Advanced Gauge Lighting Instructions.doc

Advanced Gauge Lighting Instructions

by Toby Erkson

This particular document is for the more advanced mechanic. I do not suggest these procedures be performed by those who are unsure about their abilities or have little experience working on cars or delicate instrumentation. This information is presented to assist those who are contemplating or will be making changes to their gauge cluster.

I was very tentative about diving into my cluster but it turned out to be somewhat easier than I expected (good German engineering helped, I'm sure ). This was performed on my original '95 gauge cluster; I now am using a 2000 Cabriolet gauge cluster so this modification is not necessary with them. Good luck if you decide to dive in and make changes. Remember to be careful because the parts are easily bent or broken and to be particularly careful about static electricity! Also, you cannot buy individual components should you break something. If you damage any part of the gauge cluster or the components within you would have to buy a new unit. Depending on what was broken you may be able to replace it with a part salvaged from another cluster but that is beyond this document, requiring the skill and experience of a seasoned mechanic (be it amateur or professional).

It is assumed that the gauge cluster has already been removed, the white plastic covering the back side has been removed (thus exposing the PC board), and the gauge needles are exposed.

Border the needles with masking tape by placing the tape on the gauge face as shown below. This will allow you to put the needles back in their proper home position.

Place a piece of thin cardboard or several folds of cloth over the top of the gauge that you wish to remove the needle from. Place two thin pieces of metal (I used butter knives) under the round base of the needle with the tips of the metal (or knives) resting on the cardboard/cloth. Slowly lift the strips up to pull the needle from its spindle.

Take the needle and rest it in a vice so the needle face is resting down between the jaws. Using a pointed (but not sharp) tool, you will GENTLY tap the needle from its base by pressing out the two retaining pegs. See the below two pictures for illustration.




Wash your hands or wear nitrile gloves while prepping the needles for paint because any contaminates will mess up the paint. Clean the needles, buff with 0 or 00 steel wool or 400-grit sandpaper, and clean the needles again to remove dust and residue. The needles can be pushed into a piece of cardboard, supported by their two retaining pegs. Try to keep the needle from touching the cardboard so no paint will build-up on their edges.

Give the needles an even and thin coat of WHITE PRIMER. Trust me, black or grey primer makes for a terrible base coat when a day-glo (fluorescent) paint is sprayed on top! The primer is a necessary step because the day-glo paint will not stick to the bare plastic needles. Once the primer is dry, spray the needles with day-glo paint. The primer and day-glo paint can be easily found at any hardware store. I used three thin coats of "Rust-Oleum Fluorescent" red and the results look amazing. VERY IMPORTANT: Let the needles dry completely before handling! Try to handle the needles by the retaining pegs only as much as you can.

Once the needles are completely dry you can press them back into their hubs. I found that I needed to carefully remove JUST A LITTLE material from the end of the pegs so they would squeeze back into their hub. If you goof and the needle is too loose in its hub you can always glue the retaining pegs on the inside of the hub...but you won't be able to remove the needle again so don't make any mistakes!

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Removing the green filter from the top of the gauge cluster is fairly easy. Using a thin bladed screwdriver, carefully pry the white light housing away and up from its base. See the following images:


Carefully bend the light housing back enough to expose the green filter so you can remove it. If you will be installing the UV lamp then cut the power supply metal strips that hold the housing to the cluster.


The filter easily comes out.


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On the back side of the cluster, on the PC board, are eight brass-colored screws. These hold down the black plastic gauge body assembly. Remove the screws and carefully lift up the gauge body assembly -- if you haven't removed the gauge needles then you need to remove the needles before attempting this. You will be prying it up from the PC board. Be very careful not to lose the grey flexible pads that are used by the gauge buttons (odometer and clock switches). The LCDs are now exposed.


To remove the stock green filters you will lift up on the LCD face. Now, the LCD assemblies are loosely assembled and are likely to come apart. Just move carefully and if the flexible side conductors separate from the LCD and/or the PC board just make sure you assemble them in the correct orientation otherwise you make end up with a non-functional LCD. In the image below you can see that my odometer LCD and flexible conductor lifted up together and I was able to slip the green filter out (I called it a gel in the image, think of it as the same thing).


