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The mkiv Supra Owners Club

Really simple fog lamp mod needed


Homer

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Does anyone have a wiring diagram or can explain the simplest way to wire in one of the reverse lamps as a fog lamp? I couldn't find a guide in search.

 

I understand how to chop in the wires, but what needs to go back to the dash switch and where does the live need to be taken in the dash? Also, does it need to be fused?

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Yes, should always be fused, however if you use something like the radio feed it will have it's own fuse already. You will require a live and neutral to power the telltale light and then simply run 1 wire to the back where you have done the reverse light change. If you get stuck give me a buzz.

 

EDIT : I used a dash feed, so that the fog light could only be turned on if the lights were on.

Edited by JustGav (see edit history)
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Yes, should always be fused, however if you use something like the radio feed it will have it's own fuse already. You will require a live and neutral to power the telltale light and then simply run 1 wire to the back where you have done the reverse light change. If you get stuck give me a buzz.

 

EDIT : I used a dash feed, so that the fog light could only be turned on if the lights were on.

 

Thanks Gav. Where would you take the live from for the dash feed? I assume the dimmer switch is a good one since it's fused, linked to the lighting system and in an easy position.

 

Would the wire running to the back be a live or neutral, does it matter?

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Thanks Gav. Where would you take the live from for the dash feed? I assume the dimmer switch is a good one since it's fused, linked to the lighting system and in an easy position.

 

Would the wire running to the back be a live or neutral, does it matter?

 

Dimmer switch is an okay one, just make sure of the wattage load. The wire running to the back will be a live one.

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http://www.maplin.co.uk/Module.aspx?ModuleNo=43005

 

Has 3 wires, v+ in, v+ out and gnd, nice and simple.

 

Just checked with Gray as well and it should be good enough for an MOT :)

 

EDIT : I would also of course take it PRE-dimmer, so the fog light doesn't go up and down with the dashlights and you don't put the additional load through the dimmer. Standard fog light is 21w, which is about 1.75A which is comfortably in the switch's range. Of course ideally you would want to put a relay between it to ensure you don't put any additional load on the existing loom.

Edited by JustGav (see edit history)
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I know gav posted a switch with an led in, but I thought I'd specifically mention to anyone else, the fog light switch must illuminate (or I guess illuminate a light on the dash) when on to pass an MOT :)

 

'tis true :)

 

I'm going to try and use the UK fog lamp switch and the fog lamp light in the cluster (which is UK spec so has the bulb). Probably more hassle than it's worth but I like things tidy :D

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  • 1 month later...

Homer, did you manage to get this working?

 

I am in process (Dash is out and in bits.. wires everywhere) of trying to rewire my rear fog. It is currently chopped into the ash tray lighter but doesnt work with standard bulb (Works with LED bulb). However with standard bulb in, when I flip the switch for fogs I get nada lightwise - but I do get smoke :( which is never good.. and the ashtray light dims.

 

I suspect this is because I switched it on whilst the main dash console and top warning lights are all not plugged in (assuming thats not smart also).

 

However now I have all the dash out I want to wire it to the dimmer switch like you have in the hope it will work.

 

Im a complete novice at this - could you list the bits (even if its wire, and the ampage etc) that you used, and which of the dimmer switch wires you chopped into please?

 

Mines a Jspec n/a not sure if that changes anything. I need to get it sorted for MOT.. and obviously as I am not keen on the smoke generated (Came from behind the dash) when the fog light switch was turned on!

 

Cheers!

 

Added pics.. one shows current state of play. Other is the dimmer switch - hoping someone can label the wires.

23022010915.jpg

23022010916.jpg

Edited by JS2004 (see edit history)
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'tis true :)

 

I'm going to try and use the UK fog lamp switch and the fog lamp light in the cluster (which is UK spec so has the bulb). Probably more hassle than it's worth but I like things tidy :D

 

I'll be doing this too. There is a write up on here but its quite complex (for me anyhow). Will be interested to see how you tackle it.

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Im a complete novice at this

 

obviously as I am not keen on the smoke generated (Came from behind the dash) when the fog light switch was turned on!

 

 

It's not easy to give the right advice to a complete novice like you say especially when you've had smoke coming from behind the dash. :blink:

 

I'm sure it would be safer to get someone to do it for you as you've obviously overloaded a circuit which should be investigated, you don't want the car to go up in flames. :)

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Aye - I plan on getting out the Auto-motive spark tomorrow and asking him to wire it up from the stereo supply.

 

The weird thing is the modification had been in there for a while, and was working and passed previous MOT (Previous owner). Its only once I started messing with it that everything went south - and I only did that because the switch wouldnt always light up.

 

Would the little switch itself have a fuse in ? bah - damned thing lol :) Will leave it to the spark, and shell out some more cash.

 

I hate electronics :)

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Not being funny but dont you think you should use a relay?

You need a 4 pin fused relay + a switch, take the power source from the switched live on the lights(fuse box)

on the relay use pin87 to your rear lamp(positive), pin 85 to a commonm earth, pin 30 to Perm live (Batt), pin 86 to the switch.

This will save you burning out the switch long term and gives a safe cuircit.

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Not being funny but dont you think you should use a relay?

You need a 4 pin fused relay + a switch, take the power source from the switched live on the lights(fuse box)

on the relay use pin87 to your rear lamp(positive), pin 85 to a commonm earth, pin 30 to Perm live (Batt), pin 86 to the switch.

This will save you burning out the switch long term and gives a safe cuircit.

 

 

Oops just read you are doing just the one...this is best when doing two, for the one make sure you use a 7-10 amp switch and forget the rest i said...always use a fuse though 10amp is ok.And using the switch live from the lighting cuircit.

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