Hey all,
after measuring the voltages at the headlamp bulbs of an executive running standard wattage bulbs, and the improvement gained by fitting a harness makes it well worth it.

The standard wiring is only roughly 1.25mm2 (high beams - good for about 12A) and 0.85mm2for the low beams (good for about 8A). The standard low beam is 55W, so this is 9A through wiring really only designed for 8A, and the high beam is 60W + 55W = 18A (running through wiring best for 12A).

This explains the voltage drop measured at the bulbs - this car was at 11.5V (lowbeam) and
11.2V highbeams) at the bulbs (with 13.2V at the battery). This means that 1.7V was being lost as heat in the wiring and connections - with P = IV, this means that 20W is being lost as heat! EEK!

Halogen bulbs produce most of their light at their rated voltage, and their output falls exponentially to the power of 3.4 as voltage drops.

European bulb manufacturers (Philips etc) rate their bulbs at 13.2V for full output. When the operating voltage drops to 95 percent (12.54v), headlamp bulbs produce only 83 percent of their rated light output. When voltage drops to 90 percent (11.88v), bulb output is only 67 percent of what it should be. And when voltage drops to 85 percent (11.22v), bulb output is a paltry 53 percent of normal!

This means that the lowbeams are running at about 60% of their output (ouch) and highs at around 53%. No wonder they look yellow!

With the new harness (and overwatt Philips 100/90's) the voltage measured at the lamp terminals was 13.0 (lowbeam) and 12.9 (highbeam) - this represents an improvement of 1.5V Lowbeam and 1.7V highbeam - both bulbs are producing roughly 95% of rated output at idle, and when the engine RPM increases, they end up at over 100% rated output (yes, they can do this - doesn't affect life).

The output was also seriously good (as good as a H4 HID kit I have seen fitted to these headlamps) - very nice for country driving, well distributed beam with good side illumination
(unlike the parabolics).

Part List - If you want to make your own.

Relays - Narva Part Number 68000, 12V 40A X 2 ($9.95 each)
Fuse Holders - Jaycar Part Number SZ-2041, Waterproof 12V 30A X 2 ($3.65 each)
Fuses - Narva Part Number 52830BL, 12V 30A X 2 ($0.50 each)
Bulb Holders, Narva Part Number 49894, 12V H4 100W max X 2(H4 only) or X 4 (low + high or parabolics) ($6.95 each)
Crimps - Narva Part Number 56044BL, Insulated 1.5-2.5mm2, 6.3mm blade female X 8 ($0.35 each)
Crimps - Narva Part Number 56078BL, Insulated 1.5-2.5mm2, 5.0mm Ring terminal X 4 ($0.14 each)
Contact Connectors* (Aka. Scotch Locks) - Jaycar Part Number HP-1206 X 4
Cable - DSE Part Number W2027, Double insulated twin 1.8mm2 (26 X 0.3mm) conductor X 2 ($3.29/metre)
Cable - DSE Part Number W2260(red) W2262(black), single core 1.2mm2 (32 X 0.2) conductor X 2 ($0.43/metre)
Heatshrink - Jaycar Part Number WH-5602, 6.4mm Black with heat sensitive glue, ($3.45 each)
Cable Ties - Jaycar part Number HP1203, 15 X 200mm ($1.95)
Split Loom Tubing - Jaycar Part Number HP-1224 - 10mm ID X 2M - ($4.45)

*Evil things - use solder + tape in preference to these! They do fail down the track.

Harness Notes:

These parts are recommended for reliability and safety. Chinese made relays don't last! Hella, Bosch or Narva are reliable and only cost a few $$ more. Narva crimps are pretty good, the plastic insulation on the crimps doesn't fracture or crack with heat like some cheaper ones - On the subject of crimping - never use cheap (single contact) crimpers - they suck badly at holding the wires properly - use proper rachet crimpers with adjustable pressure for joints that will last (and not overheat/fall out) - they only cost $40 or so.

If you use overwatt bulbs, they can only be used in glass lensed headlamps, and only buy overwatt bulbs from Philips, Osram, Narva and Hella.

Cheap ebay blue bulbs and Ebay overwatts are a recipe for disaster...

Cheers
Heath Young

Excellent post Heath

Are there some chances you can draw a diagram and post so we can all see the process.(and maybe see you efforts with a digi camera).

Sound awesome. Then we can use it as Sticky in FAQ.

Seriously, well done and great contribution.

Excellent post Heath

Are there some chances you can draw a diagram and post so we can all see the process.(and maybe see you efforts with a digi camera).

Sound awesome. Then we can use it as Sticky in FAQ.

Seriously, well done and great contribution.

I agree, I have always wanted to upgrade the standard lighting, just not sure how to do it.

No problems - I will knock up some circuit diagrams for everyone in the following configurations...

1) Executive Headlamps - H4 only
2) Parabolic Headlamps - H7 and H1
3) Parabolic Conversion - Converting from Executive Headlamps to Parabolics
4) Executive Conversion - Converting from Parabolics to Executive headlamps

Also I will find the pics I took when I was making it.

Cheers
Heath Young

I must concour batman...lol no its a good post as i have been thinking about upgrading my lights for a long time now.

and with regards to the single contact crimps... DONT DOO IT... hes soooo right... i had to re wire my entire stereo system because of cheap crimps.

Okay so how much get you to make a harness for me! Please!

Great article Heath.

As far as I recall, only high beam or low beam are on at any one time, not both together.

