Headlight Bulbs

[Leodis]

Hi I've got chance of some 80w dip 100w mainbeam bulbs can i fit these or will I need to change wiring/relay


Cheers Steve

[Morr]

Hi I've got chance of some 80w dip 100w mainbeam bulbs can i fit these or will I need to change wiring/relay


Cheers Steve

I would reccomend upgrading the wiring first, as the Toyota headlamp wiring loom is not the heavest and may well have difficulty with the extra load, Use the existing feeds to the bulbs to switch new relays to supply current direct from the batterys via some heaver than stock wiring.
This mod is reputed to give increased light output on many vehicles with stock bulbs including the Surfs, and is a must with uprated bulbs. I learned this the hard way many years back when after about half an hours drivin on my newly installed 120w (think they were 120's, over 100 anyway) main beams the lighting stalk in my Fuego burnt out, had to drive over 50 miles on unlit roads with 1 sidelight and a mate holding a 2 D-Cell torch, not fun.
Since that I've always fitted the relays and new wiring anytime I've uprated the bulbs and never had another problem

[Morr]

I've had some pm's asking for more info on how to modify the wiring loom, hope this drawing helps....

This mod ideally requires 4 relays, one each for high and low beams for each headlamp. You can get away with 2 using one for each beam connected to both lamps, but this way if you get a failure you will loose both lamps. 4 is best.
You will also require heavier wiring and new connectors for the back of the bulbs. If you can't source these locally, www.vehicle-wiring-products.co.uk/ looks good.

Note: I've forgotten to put it in the drawing, but its imperative that you use either a fused relay, or fit an appropriate fuse in the line bringing the new live feed to the relay. This new line (in green) should come directly from the positive terminal of the battery and the fuse should be located as close to the battery as practical.

[AndyLala]

Morr,

Nicely done... So, what minimum gauge wire should that be? and what should the current rating on the relays be?

Say 60amp capacity on the wiring and 30amps on the relays... obviously different draws on different bulbs... etc...

Toying with the idea of making some kits up. Want to do mine, might as well make a few sets up.
AndyL

[Morr]

Morr,

Nicely done... So, what minimum gauge wire should that be? and what should the current rating on the relays be?

Say 60amp capacity on the wiring and 30amps on the relays... obviously different draws on different bulbs... etc...

Toying with the idea of making some kits up. Want to do mine, might as well make a few sets up.
AndyL

Found this on the web.....

The first thing you have to do is determine the current you have to carry. For DC circuits, that’s relatively easy. Some equipment on a car is rated directly in current draw. Auxiliary fans, fuel pumps and things like that are rated in current draw - Amps. Some equipment is rated in Watts - mostly the lighting equipment. The power requirement in Watts will be printed right on the bulb or stamped in the base. To come up with amps use one of the formulas shown here.

Current in Amps = Power in Watts/Voltage in Volts

Current in Amps = Voltage in Volts/Resistance in Ohms

Current in Amps = The Square Root of Power in Watts/Resistance in Ohms

Let’s calculate for a typical 100 Watt Driving Light - the power required is 100 Watts and the voltage is 12 Volts - so the current requirement is 100 Watts/12 Volts = 8.33 Amps. Actually, it's somewhat less than that because the rated output of a lamp is figured at 13.5 volts, not 12 volts - 13.5 volts is typical when your engine in running and the Alternator is working correctly. We'll use the 12 volt figure anyhow - Let’s assume you have to run a wire 6 feet from a relay to the lamp - check out the chart below. Using the 10 Amp column you’ll find that you can run 10 Amps on 15 feet of 18 AWG with only 1/2 Volt drop. Go to the next size larger for a safety margin and you’re at 16 AWG (See the note below on output losses with lighting). Now in reality, you have to balance the mathematical results with mechanical reliability. Me, I’d go to 14 AWG as the wire and connectors are physically stronger — plus I only buy three sizes — 14, 12 and 10 AWG. Those three and crimp-on connectors are readily available just about anywhere. And except for primary circuits, those three sizes will cover just about anything you want to wire in a car with an adequate safety margin.

So how much current are you drawing in your car total? Is your Alternator big enough? Let’s say you have four 100 Watt Driving Lights and you’ve upgraded your OEM Lights to 100 Watts each for another 200 Watts. Now you’re at 600 Watts, or 50 Amps, just in forward lighting! Got an electric cooling fan? Another 8-12 Amps, the same as your heater fan. Dual Horn - 12 to 20 Amps. Stop Lights - 2 Amps each. Marker Lights - 0.5 Amps each. Ignition - 8 to 12 Amps. Fuel Pump - 4 to 8 Amps. When you are installing auxiliary equipment in your car or truck, it's always a good idea to keep track of how much current you're drawing total so you can make sure your alternator is up to the job!

Note that wire sizes for lighting is more critical than for other applications — The rated output of a lamp is figured at 13.5 volts, not 12. So with a 1/2 volt drop you are at 13.0 volts. And at 95% of the rated voltage, you are only putting out 80% of the rated luminous intensity - for a 100 watt lamp that’s only 80 watts!! Get what you pay for and figure to the high side when you are sizing wire for lighting.

