

[Barnie]

Wiring the front fog lights

Hi Ben
Further to my previous reply I HAVE been looking at my own manual & have gleened the following info which might help ,
(1) Any auxilary lights fitted must be fused UP LINE from the sensing unit.
(2) On MB 500E models the fog lights are replaced by AUXILARY MAIN BEAM HEAD LIGHTS. using the same head light assembly. this of course begs the question what does the 500e use for Fog Lights ? which same question would apply to you if & when you do convert.
I personaly find my FOG LIGHTS very efficient and more usefull than any that I have used on previous car,s I have owned.
regards
Barnie

 

[BenH]

Wiring the front fog lights

Thanks Barnie. Interesting what you say about your manual. Was this a workshop ('Haynes'-type) manual, or your Mercedes owners' manual?

I don't plan to get rid of the fog lights, even though I never use them. I just plan to make them come on with the main beam, but remain switchable in the normal way.

Does anyone know where the sensing unit is wired into the lights? Is it at the lights themselves, by the fuse/relay or at the control switch?

Thanks again in advance.
Ben

 

[Anonymous]

Wiring the front fog lights

I'll have to keep my eyes open for these "Tough" cars, and see how "Tough" the driver looks when he is clutching his fixed penaly ticket!!

 

[BenH]

Wiring the front fog lights

No, no, Dave. They aren't 'tough' - they are 'tuff'! :biggrin: The difference to a 17-year old is probably huge, although I'm at a loss to understand why.

Anyway. Thanks for the laugh - first laugh I've had today, and it's 3pm!

 

[Barnie]

Wiring the front fog lights

Hi Ben
The manual I am refering to is my car,s owners manual  for a MB 200E.
I am unable at this moment to locate the exact position of thr "Bulb failure sensing " unit but the "Haynes Manual wiring diagram indicates an" exterior ligts control unit" to which ALL the exterior lights are connected ,including the warning light for the   "bulb failure
warning system".However Ben I will .try & find out for you. Regards Barnie
PS Do you by any chance know of where I lay my hands on a manual, or exploded view of a Stromberg carb 175cdt or a Pireburg carb 175CDT ?? The operation of these carbs is quite simple realy ,its the bolt on electrics that are giving me problems. thanks Barnie                    

 

[Koolvin]

Wiring the front fog lights

lol

 

[steveperry]

Wiring the front fog lights

Hehe Dave, good one :biggrin:

BenH,

I find that my front fogs are more than adequate and if you have the correct wattage bulbs fitted they shouldn't dazzle on coming drivers. I know what you mean about 17 year old "Saxo drivers" who like to light up the fronts of their cars like Christmas trees.

I have noticed that some MB drivers prefer to drive around with side-lights and fogs only (leaving dipped beam switched off) and in those cases I haven't been dazzled or blinded, although I am amused as it gives the car a "cross-eyed" look, especially on the W201 and W124.

You said "so I was thinking of wiring mine into the main beam circuit to add to the main beam effectiveness" I don't think it would, main beam is meant to illuminate far into the distance, whereas the reflector geometry for fog lights is meant for wide dispersal close to the car, I certainly notice this when I use my front fog lights, the road to the immediate sides of the car gets most of the light with very little projected into the far distance.

I'd be tempted to leave as is.

Just my two-penneth

S.


*edit* p.s. if you want the real racer Saxo look, then think about fitting blue LED lights to you windscreen washer jets heh :biggrin:

(Edited by steveperry at 1:58 pm on Sep. 7, 2002)

 

[BenH]

Wiring the front fog lights

My windscreen washer jets are below the level of the bonnet - nobody would be able to see them, except me! Don't imagine that I haven't thought about it, though! :biggrin:

You're absolutely right about the beam pattern of the fogs - they do simply illuminate the verges and not really ahead at all. On winter nights, though, around country lanes, this is very useful. It also allows you to see around tight bends before your car turns enough to use the main beam.

Adding the fogs to the main beam was just an idea that I had that would actually allow me to use the front fogs. At the moment they're just ballast! Purely ornament. Drivers who use them in normal non-foggy driving are inconsiderate, in my humble opinion, because they're usually as bright as the dipped beams. Twice the amount of light = twice the dazzle. There's no excuse (unless one dipped beam bulb has failed), so I keep switching them on when they help and off when a car approaches. "How much simpler this could be if they just came on with the main beam automatically," I thought.

Ah well. Another great idea that's destined never to reach production!