Further to your note about higher wattage globes, it is also preferable to use glass reflectors and glass lenses, although this is not possible with most body shape integrated lighting. So I would suggest that 90/100W (low/high beam) is the maximum used in glass lens/plastic reflector housings and that high beam is not used for anything over a short time (1 min) when stationary and that the housing is monitored for discolouration and/or melting during initial use.

I've made a replacement harness for nearly every car that I've owned, but I didn't feel a need to make one for my TL. The light pattern appears to be good and the brightness is better than the usual offerings. I'll have to measure the voltage drops to see if MMAL made any improvements.

Ken

Great article Heath.
As far as I recall, only high beam or low beam are on at any one time, not both together.


Correct - in the H4 setup (although on Flash To Pass both filaments are lit). In the combined H7/H1 setup (parabolics) the low and high are on.



Further to your note about higher wattage globes, it is also preferable to use glass reflectors and glass lenses, although this is not possible with most body shape integrated lighting. So I would suggest that 90/100W (low/high beam) is the maximum used in glass lens/plastic reflector housings and that high beam is not used for anything over a short time (1 min) when stationary and that the housing is monitored for discolouration and/or melting during initial use.


Yep - I forgot to mention this ~ It is in my headlamp FAQ though... I have seen as high as 130/100's (EEEK) available. IIRC it goes High/Low (not low/high)



I've made a replacement harness for nearly every car that I've owned, but I didn't feel a need to make one for my TL. The light pattern appears to be good and the brightness is better than the usual offerings. I'll have to measure the voltage drops to see if MMAL made any improvements.


Yep - Its well worthwhile - I would still measure voltages on the TL, the freeform Hella reflector used in the TL's is far more efficient than the TJ, TE etc.

Cheers
Heath Young

No problems - I will knock up some circuit diagrams for everyone in the following configurations...

1) Executive Headlamps - H4 only
2) Parabolic Headlamps - H7 and H1
3) Parabolic Conversion - Converting from Executive Headlamps to Parabolics
4) Executive Conversion - Converting from Parabolics to Executive headlamps

Also I will find the pics I took when I was making it.

Cheers
Heath Young

Excellent, thank you very much Heath, you one of the few members on this site I consider a huge asset to the forum.


Okay so how much get you to make a harness for me! Please!

I was thinking the same thing, Headlight improvment kits?lol

If there is enough interest, I can probably knock up some harnesses in whatever configuration you like (as shown below)

Available Configurations:

Standard:
1) Executive Headlamps - H4 only - $120
2) Executive Headlamps - H4 and H1 - $135
3) Parabolic Headlamps - H7 and H1 - $135

Conversion:
4) Parabolic Conversion - Converting from Executive Headlamps to Parabolics - $135
5) Executive Conversion - Converting from Parabolics to Executive headlamps - $120/$135 (if H1 connectors supplied)

1) This allows you to run either good standard wattage bulbs or over-wattage (100/90 is about as far as you would go) bulbs in the standard executive headlamps without the attendant voltage droop issues found with the standard wiring. Keeping the standard highbeam bulb (55W) has a lower impact on the voltage drop as the current across the wiring has now halved.

2) This allows the above, plus allows you to run an overwatt H1 highbeam (100W max)

3) This runs both the low and high beams via relays - and in glass fronted parabolics, allows Osram high output (65W) H7's to be used along with 100W H1's - DO NOT USE OVERWATTS IN PLASTIC (ONE-PIECE PARABOLICS) - the plastic will yellow due to the higher heat and UV content of the light.

4) If you are installing Parabolics onto an executive, this greatly simplifies the wiring - just install this harness, and go!

5) Most people will ask why, but if you do a LOT of night driving where you need superior highbeams with long distance vision, along with good side vision, you NEED the Hella Executive headlamps - put some overwatts in, and the parabolics wont even come close... (parabolics have very little spread, and extremly bright forground lighting, along with extremely wide angle highbeams - typical US DOT pattern, Hellas are ECE).

You can work out the totals for the parts, add in the time to get all of the bits, add in the labour (find an auto electrician who charges less than $50 per hour for labour!) to make the harness, and you will see that the premade harnesses are a pretty good price. I'm not doing this for the money, but I would like to break even/not work for free...

The harnesses come with everything you need to install (minus stuff like screwdrivers etc obviously) and come with pdf instructions + pictures for installation. I provide scotch locks but STRONGLY RECOMMEND that they not be used - joints should be soldered and taped.

I will post some pics of the completed harness for everyone tomorrow hopefully...

Cheers
Heath Young

hmm sounds interesting, altho i dont really get it....is this harness something to replace the existing wiring for the headlights, in order to make them more efficient/brighter?

my TR's headlights are horribly dim and yellow even with newish bulbs, so this harness would fix that?

"2) Executive Headlamps - H4 and H1 - $135"

Okay put me down for one of those and let me know when and where to send the money - very interested!

"2) Executive Headlamps - H4 and H1 - $135"

Okay put me down for one of those and let me know when and where to send the money - very interested!

Also very interested (acctually ready to purcase if your upto itlol ) in the same option as SARRAS, and happy with the price too. :P

hmm sounds interesting, altho i dont really get it....is this harness something to replace the existing wiring for the headlights, in order to make them more efficient/brighter?

my TR's headlights are horribly dim and yellow even with newish bulbs, so this harness would fix that?

Yes - it replaces the thin factory wires that cause a voltage drop at the lights, reducing their output. By allowing a higher voltage to the bulbs, they produce a lot more light (and aren't as yellow).

It also allows higher wattage bulbs to be used to their full potential (ordinarily if you fitted overwattage bulbs they would just draw more current, increasing the voltage drop and making very little difference to the output).

Cheers
Heath Young