Maximum length in feet for car wiring
return to text
Wire Gauge Current Load in Amps @ 12 Volts DC
4A 6A 8A 10A 12A 15A 20A 50A
20 AWG 26' 17' 13'
18 AWG 37' 25' 18' 15' 12'
16 AWG 56' 37' 28' 22' 18' 14'
14 AWG 90' 60' 45' 36' 30' 24' 18'
12 AWG 143' 95' 71' 57' 47' 38' 28'
10 AWG 227' 151' 113' 90' 75' 60' 45'
8 AWG 363' 241' 181' 145' 120' 96' 72' 29'
6 AWG 585' 390' 292' 234' 194' 155' 117' 46'
4 AWG 925' 616' 462' 370' 307' 246' 185' 74'
2 AWG 1515' 1009' 757' 606' 503' 403' 303' 121'
1 AWG 1923' 1280' 961' 769' 638' 511' 384' 153'
0 AWG 2427' 1616' 1213' 970' 805' 645' 485' 194'

Calculate the current load and find the next highest on the
top row. Go down that column until you find the length you need to run. The wire gauge required is shown in the far left column.
The maximum lengths are based on a 1/2 volt drop over the indicated length.
To be safe, always choose one wire size larger than you need for the required current carrying capacity and length. For example: You’ve calculated 10 amps load, over a length of 15 feet. The chart shows that 16 AWG is suitable. Choose 14 AWG to allow an adequate margin for safety.

Long winded, but looks usefull.

[AndyLala]

Blimey Morr,


spot on... out comes the calculator....

Where did you find it... pointer to the original source...?

andyL

[Morr]

Blimey Morr,


spot on... out comes the calculator....

Where did you find it... pointer to the original source...?

andyL

I did a search on google using the following as keywords
"100w bulb" current wiring relay
The 10th item returned is http://forums.nasioc.com/forums/arch...p/t-55276.html

Its a post on the North American Subaru Impreza Owners Club

Scroll down, its the last post.

[AndyLala]

Thanks Morr,


much appreicated. I'll put together a shopping list.

andyL

[poppy986]

Bulbs

Hi Andy
Have you looked in Halfords they do replacement bulbs upto
30% and 50% brighter than original bulbs without the need
to rewire etc.
I have fitted what they call "ice blue" bulbs far beter
than the normal type bulb brighter and a blue sint to them.
Worth a look?
Chris

[AndyLala]

Carefully read the description.... they appear 30% brighter... they aren't 30% brighter... Having previously measured my leads into the bulbs for resistance, they rate quite high... spotted that IPF do upgrade wiring looms for the head lights to improve existing or for their upgrade lamp units, that do exactly what Morr has outlined above.... thought it might help mine... Already got those PIAA Super Whites, they claim the same (although the light they put out is whiter....) and cleaned the insides of the headlamps.... (got the most difference cleaning the dust out of the rear bulbs and lenses...)


andyL

[Leodis]

Thanks for that Morr even I can follow that.



Cheers Steve

[AndyLala]

OK, Gentlefolk.

I am going to build myself one of these.
And make a kit for the 2nd Gen Surfs amongst us.

Anyone want one? PM me.

AndyL

[AndyLala]

I've had some pm's asking for more info on how to modify the wiring loom, hope this drawing helps....

This mod ideally requires 4 relays, one each for high and low beams for each headlamp. You can get away with 2 using one for each beam connected to both lamps, but this way if you get a failure you will loose both lamps. 4 is best.
You will also require heavier wiring and new connectors for the back of the bulbs. If you can't source these locally, www.vehicle-wiring-products.co.uk/ looks good.

Note: I've forgotten to put it in the drawing, but its imperative that you use either a fused relay, or fit an appropriate fuse in the line bringing the new live feed to the relay. This new line (in green) should come directly from the positive terminal of the battery and the fuse should be located as close to the battery as practical.

Morr,

I finally have a loom in my hand but am having major problems... overheated the existing loom a couple of times, with no major damage.

I am getting really confused.

H4 Bulb.
Looking at the back of the bulb.

Common - left hand connector
High Beam - Top connector
Low Beam - right hand connector
(I am sure these are wrong... but cannot find a reference anywhere as to what the connections on the bulb should be)

If you take the common and top connector on the OEM Loom to energise the coil on a relay, I can then use the relay to pump positive to the top connector direct from the battery, and Negative to the common (left hand) connector direct from the battery. The bulb shouldn't mind whether it is switched on either side of the element?

Or should I wire the bulb the same way, ie. live all the time to the common connector and switch in the negative with the relay...?

Am I missing something?

[rusty]

Use a volt meter to determine what powers what on the wiring loom, then wire it as per Maurice diagram and it should work.
Fuse each pair of relays with a 20amp fuse

(Edit)
Maurice, no offence meant but have you got the wiring round the wrong way???
I've got mine wired like this
30 = +ve from battery (via fuse)
85 = Earth
86 = Feed from existing wiring loom
87 = Feed to bulb

[AndyLala]

I have a problem with this.


The headlamp loom runs switched earth, not switched positive.
So the common connector on the bulb is live, and the loom switches the earth in, making the circuit.

So if that very circuit energises the coil in the relay, you should be able to switch positive to the bulb, by earthing the common terminal on the bulb.

(same as the side lamps and indicators incidentally)

That bit is fairly straight forward.

Two things.
1) the circuit is designed to see a resistance, the bulb... hotter/brighter it gets the higher the resistance... all we will have is a coil in the relay...
Do we need a resitor in that circuit...?

2) which terminal is supposed to be the common terminal?