Brake Lights To Fogs

[Billsy]

OK MOT approaching! Can anyone tell me what I need to do to convert my Altezza’s inner brake lights into fog lights? I want them to revert back to brake lights when the fogs are swithed off. This must have been mentioned before, but I can’t find anything. I’m guessing I just need a switched live to the two bulbs? That sounds way to easy. Any help appreciated

Billsy

[SHAHZ]

Theres quite a few post HERE should be able to find what you want somewhere there :) ;)

[Rob]

yes just a switched live to the inner 2 bulbs, but remember to disconnect the brake light feed to them

[Billsy]

yes just a switched live to the inner 2 bulbs, but remember to disconnect the brake light feed to them

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Thanks Fluff but I want to keep them as brake lights when the fogs are switched off so I probably need a relay or something right?

Thanks for the search Shahz but I can only see posts on the fog light to brake light mod and I want to do the opposite but keep the 5 brake lights when the fogs are off

Am I making sense guys?

I really don't want to nail a fog light to the bumper so please help

Cheers

[MacRS200]

yes just a switched live to the inner 2 bulbs, but remember to disconnect the brake light feed to them

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Thanks Fluff but I want to keep them as brake lights when the fogs are switched off so I probably need a relay or something right?

Thanks for the search Shahz but I can only see posts on the fog light to brake light mod and I want to do the opposite but keep the 5 brake lights when the fogs are off

Am I making sense guys?

I really don't want to nail a fog light to the bumper so please help

Cheers

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If you wire the brake lights + volts through the N/C contact of a SPCO relay and feed the coil off the fog switch it will open the brake light circuit if the fogs are on :D

[Billsy]

If you wire the brake lights + volts through the N/C contact of a SPCO relay and feed the coil off the fog switch it will open the brake light circuit if the fogs are on :D

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Oh right thanks Neil its easy then :duh: not!

Sounds like a job for my local auto electrition. Unless you can post some very easy to follow instructions.

Billsy

[MacRS200]

If you wire the brake lights + volts through the N/C contact of a SPCO relay and feed the coil off the fog switch it will open the brake light circuit if the fogs are on :D

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Oh right thanks Neil its easy then :duh: not!

Sounds like a job for my local auto electrition. Unless you can post some very easy to follow instructions.

Billsy

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Sorry it is pretty easy. One quick question are you using the same bulbs for fog and brake

Will knock up a quick wiring diagram for you and post later tonight with more detail on the mumbo jumbo :D

[Billsy]

Sorry it is pretty easy. One quick question are you using the same bulbs for fog and brake

Will knock up a quick wiring diagram for you and post later tonight with more detail on the mumbo jumbo :D

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Good man Neil :) Yeh was hoping to use the same bulbs. Will Maplin sell the relay?

[MacRS200]

Sorry it is pretty easy. One quick question are you using the same bulbs for fog and brake

Will knock up a quick wiring diagram for you and post later tonight with more detail on the mumbo jumbo :D

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Good man Neil :) Yeh was hoping to use the same bulbs. Will Maplin sell the relay?

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Ok bloody Oven packed up tonight so only just manged to get it fixed

SPCO = Single Pole Change Over relay, its got 3 contacts called Normally Open (N/O), Normally Closed (N/C) and Common (Com). The Normally bit means what the state is with no power on the realy coil, N/C is connected to the Com, N/O is not, power on the coil the reverse N/C is not connected and N/O is :D

So if you wire the power from the brake switch to the Com and the feed to the bulbs to the N/C the lights will work as brake lights.

Take the switched live for the fogs to one side of the relay coil and connect (Delete "another wire") (Insert " a diode") from the same terminal to the N/C terminal. Connect the other side of the coil to a good ground, when you switch on the fogs the N/C contact will open breaking the circuit for the brake lights at the same time as feeding power to the bulbs and you got fogs on all the time :D

Maplins will do the relay, quote them "RS part no 351-639". Wired as above the coil will only draw 40mA so should not overload the fuse, the contacts are rated at 16A so that will give a max of 96 watts per bulb for brake lights, should be plenty.

