Honda Prelude UK

Crazy_C · Lude Hero Joined: 26 Aug 2008 Posts: 1268 Location: Kent

Shimee wrote:

Before I even begin I have to give [almost all the] credit to a crippled limey for making this possible. I've wanted to do this for months now and even tried taking the task of finding the "parts" on my own while I was vacationing in Poland during August. Needless to say it failed and so I have Crazy_C to thank for helping me get what I need.

First we modify the front fog harness:

After modifying:

You can see an additional branch splitting near the green plug and one near the ground wires. I basically tapped into the 12v+ white wire AFTER the fuse and am running a 16gauge wire through a high current switch which runs to the rear of my car to the fog lights.

It plugs into the switch as so:

And the switch is located here:

Lights up the little pocket red at night Smile

:

I wrote out the pertinent calculations before wiring anything up. First I counted the number of current sources and then summed up the total current which would now be pulled by the relay. I have two 55watt bulbs in my front fogs and two 27watt bulbs in the rear fogs. Since a Watt is defined as 1 Watt = 1 Volt*Amp, and a car battery puts out 12volts, I get (4.58 + 4.58 + 2.25 + 2.25)Amps or 13.6amps of draw. This doesn't worry me because I have a 15amp fuse inline on the 12v+ lead to the relay, which itself is rated at 40amps. The current draw over the wire for the rear fogs will only be 4.5amps (where the current draw over the wire to the front fogs is 13.6-4.5=9.1amps) and according to standard a 16 AWG (American Wiring Gauge) wire - when made of copper - has a max current load of 22amps. This is idealized current and we will get into voltage drop soon, which involves total wire length.

My plan was to run the wire in a loom along here:

Under the rear seat and with the cable-pulls:

Along the trunk with the cable-pulls:

And to a grommet:

I found a wrecked 5th gen at a junkyard and pulled one of those grommets. There is one on the passenger side where the wire loom for the license plate light comes out through.

So we begin laying down the ground work and plug the harness back in:

Then lay the initial run of wire loom under the carpet:

Feed it through this hole thats just before levers:

Follow the original laid out path and go under the back seat:

Then through the trunk:

And to the grommet:

If you noticed, I've been using 3M double sided tape to control the wiring loom and replace some of the worn foam tape that Honda used. It ironically became perfect for the necessary task.

After running wires the proper length through the grommet, we pop it back in:

Once the wires are on the other side we can begin splicing the connectors to them and finish uporganizing the loom:

And grounded to complete the cicuit:

I originally intended on just getting some bullet connectors because I assumed that these fogs would come with no pigtails. But they did and I immediately noticed something that tickled my fancy.
A few months back I had to replace one of my harnesses to one of my horns because I f@?*$d it up while trying to splice something into it. To my delight I found out that Accords of the same year use the same pigtail to plug into their horns. Remembering this, I realized that these same pigtails are used to plug into the rear fog lights. :sneaky:

Whew. Gutting out the trunk and interior and laying the wiring loom took a couple hours. Time for the pizza mod:

While having some delicious leftover pizza, we can ponder about some food for thought and return to the electrical issue. Specifically, about voltage drop on long lengths of wire.

All AWG (American Wire Gauge) wires come with various ratings, where resisitance-per-100ft is one of them. Like the category implies, wires have a certain amount of resistance per 100ft. In my case, since I used 16 gauge wire, it has a resistance of 0.410 Ohms per 100ft. I ended up using about 15ft from the fusebox down to the rear fogs, which equates to about 0.0615 Ohms over this distance. Using Ohm's Law we have that V = IR [COLOR=black]where V=volts, I=amps, and R=ohms. Since we know the amperage draw of two 27watt bulbs to be 4.5amps and since our [/COLOR]wire resistance is 0.0615 Ohms, our voltage drop is calculated to be 11.82volts. We know already that a Watt=Volt*Amp, so a 27watt bulb at 11.82volts will actually need (27watts)/(11.82volts)=2.28amps or 4.57amps for two bulbs. Hardly 2% more than what we assumed. In engineering we measure efficiency as simply the actual divided by the theoretical times 100, or in terms of battery voltage: (11.82/12.10)*100 = 97.68% efficiency. Anything less than 3% is not acceptable so we hit right on the money.
In fact, there is an equation that allows you to calculate the specific wire size you need for your application. It is defined as CM = (I*L*10.75)/E [COLOR=black]where CM=[/COLOR]wire size in circular mils, I=current, L=round trip length of wire, and E=acceptable voltage drop (usually 0.36). With this equation we get CM=(4.57amps * 15ft * 10.75)/0.36volts = 2047.00 CM. This value falls right in between 16 and 18 gauge wire where CM is 2580 and 1620 respectively. Again, we hit right on the money.

But either way, at this point is time to get some sleep:

So ever loose panel, seat, and trunk article was stuffed back into the car in a highly disorganized fashion:

The next night when I had time to finish, I did a test run:

Success!!

First you have to fit the outline for the rear fog slot:

I used a marker like in n0rmal's write-up to make things easier:

Now time to chop up the bumper so it accepts these fog lamps:

Notice how I cut out a lot less than what I grinded away:

All that's left is to put the bumper back on and pop them in!

