Help! Fog Light Only Works With Dipped Beam.

[fry61]

How strange that no wattage is specified --- maybe type approval covers this --- otherwise it's as much use for rear protection as the side lights --- concrete parachute springs to mind.

[Guest snowy2]

Those seem to be the current regs, recent changes apply to marking on heavy goods only.

another pit fall is the minimum height for headlights.......C+U and old SVA state 500mm from road to center of light (dip beam cut off) the IVA manual gives no firm guidance but its quick referance drawing guide shows measurement to base of headlight........one that for one of my cars is a potential nightmare if it needed an IVA.

[Nigel Rogers]

Hi All,

 

One of my IVA fail points was fog lights coming on with the side lights, so I fitted a normally closed relay using the Brown/Black wire from the light switch (133 Diagram 2. Exterior lighting - head/sidelamps. Models from 1990 onwards) which is power off when main beam switched on. The problem with this is that the fog lights work with sidelights when the ignition is switched off.

 

The IVA manual section 28 Rear Fog Lamps Note 4 1) states that: The rear fog lamp(s) may continue to operate until the

position lamps are switched off, and the rear fog lamp(s) must then remain off until deliberately switched on again.

 

My car didn't fail on the fact that the fog lights don't have to be deliberately switched on again. So I am in the position that I have fixed the problem that the car failed the IVA for, but only when the ignition is switched on and the car doesn't actually comply with the IVA manual as it's written.

 

I think the fog light regulations are possibly the most confusing part of the IVA to comply with .

[Guest snowy2]

weird thing is that in my opinion fog lights i would ban from cars tomorrow, i mean how useful are they?

if you comply with the law they would be used for perhaps 1 0r 2 times a year (i drive 100,000 miles a year all over the country in all weather conditions, and i rarely see fog thick enough....)

so what purpose do they serve? they can dazzle, they can mask brake lights, and if your behind someone using them there is no distance that you can be behind them when there not bothering you until they are invisible.

it should definitely be illegal to use them when someone is behind you.

they are in my opinion the one thing that is a positive safety hazard on our roads and the sooner the authority's tackle this instead of "speeding" at 80mph on motorways the better.

[Guest snowy2]

here is a circuit that will operate the fogs as the IVA requires...

the relay is an ordinary 4 pin relay, if you only have 5 pin relays to hand just do not use the 87a connection (normally closed) the momentary switch can get its power FROM ANY CONVENIENT PLACE! as you touch the fog light (momentary switch) it will trigger the relay to switch on because the relay has a feed back loop it will stay switched on UNTIL the power is switched off by turning the side lights off. when the sides are switched back on the fogs will NOT switch on until activated again.

Edited July 12, 2013 by snowy2

[Guest snowy2]

[fry61]

Don't think this way of wiring the rear fog will comply with IVA.

[Pete Mar]

Might be wrong but this looks like the lamp will work with the side lights. Which means it would not comply with the regs. Has to only work with dipped and main beams.

[Guest snowy2]

dip and main beam only is real easy.......just use the dip/main beam supply not the sides......simples

[Pete Mar]

You actually need a supply from the switched side of the dipped and main beam relays as the dipped beam relay switches off when you switch to main beam. Which also means you need a diode in both supply's or they will supply pore to each other.

[fry61]

Headlight & sidelight switch on right of column feeds high beam/dip beam switch on left of column ;cut into this feed wire(doesn't matter whether poz.or neg.)& feed your rear fog switch, output from fog switch to relay or direct to rear fog lamp. Other side of relay coil/lamp to poz.or neg depending on above voltage at feed wire. No diode required.