You will also need a relay base to plug the relay into, quote them "RS part no 400-9130", this gives you the screw terminals to connect to. It also lets you change the relay easily if it packs up.

Total cost from RS £ 4.95+VAT, Maplins should be about the same or a bit less :D

With a bit of sticky velcro you should be able to find a place to hide it in the boot lid.

Sorry I didn't get time to do a diagram, if the above is not clear let me know and I will "nick" a bit of work time tomorrow to draw it up.

[Billsy]

Ok bloody Oven packed up tonight so only just manged to get it fixed

SPCO = Single Pole Change Over relay, its got 3 contacts called Normally Open (N/O), Normally Closed (N/C) and Common (Com). The Normally bit means what the state is with no power on the realy coil, N/C is connected to the Com, N/O is not, power on the coil the reverse N/C is not connected and N/O is :D

So if you wire the power from the brake switch to the Com and the feed to the bulbs to the N/C the lights will work as brake lights.

Take the switched live for the fogs to one side of the relay coil and connect another wire from the same terminal to the N/C terminal. Connect the other side of the coil to a good ground, when you switch on the fogs the N/C contact will open breaking the circuit for the brake lights at the same time as feeding power to the bulbs and you got fogs on all the time :D

Maplins will do the relay, quote them "RS part no 351-639". Wired as above the coil will only draw 40mA so should not overload the fuse, the contacts are rated at 16A so that will give a max of 96 watts per bulb for brake lights, should be plenty.

You will also need a relay base to plug the relay into, quote them "RS part no 400-9130", this gives you the screw terminals to connect to. It also lets you change the relay easily if it packs up.

Total cost from RS £ 4.95+VAT, Maplins should be about the same or a bit less :D

With a bit of sticky velcro you should be able to find a place to hide it in the boot lid.

Sorry I didn't get time to do a diagram, if the above is not clear let me know and I will "nick" a bit of work time tomorrow to draw it up.

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Neil that is awesome. After reading it a few times and looking at a couple of electronics web sites, it actually makes sense to me :P One of the sites mentions the need for a “protection diode” “to protect components from the brief high voltage 'spike' produced when the relay coil is switched off”. Is that needed? or is it intended for PCB components? I look forward to your diagram. Cheers

[MacRS200]

Diagram for wiring

That one won't work be back later

[MacRS200]

Somehow this went twice How do you delete a post you make in error

Ok may as well use it as I posted it :D

On the diode wouldn't worry, only thing I don't know is if the dash will show a fault with the rear lights due to changed load on brake circuit.

[MacRS200]

This one will :D

For diode use "RS part no 447-0829" cost £ 0.57 each but you got to buy 5

[Billsy]

This one will :D

For diode use "RS part no 447-0829" cost £ 0.57 each but you got to buy 5

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Thanks Neil. It's starting to look a bit beyond my ability now tho How long do you think it will take a qualified auto spark to do the job?

[MacRS200]

Thanks Neil. It's starting to look a bit beyond my ability now tho   How long do you think it will take a qualified auto spark to do the job?

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Only difference between this and the description is the use of a diode to connect the N/C and the power feed to the coil.

Assuming the switched feed for the fogs is still around in the boot lid reckon it would take about an hour to do. Not that complicated mate, you just need to find the feed from the brakes and the switched feed for the fogs. Cut the brake feed before the first light and joint with the relay, stick the fog feed into the relay and connect a ground :P You may need to connect a wire to one side of the diode as I can't remember the positions of the contacts.

[MacRS200]

Billsy

Been thinking bout this and the relay is a load of pants You just need a diode wired like this :D

[Billsy]

Billsy

Been thinking bout this and the relay is a load of pants    You just need a diode wired like this  :D

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Nice one. That looks a bit easier. Is it worth putting a diode on the feed from the fog switch?

[MacRS200]

Yeh should really, won't affect operation but stops the fog feed wire going live when you brake. Now needs to be like this :D

Much more professional mate and as you need to buy 5 you might as well use them :winky: