Wiring Pajero fog lights as brake lights, but keep as manual fogs...

Submitted: Monday, Feb 17, 2003 at 17:36
ThreadID: 3417 Views:6977 Replies:5 FollowUps:2
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I have an NJ Pajero. As with many Pajero models, it has brake lights in the rear bumper and fog lights higher up on the "corners" of the back.

Many Pajero owners use the fog light switch on the dash to operate driving lights, and connect the fog lights to the brake lights to assist with brake light vision for following motorists (as the existing brake lights are low down).

I would like to do this, but would also like to retain the use of the fog lights as manually operated fog lights.

Any ideas on how I might go about this?

Would it be possible to leave the fog light wiring as it is, so that it can still be manually operated from the switch on the dash, but wire up a relay from the brake lights to the fog lights that switches on when the brake lights are in operation? I only have a limited understanding of car electrics, but logic tells me that the relay should only operate in one direction, so switching on the fog lights manually should not affect the brake lights, but when the brakes are operated the fog lights should also turn on via the relay.

I received only 1 reply on the Vic Pajero Club discussion board when I posted this question, so thought it worth posting here. FYI The suggestion stated:

"Best option is to replace single pole bulb holder with dual pole to take dual element bulb. Leave the current holder tucked away and run a lead from its feed wire to one pole of the new holder and one from the brake feed wire to the other. Then you have both functions separately with no need for a relay." (Thanks, Darryl, BTW)

Any other suggestions on whether this is possible, and if so, how best to do it.

Thanks in advance for any opinions/assistance.

Cheers, Mike.
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Reply By: Suzuki Viagra - Monday, Feb 17, 2003 at 18:32

Monday, Feb 17, 2003 at 18:32
That's tricky - I'd suggest the rear Red fog light should be separated from he brake lights. That's the normal process and it's almost impossible for anyone at home to re-rig any other way.

Third year ina n electronics course or a lot of thoguht would be able to organies it using a combination fo one way diodes and capacitors. I'd rather rig the fog light to the tail light and have the brake light separate, or have a separate fog light globe altogether.

You never want someone else to think you're braking when you're not (unless you're doing something dodgy in front of Mr Plod and then you can ask me about that offline).

AnswerID: 13332

Reply By: ExplorOz Team - David - Monday, Feb 17, 2003 at 20:12

Monday, Feb 17, 2003 at 20:12
The relay is the simple answer. You would set the relay to operate when the brake lights are on and supply power to the + side of the existing wiring loom for the fog lights. This means that when you switch on manually using the switch it willl be as on or off, if on and relay enegrises from the brake light you are only connecing the same + voltage to both lights (this does not really matter), if off and relay energises it will come on as required. Should be easy enough you could also put a switch in line with the rellay supply that will allow you to override the connection of the brake and fog lights together if you wish.

From your write up it sounds that you have it right. If you need some more assistance then maybe I could draw a simple diagram somehow.

AnswerID: 13343

Reply By: Eric - Tuesday, Feb 18, 2003 at 22:36

Tuesday, Feb 18, 2003 at 22:36
The best way to activate you fogs as stop lights is conect a 10 amp diode between the brake light wire and the fog lamp wire, the end of the diode marked with a bar must be connected to the fog lights. Do not connect a relay as previosly suggested as this will cause you brake lights to come on and stay on when you touch the brake pedal with the fogs on manually.
AnswerID: 13430

Follow Up By: Mike - Wednesday, Feb 19, 2003 at 08:51

Wednesday, Feb 19, 2003 at 08:51
Thanks for the advice, Eric. I have never used a diode before, so just wanted to confirm - am I right to assume that it will only trigger one way? That is, if I manually turn on the fog lights it will not connect through to the brakes, but will go the other way (ie from brakes to fogs)? I assume that is why you have mentioned about the bar being at the fog light end, but just wanted to be sure.
Can you suggest where I might buy a diode, and approx what they cost?
FollowupID: 7884

Reply By: Eric - Wednesday, Feb 19, 2003 at 22:32

Wednesday, Feb 19, 2003 at 22:32
the diode will do exactly what you want. Diodes can be perchased from auto elects, dick smith or jayca, price about 60 cents. Other ways of getting a doide would be get one from an old alernator. Good luck. Eric.
AnswerID: 13542

Follow Up By: Mike - Thursday, Feb 20, 2003 at 09:12

Thursday, Feb 20, 2003 at 09:12
Thanks Eric. Should I be placing a fuse along the wire with the diode between the two lights, or is that unnecessary?

Also, sorry to be rather basic about this, but is it simply a case of connecting some wire to the positive of the brake light, connecting this to the non-bar end of a 10A diode, connecting the bar end to another piece of wire and connecting that wire to the positive of the fog light?

What rating wire should I use? I guess 10A if that's the diode you suggest.

Also, I guess it would be easiest to have two diodes and replicate this setup on the other fog light (as opposed to running both wires from one diode from one brake light). Does that sound reasonable...?

Thanks for your help.
FollowupID: 7938

Reply By: Eric - Friday, Feb 21, 2003 at 22:18

Friday, Feb 21, 2003 at 22:18
The lights are already connected together, so only one connection is required, you won't need a fuse or wire, just pick a spot where the 2 wires are running paralel in the loom near the molty pin plug that connects the rear lights to the body loom and solder the diode in there and insulate it well with tape. Eric.
AnswerID: 13713

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