The trunk light on our LS400 uses a single #194 Koito T 3-1/4 incandescent bulb (but superb quality) resulting in less than ideal lllumination at night.

I extracted the lens/housing assembly, carefully separated the lense and observed the housing/internal reflecting surface is grey....hardly an optimum relecting color.

see:

http://www.engineeringtoolbox.com/light-material-reflecting-factor-d_1842.html

Material Reflection Factor
(%)
Aluminum, pure, highly polished 80 - 87
Aluminum, anodised, matt 80 - 85
Aluminum, polished 65 - 75
Aluminum, matt 55 - 75
Aluminum coatings, matt 55 - 56
Chrome, polished 60 - 70
Vitreous Enamel, white 65 - 75
Lacquer, pure white 80 - 85
Copper, highly polished 70 - 75
Nickel, highly polished 50 - 60
Paper, white 70 - 80
Silvered mirror, behind glass 80 - 88
Silver, highly polished 90 - 92
Oak, light polished 25 - 35
Granite 20 - 25
Limestone 35 - 55
Marble, polished 30 - 70
Plaster, light 40 - 45
Plaster, dark 15 - 25
Sandstone 20 - 40
Plywood, rough 25 - 40
Concrete, rough 20 - 30
Brick, red 10 - 15
Paint, white 75 - 85
Paint, medium grey 25 - 35
Paint, dark blue 15 - 20
Paint, light green 45 - 55
Paint, dark green 15 - 20
Paint, light yellow 60 - 70
Paint, brown 20 - 30
Paint, dark red 15 - 20

Why Toyota used grey for the housing color is uncertain.... however I realized a reflection factor for mediun grey of 25% offered options for improvement...

Nashua brand Aluminum foil extreme weather foil tape with pressure sensitive adhesive was templated and applied to the interior of the housing to increase reflectivity from grey 25% to Aluminum's 75% rating...enough to discern a noticeable improvement.

The foil tape incorporates a high surface energy adhesive..very tacky and is difficult to work into the housing, but will durably remain in place once smoothed in using a popsicle stick. Cash register paper template helped to pattern the foil.

Trunk light housing and lens
Thin cash register paper used to create template
Foil reflector before pressure-sensitive adhesive backing is removed for application.
Reflectivised housing... like night and day
Many of the LS400 interior light housings are comprised of dark material ??!! (LOW REFLECTIVITY-HIGH LIGHT ABSORPTION), so whether you upgrade to LED or remain with stock incandescent can achieve increased light output by reflectorization of the light housings as described above.

An aside.... your author represented 30 years ago Alba Lamps, a German manufacturer of custom T 1/2 though T 3-1/4 incandescent bulbs and reflectors who did a lot of business with Mercedes-Benz... LED''s of course changed all of that.

Toyota did many things well, but execution of incadescent interior lighting in the LS400 was not their high water mark...

 

You could just replace the old bulb with a LED bulb.

 

I replaced it years ago with a pair of CCFL tubes, and more recently with a couple LED strips.

Needed more even and intense light than the factory bulb could have dreamt to provide.

 

The 194 sized bulbs are rather weak. Some years back I used a 194/921 360 degree replacement. It's not bright by current LED standards at about 40 lumens. This particular bulb is about 1/4" longer so the lens was removed.

 

Nice upgrade Yodaone and thanks for sharing.
Wonder what lighting improvement a combo new reflector material and LED bulb would yield?

 

I just take shiny aluminum foil,mold it to fit light housing and just use the lens to hold it into place.Fast,cheap and works like a charm.My Jeep and VW both have it in tail lights,big improvement over old stock light buckets.

 

lexus had this problem for years, even the newer cars like my GS has this lack of trunk lighting.
as PD stated, nothing an LED or strip cannot fix!

as for this idea, how much more light was emitted? I know it will be difficult to capture in pictures.

 

Love the LED lightstrip answer,a couple nephews have done that in the engine compartments on their off roading Jeeps,really need that light at night miles from anywhere.

 

Numerous LED bulb suppliers claiming their
bulbs offer improvement over T3-1/4 incandescent lamps...yet nothing really appealed to me from a reliability and light output perspective....

After exhaustive research I located DR. LED in Seattle, Washington, offering a complete line of ruggedized LED bulbs to the marine and boating industry....

DR. LED white bulb assemblies incorporate quality Cree LED's that are NOT polarity (negative and positive) sensitive whose circuitry offers uniform light output over a wide voltage range...without flickering.

I dispatched a trunk lamp assembly with the OEM incandesent bulb to DR. LED and they returned it with an 8 (eight) chip plug-and-play LED.

These bulbs could also be employed in our interior door panel lamps..

See:

https://www.clublexus.com/forums/ls-1st-and-2nd-gen-1990-2000/846308-door-panel-interior-lamps.html


Color temperature appears to be 2700K.

Images depicting results:



Original Incandescent bulb in stock gray housing assembly (without aluminum foil in pocket)



OEM incandescent bulb with aluminum foiled pocket. (This posting) Gray plastic is a poor reflective surface and foiling makes a huge difference.



Aluminum foiled pocket with DR. LED lamps...HUGE difference in light output..


The aluminum foil does an excellent job of reflecting light to uniformity...no LED hot spots

 

 

While luggage compartment light fixture with LED bulb is much brighter than stock, the black trim material is a poor reflector of light....
The luggage compartment trim used in our LS400 is well fitting and durable.

Cost effective dark colored (gray/black ) material appears to be reclaimed (recycled) and does not show dirt, scuff marks and stains.

However, black is a poor reflector of light...

Most house ceilings are painted white to improve light reflectivity and perceived room size.

It seems reasonable that a light-colored material would have the same effect in our trunk (where the light fixture is located)

The luggage compartment trim panels covering gas tank/package tray underside appears to be two parts joined..at horizontal and vertical.

Seeking input on aesthetic light colored material or durable coating that could be used to cover ceiling trim cover portion

64717A is luggage compartment trim covering gas tank and underside of package tray panel.

 

The original Dr. LED lamp was a significant improvement over the stock incandescent bulb.

Today I received a brighter, whiter Dr. LED bulb.

A few images taken of bulb illumination is quite visible in daylight


Eight LED chips are correctlyi ndexxed so light fills the lampholder pocket lengthwise.

New bulb photographed in daylight. Slightly more fluorescent than first LED bulb, but better illumination.

 

You are a true craftsmen! Thanks for your efforts on this. Seems like most trunks could use this upgrade.

 

The light output is fantastic.

Night time illumination of trunk;


Open trunk at night using OEM light fixture with Dr. LED bulb.