Reference Drawing from Factory Exploded Manual.
Amazon
Tail-light Fixture Restoration Notes 11/08-R. Kwas
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General
Removal of the Fixture from
Vehicle
Mechanical Refurb and Improvements
Electrical Refurb and Impovements
Optical Refurb and Improvements
Final Assembly
Bench Test
Installation onto
Vehicle
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Links to Discussions on the Subject
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General: Amazon taillight fixtures have the logo “Robo” and number 670614 stamped into them. They are made of simple formed sheetmetal with a plating which is mildly reflective when new and only slightly more reflective, after forty years of age and surface rust, than the background of gas station Elvis-on-Velvet-paintings [Reference 1]. Since the taillights are quite small to begin with, I thought it was time to show how to clean them up, and get the most light out of them possible. This really is a safety issue. I have thought about modernizing them with LEDs, but that is not as simple as one might think, because of the very narrow light output beam which these have (it's not enough to just plug in replacements!), so is left as an article for another day!
Reference Drawing from Factory Exploded Manual.
Excerpt from Wiring Diagram.
Note: Taillight fixture wiring color codes for both sides are the same, and only
upstream of the incoming connector is the Left is Green and Right is
Blue color coding used for directional blinker circuits.
This allows fixutres to be interchangable, side to side.
A number of causes exist, which can all contribute to poor lamp electrical performance. They just about all involve poor connections in the current path which would serve to decrease voltage at the lamps themselves. I have highlighted these, and they are all covered here. The plan was to make all electrical connections in the current path as good as possible, and to also improve the reflectivity of the fixture to make best use of the maximun light output. When finished, I was quite happy with the effectiveness of the finished product during BenchTesting, considering it took a mere two hours to complete one fixture (not including removal from vehicle), and I expect this renewed effectiveness will last for a good long time!
Removal of the Fixture from Vehicle: I used a loose, spare fixture for this article, so I didn’t first have to remove it from the vehicle, but removal can be quite difficult itself given corrosion of the hardware, and possible stripped Phillips screwheads (29, 30) at the lens. Before any attempts to remove, and possibly doing more damage, I highly recommend applying penetrant to the upper and lower threaded (brass) inserts and bolt from inside the trunk, into which the lens bolts screw, a week, then again immediately before turning the screws! If the Phillips slots of the securing screws are bunged, it may even be possible to double-nut the back end of screws in the trunk to get them to start turning. Once the lens and chrome bezel have been removed, the fixture itself is held to the body by two tiny selfthreading screws (31). These lowly two screws are in fact quite important in that they are also the current carrying return paths for all lamp currents...if they are not particularly snug, you have just found Cause One of the reasons the lamps were not at their full brightness! After also unplugging the associated six-contact electrical connector (28), the fixture can be removed. Once removed, the fixture may look similar to this one:
Before Pic of a reflector as it might look when first removed from vehicle...not
so pretty!
It doesn't look much better from the back side! Yellow
shows lamp locking pin is not
even in it's recess, and wire end at red looks pretty grodey too. Blue
highlights the lower brass insert .
Mechanical Refurb and Improvements: There is not much to the reflectors
mechanically, but rust and / or green and white stuff in the lamp sockets can
make the lamps difficult to remove or install, to say nothing of the poor
electrical connection which it is likely providing...
Cause Two for poor lamp function. A
penetrant will help with removal of corroded lamps...having access to the socket
and spring from the back also helps. In my spare sample, the lower (backing)
lamp was apparently corroded into place so well by dusty white corrosion, that
the glass envelope broke before it would budge when the last person tried to
remove it...I resorted to ripping out the remains none too ceremoniously with
needle nose pliers,
but I kept all force and damage to lamp base to save socket! The
crimped-on wire termination was missing when I finally got it out!
Removing remains of a broken lamp base from socket.
The socket base contact is found to be missing.
The folded over sheetmetal tabs of the socket, where they lock the socket to the reflector, are also subject to corrosion. This is definitely in the current path so will cause a subtle, easy to overlook electrical resistance which must be eliminated. I did not take this apart, not wanting to cause more damage than good, but simply prepared the outside surface for soldering also by wire brushing with a high-speed hobby-grinder with wire wheel attachment (wear eye protection!... the fine wire bristles are miniature arrows as they are flung off the wheel at high speed!). Once I had a clean shiny surface, I used a miniature butane gas torch to get enough heat into the joint to get proper solder flow across the gap, making a Gas-Tight-Joint and pretty much incapable of developing a resistance to lamp current...EVER again! Cause Three eliminated!
Preparing socket tabs for soldering by wirebrushing (red).
Yellow is critical lamp locking pin recess which must be clean and shiny.
Soldered lamp socket tabs (reds) make for an optimal long-term connection.
Lamp locking pin recess is shiny clean and likewise ready to make a
perfect connection.