Now that it's all said and done, here's some eye candy:

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Shiny · Posted: Fri Sep 25, 2009 8:33 pm Post subject:

Does he think he's hard keeping a mini baseball bat in the car?

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Crazy_C · Lude Hero Joined: 26 Aug 2008 Posts: 1268 Location: Kent

Probably find it's for playing softball. This is the states though so having that in your car isn't even attempting to be hard half the time.

But nuff bout that, you like the final product? I think it looks rather good and like it Very Happy

I know if I get another UKDM lude, I'll twin fog it Very Happy

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Shiny · Posted: Fri Sep 25, 2009 9:03 pm Post subject:

I must admit, they do look good, but i must have used my fog lights like 2 times in the last 5 years.

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Crazy_C · Lude Hero Joined: 26 Aug 2008 Posts: 1268 Location: Kent

Where as I've actually installed hi intensity rear fogs on a spot bar on the back of my old van as well as the roof hi-level and bull bar spots at the front and I used them loads, probably used them every 4 - 5 days when driving country lanes at night without any lighting - they did the job brilliantly! Very Happy

On my normal cars though, I only ever use the front spots, and I just drive with them on as sidelights so see your point there Razz

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nitin_s1 · Posted: Sat Sep 26, 2009 11:56 am Post subject:

One fog light is bad enough in the UKDM bumper so two foglights are even worse.. IMO.. Rolling Eyes

I will be getting rid of my foglight and use one of my reverse lights at fog light so i dont have that ugly foglight in the bumper.. Evil or Very Mad

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JDM-BB4 · Posted: Sun Sep 27, 2009 9:04 am Post subject:

A clean rear bumper looks much better.
Oh well each to their own.

EDMyO!

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Crazy_C · Lude Hero Joined: 26 Aug 2008 Posts: 1268 Location: Kent

Like he was saying, some of us want what they have in the states, and some of them want what we have over here. To us, it's probably nothing amazing, but in the states it's very unusual.

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jozefsan · Lude Hero Joined: 24 May 2007 Posts: 1436

hey dude good work

im just curious what that numbers 1 and 2 ????

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Prelude UK · Posted: Mon Sep 28, 2009 4:32 pm Post subject:

Been there, done that, bought the T-Shirt. I carried out this mod to my previous 1997 Prelude and my current 2000 Prelude. However, by glancing through the above instructions, I get the impression that the above is a lot more complicated way than how I did it. All I did was splice another cable into the existing one behind the rear bumper without the rest of the faffing around shown above

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2000 Honda Prelude 2.2 VTi (H22A8 / BB8).

Crazy_C · Lude Hero Joined: 26 Aug 2008 Posts: 1268 Location: Kent

jozefsan wrote:

hey dude good work

im just curious what that numbers 1 and 2 ????

Heh, he got some stickers and they had a 12 on them, so he just put the 1 & 2 somewhere LOL

And Prelude UK, it's something I've seen a few times over here, but you got to remember that in the UK we actually have fog lights on our ludes, they don't in the states, which is why all the wiring and everything was done as there's nothing to start with like you had.

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Salazar · Posted: Wed Sep 30, 2009 10:24 pm Post subject:

nitin_s1 wrote:

One fog light is bad enough in the UKDM bumper so two foglights are even worse.. IMO.. Rolling Eyes

I will be getting rid of my foglight and use one of my reverse lights at fog light so i dont have that ugly foglight in the bumper.. Evil or Very Mad

I'm thinking the exact same thing Nits! Just found this thread whilst searching the forum for someone who's already done it. I'm sure someone has, any idea where it is on the forum?

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5th Gen R reg 2.2vti, Knightrider Black

nitin_s1 · Posted: Thu Oct 01, 2009 9:24 am Post subject:

Salazar wrote:

I'm thinking the exact same thing Nits! Just found this thread whilst searching the forum for someone who's already done it. I'm sure someone has, any idea where it is on the forum?

I know for sure that PreludeUK has done it in his Red Motegi and also his Silver 5th gen.. Smile

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Salazar · Posted: Thu Oct 01, 2009 10:03 pm Post subject:

nitin_s1 wrote:

I know for sure that PreludeUK has done it in his Red Motegi and also his Silver 5th gen.. Smile

No, no you nonse! Laughing

The 'how to' for that is in this post! Rolling Eyes

I mean someone who has done the fog light rewire so it's in the main rear light cluster, like you mentioned - in the reverse light. Personally I really don't like the UK fog light, a real eye sore in the bumper, and as for 2... wtf!? Laughing

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5th Gen R reg 2.2vti, Knightrider Black

nitin_s1 · Posted: Fri Oct 02, 2009 3:25 pm Post subject:

Lool.. My Bad.. Embarassed

ts really easy though Sal.. You can see the Rear Foglight wires so its just a case of splicing the Reverse light bulb in to them.. Even with me that can't do jack with wirring can do it..

Don't tell Merlin that i still aint wired up my Foglights.. Embarassed

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