Trace the stock filter on a piece of flexible translucent plastic or a gel from a studio light. I found my piece at an arts and craft stock (Michael's in Beaverton for any locals doing this) though my guess is that a studio gel would probably be better. As you can see, it doesn't take much! I originally cut four filters, two per LCD, but the light output was far too dim so I removed a filter from each LCD (boy, was that fun...not!). I think it's best to only put in one filter per LCD. It will tint the light going through the LCD and allow you more leeway in adjusting light output. I like my interior lighting fairly dim so this worked perfectly; with the two filters per LCD I couldn't see the LCDs unless the interior lighting was on full brightness.


The filter can only fit under the LCD one way. Here you can see the new odometer filter has been installed and the clock filter is the still the stock green.

After changing both filters you can carefully put the gauge body assembly back on the PC board and screw it down snugly. Make sure the grey flexible switches and extensions are in place. If you LCD assemblies were loose they now will get properly positioned when you put the gauge body assembly in place. Press the needles back onto their spindles, positioning the needles between your previously made tape guides. You want a 1mm-2mm gap between the needle hub and gauge face so there is no contact between them. As I found out, any contact will not allow the needle to swing freely and, in my case on my tachometer, give your readout a ticking look like the second hand on a clock. You can now assemble the entire gauge cluster back together.


You will notice that the temperature and fuel gauges are springed: The needle spindle will automatically return to the home position. This makes it easier to position those needles.

The speedometer and tachometer are not springed. When positioning the needle hub on the spindle you may want to first put it on very gently, so its resting on the spindle, and apply a teeny-tiny amount of pressure while rotating the needle counter-clockwise until you feel resistance (the spindle hitting its stop in the home position). Now you can lift the needle off the spindle, position it so it points in the proper home position, and firmly but gently press the hub on to the spindle.

As you can see, it's not quite necessary to tape the needle home positions, however, I would recommend doing this since it keeps your needles in their factory positions.

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Here's a [crappy] image of the 6" UV neon lamp I bought at G.I. Joes in their automotive ricer section. It was inexpensive and plugs into the cigarette lighter.


Here you can see where the neon lamp will sit and the power and ground wires exposed from the plug-in. You will need to disassemble the plug-in and expose the power and ground wires. You need to keep the plug-in because it has the necessary electronics in it to power the neon lamp.


Use RTV (silicone sealant) to secure the neon lamp to the top of the gauge cluster. Make sure the lamp is directly over the light openings.


After seeing that there was light drop-off at the top of the gauges (and two LCD filters was just too much) I had to remove my cluster and open up the light openings. Illustrated is roughly what I did. The material you remove will not be visible -- you won't see the opening -- and it will allow more UV light to reach higher up on the large gauge faces, thus illuminating the needles more when they reach the 12 o'clock position. Don't remove too much material or you will see the openings. If unsure, leave the openings alone and you will see what I mean when things are glowing at night. Then you can remove the gauge cluster and open it up more since removing the cluster is quite easy.


Allow the RTV to dry before installing the gauge cluster back into the dash. Power should come from the same location you use to illuminate the RI gauges. This way the neon lamp is only used when the gauges are lit and thus extends its life. The nice thing about day-glo paint is that it will 'glow' during the day because the sun is an excellent source of UV light, even on cloudy days.

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These pictures were taken in my garage during the day. Below is what the gauge cluster looks like in muted daylight:


This is why I powered my faces to come on with the headlights and not the parking lights. The lit faces are difficult to see in daylight -- black faces would've been better (and a color I prefer over silver).


Because the garage was quite dark, this photograph took 2 seconds to expose and thus the meager light filtering through the garage window curtain and illuminating the dash makes it appear as though the garage was fully lit. Just in case you were wondering. Really, when not rushed I take better pictures. Honest!


Here's a more recent close-up of the cluster. The camera shutter was open for 2-3 seconds which is why you see some of the haze/glare around the cluster. The smaller gauge needles are dimmer than the larger ones but still just as visible. This is because a camera cannot capture fluorescent colors like the human eye.


One thing I have noticed is that if the car interior becomes very cold, like it's been sitting outside in 40°F or lower temps, the light output will be dim. As the cabin heats up so will the neon tube and the light output will reach normal output levels. This appears to be true with the reverse Indiglo gauge faces as well.

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