Last modified 21 Sept, 2006

So I have a JDM Revision 3 GT-S turbo and this is important on two angles. 1, it didn't have fog lights / wiring fitted as standard and 2, when imported into the UK they had to rectify that for the MOT. Now the usual ( read cheap ) way to do this is to stick an ugly fog light hanging down from the rear bumper and wire up a switch to the dash and voila it works. The other, neater way is wire the inner pair of lights as fog lights thus leaving the outer pair as tail / brake. The later was the way my own car had been done and it looks grand. I had no worries with that. I have known of a 4 light conversion since I got the car in 2003 whereby the inner lights function as 3, tail / brake and fog and the outer two as tail / brake but never really bothered looking much further into it. Actually I couldn't be bothered lol.

Anyway as is the case there I was happily charging along the road on yet another Applecross jaunt and every time I looked further up the road and saw Lee braking I thought how cool his car looked with the 4 brake lights and the 4 side lights. Now I've seen red MR2's like that and never had the same reaction soooooo I decided I was going to do my car with the 4 lights at the rear.

After reading this fine article on the Owners Club I decided to go and do a bit of investigation on my own lights to find out how they were wired. Turned out to be quite easy. The fog light was only one cable and the tail / brake light was equally clear with the 2 lives and single earth. So armed with the hope I could do this quite easily I found a local breakers yard that had mr2's in and off I went to get the necessary bits.

• 2 x dual filament rear light holders from any Toyota - I got mine from a rev2 mr2 n/a version. Try and cut as much cabling as possible from donor car
• 4 x 5 AMP diodes from Maplin part number UK59, minimum is 5 AMP but you can go higher if the shop hasn't got the 5 AMP units
• some cable crimps and clips also from Maplin
• some black electrical tape from er Maplin

Running cost so far is 6 GBPounds. Now I do have to confess I got the bulb holders complete with bulbs for nowt and if I had not decided to make this change reversible then the cost so far would have been zero so far. Another point to note is the rev2 holders didn't fit straight into the light cluster. Seems like Toyota made the rev3 ones slightly different but you'll see where the lug catches on the cluster so just modify the holder with a Stanley knife until it turns and locks. The live cables are connected together using male / female connectors just in case the MOT man gets a bit funny. Shouldn't be an issue but as least I can disconnect the tail and brake lines in about 5 minutes.

So how do you actually do this then. Well take off the rear light cover as described in your handbook and remove all the bulb holders from the light cluster. Ok, so depending on the wiring of your car the following might not match.

Look at the current brake and tail light holder. The striped white cable is the earth, the solid green cable is the side light live and the striped green is the brake live, easy enough to check. Take the tail / brake light bulb out turn on the side lights and check which contact in the holder has 12v on it. My fog live was wired separately so the colour will change from car to car. Now the advantage of using original mr2 bulb holders is the cabling has the same colour code on it. Makes it a lot easier to wire things up. This is what I did, follow at your own choice / peril. Please read the MR2oc article linked above as it explains why the lights are wired they way they are. I cheated with some of it and used 2 diodes per side to reduce the wiring and trim removal. To join cables or take feeds from the current live cables within the car you can either use Snaplocks or / and Male / Female connectors which can be used to reverse the changes at a later date. So here goes..

• cut the existing inner bulb holder cables - mind and leave plenty of cable on the car and the holder (the latter in case you need to reverse the changes)
• join the earth on the new bulb holder to the earth from the original fog light which you just removed (both white striped)
• join the tail light cable (solid green) of the original wiring from the outside light to the tail light (solid green) of the new bulb holder

At this point in time you should be able to turn on the side lights and get both bulbs to light up for the tail light. I discovered at this point one of my free bulbs didn't work. Typical. I went and bought some bulbs afterwards from Halfords. I actually bought 4 incase I goosed everything lol. If it all works fine and dandy and looks like the pic below (after I had done both sides) then you are ready to move onto the next stage.



The brake and fog light connections are more tricky because you are essentially using one connection on the bulb for 2 separate circuits. What you need to do before joining all the wiring together is to put 5 AMP diodes inline with the lives of the fog and brake cables so they cannot be influenced by each other. If you don't put the diodes in the turning on the fogs will light up all 4 rear lights meaning nobody will know when you put on the brakes. Not such a clever mod.

On my car I found another brake light live that had been cut, presumably to make room for the fog light feed to the inner bulb. So using this feed and a bit of cabling cut from the new bulb holder I used a Snaplock to create a live feed long enough for the new bulb holder. On this newly created feed connect a single diode, black side first. Connect another diode, black side first again, to the existing fog light live on the car. Ok so now you have the brake light feed and the fog light feed from the car wired into a diode each and ready for the final stage. Join the two diodes together into a connector block. The silver / white stripe of the diodes should be against the connector block. If not you have wired the diode back to front. Now wire the the connector block to the remaining live feed from the new bulb holder, again in my case this was a striped green. Time for testing.

If you turn on the side lights you should still have both lights on the modified side coming on together. Now turn on the fog lights, the inner light should now be really bright as the second filament is being used, the outer light should remain as before, no brighter and no duller. If both lights are showing same brightness then you have mis-wired the diodes and the fog light is powering both bulbs. Check the wiring again.



If all is well and only the inner light is bright and the outer one is the usual side light it's time to try the brakes. I used an extending wheel spanner sandwiched between the seat and the brake pedal to get the circuit activated. Obviously if you have another bod there, they can just step on the brake pedal. Ok, both lights on the modified side should show equal brightness and be really bright. Example pic as below



If this all works fine and dandy then the other side is just the same. Took me an hour to do the first side and about 45 minutes to do the other side and this was working on my own. Again I stress the write up is the way I did it and in no way represents the best way of doing it. If in doubt get someone qualified to do it for you or don't do it at all. Total cost to me including 3 spare dual filament bulbs was 10 GBPounds. Not bad at all. Just thinking about my own spare brake connectors I found, it's possible I didn't need to use the diodes since I was using a separate feed. Funny how ideas like this pop into your head at 130am. Ho ho