TR4 Fog Lights

[woodward]

Hello

 

The front fog lights on my TR4 are currently wired from the headlight switch through another switch and then to a relay to the front fogs. I would like to change them so that they will only come on when the headlights are on full beam. I'm therefore thinking about taking a feed off the full beam warning light to the fog light switch and onwards to the relay. As there is a relay, the current should not be that great through the fog light switch. Does anyone see any problems with the setup? I'm not keen to take a feed straight off the dip switch unless I really have too as it's tough to get three wires onto one spade. Any views welcome...

 

Thanks

 

Myles

[RogerH]

Hi Myles,

why not break into the loom in the engine bay. There are plenty of connectors to easily tap into.

 

Wire from the Blue/white at the headlight, to the switch, and then onto the relay coil.

 

Roger

[Grahamgl]

I didn't think that it was permissable to have fog lights and headlights on together.

Graham

[stillp]

I didn't think it was legal to have them switched together.

 

Pete

[MikeF]

I didn't think that it was permissable to have fog lights and headlights on together.

Graham

You certainly can't have spotlights on when headlights are dipped, not sure about fogs but on my eurobox the fog lights do not go off when main beam is selected, which you would think they would if illegal.

 

Mike

[RobH]

On the contrary Graham you MUST have the headlights on but you may only use the fog lights if visibility is reduced. The rule says:

 

You must use headlights when visibility is seriously reduced, generally when you cannot see for more than 100 metres (328 feet). You may also use front or rear fog lights but you MUST switch them off when visibility improves.

[Alec Pringle]

If you need fogs on then you probably, almost certainly, do not need main beams . . . . . which renders the original suggestion barmy.

 

Apart from which, contravening the detail of Vehicle Construction and Use Regulations is always a bad idea.

 

Stick with separate switching and use fogs ONLY in fog - otherwise fit additional driving lights to the appropriate position and with correct controls.

 

Cheers

 

Alec

[tim hunt]

Alec is spot on of course. Surely Myles is talking of SPOT not FOG lights. Why on earth would you want FOG lights to operate with main beams? In conditions where fog lights are beneficial main beams would simply reflect straight back off the fog and effectively 'blind' a driver. In really dense fog even dipped beams will reflect back and under these circumstances it is perfectly permissible to use fog lights as an ALTERNATIVE to dipped headlights (see Roadcraft p35 ) for better vision. Correctly mounted fog lights can be aimed to give a low spread of light to pick out both kerbs without reflecting back to trouble the driver.

 

Tim

[RobH]

Sorry Tim - what you say about backscatter is common sense but Roadcraft isn't law.

 

The Highway Code specifically states in rule 226:

"You MUST use headlights when visibility is seriously reduced, generally when you cannot see for more than 100 metres (328 feet). You may also use front or rear fog lights but you MUST switch them off when visibility improves (see Rule 236). Law RVLR regs 25 & 27"

 

Note the use of the words MUST and MAY ALSO, which implies as well as the headlights, not instead of.

Edited September 19, 2017 by RobH

[stuart]

Obviously that rule must have changed as all the MK2 Jaguars I owned (There were quite a few) when you switched to fogs on the headlight switch it turned the headlights off.

Stuart.

[tim hunt]

Actually not so Rob. It is hard to conceive that Roadcraft would advocate any course of action that was against the law. Indeed, RVLR para 2 ( (ii) provides an exemption from the need to use obligatory dipped beam headlights if, in conditions of seriously reduced visibility a pair of front fog lamps, which is fitted so that the outermost part of the illuminated area of each lamp in the pair is not more than 400mm from the outer edge of the vehicle, is kept lit.

 

Tim

[RobH]

Hmmm. Something odd there then if these documents contradict each other. You are right Tim, RVLR in schedule 6 does say:

 

2. Position–
.............
( i Lateral–

(i)Where a pair of front fog lamps is used in conditions of seriously reduced visibility in place of the obligatory dipped beam headlamps–

Maximum distance from side of vehicle: 400 mm

 

Obviously an area where the right hand and left hand are not talking.

Edited September 20, 2017 by RobH

[tthomson]

Sorry Tim - what you say about backscatter is common sense but Roadcraft isn't law.

 

The Highway Code specifically states in rule 226:

"You MUST use headlights when visibility is seriously reduced, generally when you cannot see for more than 100 metres (328 feet). You may also use front or rear fog lights but you MUST switch them off when visibility improves (see Rule 236). Law RVLR regs 25 & 27"

 

Note the use of the words MUST and MAY ALSO, which implies as well as the headlights, not instead of.

 

This does not state that the headlights must be on Main Beam. Just that you must use Headlights.

If the fog is bad enough where dipped headlights are causing problems with backscattered light, I suggest it might be better to stop, and not drive until it improves.

 

TT

[Andy Moltu]

Conventionally fog lights are instead of main beam and come on with dipped beam.

 

Obviously if you wear a baseball cap (particularly back to front) then you will have them on all the time 'coz ya think it's cool.

 

Spot lights should be with main beam and not when using dipped beam.