Electrical Refurb and Impovements: All wire terminations connecting to the lamp contact should be soldered. This will assure the best connection between wire and crimped-on terminal. But with all the surface corrosion present, it will likely take some time for the flux of a quality lead/tin solder (like Kester brand 60/40) to cut through, but a good joint from wire to crimp termination must be established! I purposely left a small mount of solder on the part of the crimp which protrudes over the insulated disc in socket and which connects to the solder contact at lamp base. This eliminates Causes Four and Five!
Soldered Wire ends assure proper longterm connection to
lamps.
Missing end is replaced with a crimp terminal custom cut, bent to shape and soldered.
Although the entire round base of the lamps is in the socket, and theoretically making contact all around, fact is that the tiny recess of the socket which receives the locking pin of the bayonet lamps is really the predominant current carrying path because this joint is where the pressure of the spring in the socket is concentrated. It must therefore be cleaned to a shiny metal perfection! I used a micro wire brush for this, but a hobby knife or emery board will do nicely. When a lamp is reinstalled, the use of Anti-Corrosive Zinc Paste (ACZP) on lamp bases as well as this surface of the socket (especially the locking pin of lamps) will keep the connection protected and conducting at its best for a long time. Cause Six!
After this complete treatment, I expect the lamps will burn out before they need to be moved to clean a poor connection, and get them working again!
Optical Refurb and Improvements: After it is assured that the lamps will be working at full voltage, the light that they emit needs to be reflected out the lens and not eaten up in the fixture [Cause Seven]. The best thing is a mirror finish, but since my brother-in-law doesn’t own a plating company, I decided on the next best thing to optimize the reflector...I used a layer of stick-on, highly reflective, self-adhesive (real metal) aluminum tape. I chose this shiny tape over silver or “chrome” (not really!) paint, whose reflective characteristics have never impressed me.
I used 60 Grit to remove most of the toughest surface rust from the reflector, leaving a decent surface for the aluminum tape to adhere to. The round wire brushes intended for prepping the inside of 1/2" copper plumbing pipe before soldering, worked nicely for cleaning up the inside surface of the lamp sockets. After removing most of the surface rust present and cleaning with carb cleaner to get the best adhesion, I applied 1 1/2" wide self-adhesive (real) aluminum tape in horizontal stripes starting from the bottom (like shingling a roof...water runs off not in). The thin metal stretches so can be burnished into the complex shape of the reflector...overlaps of the thin metal are not the end of the world. Beware: This is real thin metal which is capable of slicing skin just like a blade! Shop gloves will prevent slicing and dicing yourself... Once the new reflective surface is in place, a hole can be cut for the lamp socket with a hobby knife, and edges trimmed with shop scissors.
Self-adhesive alu foil is highly reflective, and from the
light pattern,
it's clear that the original concave shape of reflector was really quite good!
Final Assembly: Installation of the (cleaned up) lamps is naturally with a light film of ACZP on the entire base, and a dab particularly on the locking pin and base contact(s). Install normally, being aware that the middle lamp is a dual filament lamp which has its locking pins at staggered levels and only inserts and locks in one position.
Bench Test:
I assembled a three-color lens and chrome bezel onto the plate and connected
power to each lamp. I was quite happy with the overall result at a nominal
12V...I expect the result in a running vehicle (with upwards of 13V system
voltage while charge system is pulling it up) will be even better. Frankly,
with this renewed level of performance, I don’t see much reason at this point
for changing over to LED light sources!
That was rewarding in it's effectiveness and actually fun as restoration projects go!
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After Pic of the refurbed and improved Amazon tail light fixture
...and that's not even the brighter brake light energized!
Installation onto Vehicle: Use ACZP on six conductor connector terminals, two tiny mounting screws and finally two bezel screws...that should satisfy for a looong while!
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Links to Discussions on the Subject:
Thread about inproving taillight performance : http://www.brickboard.com/RWD/volvo/735472/444-544/brighter_tail_signals.html
Thread about LED taillights: http://www.brickboard.com/RWD/volvo/1120248/120-130/anyone_running_led_tail_lights.html
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The terms Robo and Volvo are used for reference only. I have no affiliation with any of these companies, other than being a satisfied customer and occasional mechanic on their products, in order to keep them working for me, and to help other enthusiasts try to do the same. The results presented here are from my own experience, and can be used (or not, and used strictly for your amusement!) at your discretion. As with any recipe, your results may vary! As always, if you can supply corrections, or additional objective information or experience, I will consider it, and consider working it into the next revision of this article...along with likely the odd metaphor and maybe wise-a** comment.
You are welcome to use the information here in good health, and for your own non-commercial purposes, but if you reprint or otherwise republish this article, you must give credit to the author or link back to the SwEm site as the source. If you don’t, you’re just a lazy, scum sucking plagiarist...the Boston Globe wants you!
