W114/115 rear light renovation.

[Mike D]

Okay, okay, we've all done it! You know, dealing with the flickering rear lights/turn signals and brake lights, we've tried everything. Pieces of wire in the sockets to hold the bulbs tighter, blobs of solder on the bulb electrodes, bending the springs to provide more tension etc., etc.

Here's a "step by step" process to get your lights in order. I got lucky on this first set and didn't have to do any major repairs but I have another set in poor shape which I will do a pictoral on later.

First remove the lenses and put them in the trunk. Disconnect the wiring harness. I use a small flat bladed screwdriver to work the harness loose. The old plastic can be brittle so use some care. Depending on the year and model you might have a separate connector for the markers and the license plate lights. Remove the 4 nuts holding the assembly to the body. You need to remove the spare tire for access to the right rear. Wiggle the assembly up over the bumper guards (if it's a '73 or later). I had to loosen the bumper nuts (17MM) to get clearance for mine.



There it is! The taillight of shame. Nice cotter pin holding that turn signal bulb in! And you consider yourself a mechanic!

Remove the bulbs, cotter pins, duct tape or whatever you used to hold the bulbs secure.



GENTLY separate the gasket from the assembly! Gaskets are available but any decent "closed cell" weather stripping will do the job in a pinch.



Spray some lube on the four mounting studs. Don't use WD-40 or any "rust" remover. PB-blaster is okay and INOX works fine but all the other ones will eat the coating off the reflectors.



Using a small flat bladed screwdriver or putty knife, gently and evenly separate the light assembly from the chrome ring (pre-'74) or the mounting body ('74 up). The lower outer stud is at an angle so don't get impatient! Work the pieces off evenly!

[Mike D]

There they are. Ready for renewal.



These "ears" are what holds the actual electrical board to the bucket.




Use a small flat bladed screwdriver to gently pry the ears past their "hook" on the board. Gently apply pressure forcing the board away from the bucket for each ear. I find it's easiest to loosen the ends and then work on the center.



Go drop the bucket and circuit board into some warm, sudsy water to soak. Do NOT use spray cleaners such as, carb cleaner, gunk or any harsh chemical. Simple Green or it's ilk is fine but honestly, dishwater soap in the sink or a pail works best and you have a handy little wash basin for your hands. Clean the board with a soft brush and give the electrical contacts a mild scrubbing with a toothbrush or fingernail brush. No metal bristles or cleaning pads. Those metal traces are some soft solder impregnated composite which is easily broken. You're cleaning it not scouring it!

This little pin is the cause of your loose bulbs.



It consists of a metal spring and the actual brass contact beneath it. It is simply a rivet connecting the spring, contact and trace together. Use a small point to clean any corrosion around the rivet head.

[Mike D]

Get the trusty ohmmeter out and check all your contacts and traces. Look for lines/cracks running perpendicular to the trace's routes. These signify breaks in the traces which will have to be dealt with even though you have continuity at the moment. There are none in this one but I'll show you what to do in my next group of posts regarding "repairs" as opposed to "renewal".



Using a steel or plastic brush, GENTLY clean the sockets of any corrosion or deposits. The sockets are made of the same mystery composite (possibly some type of aluminum powder pressure cast?) and do NOT in fact provide the ground or Earth for the lighting circuit. The lugs on the bulbs do this function and the socket walls are grounds/earths by circumstance. Use a knife blade to clean any corrosion on the copper lugs.



This is the rivet you need to make sure is holding the spring, contact and trace together. If you can, and you will be able to, wiggle the spring sideways you need to resecure the rivet.



Use a flat piece of metal as an anvil beneath the bulb side of the board. Wood or plastic won't work. It needs to be a non-shock absorbing material. A vise will do. Just be careful not to "bind" and crack the board. I use a "dolley" from my bodyworking tools. When you've restored as many old piles of junk as I have you own all kinds of neat "useless" tools.



Give the head of the rivet a few easy raps with a flat faced hammer. Check the spring for movement, re-ohm test the circuit and do the other rivets. Usually only one of the "tail light" sockets are used. The other probably is for an "euro" option we don't have here.

[Mike D]

Remember what I said about WD-40? This is what happens when some well meaning individual uses it to "clean" up those sockets. The highly reflective powder coat just separates from the plastic and flakes away. Nothing to do for this one but clean and paint it.



A couple coats of a good metallic silver. I haven't tried the Krylon Chrome yet but you might give it a try.



Put the bulbs back in their sockets, connect the harness and do a quick check of your work.



Disconnect the harness and remove the bulbs. Install the board into the bucket. There is an "ear" which fits into a receptacle in the bucket. Slip the ear into place and then lie the board into place.



Using the small screwdriver in the slots as you did for removal, apply GENTLE pressure to the board and seat the ears into place. Going from the center out seems to work the best.

[Mike D]

Almost done. If you have a pre '74 then slip the reflector into the chrome trim. The "outer" (turn signal) part of the reflector needs to go in first.



Slide the bucket onto the mounting studs. Don't forget about the oddball angle on the lower outside stud. Use a little die-electric grease on the bulbs and harness connectors. Replace the gasket. Re-install the unit using some Never-seize on the mounting studs.

Ain't that pretty?



Make sure you use the proper wattage bulbs! 5 watt or #67's for the tail lights, 21 watts or #1156 for the turn and directionals. The back-up light varies from unit to unit. If you have the metal divider then it calls for a 21 watter. Plastic calls for a 15 watt.

My next series will show you why you should only use the proper wattage.

[MAKDUFF3]

Awesome write up. also one trick we used for renewing the reflectors is using Mylar tape or sticker material like what they wrap car and trailers with. it is 99% reflective and if you use a hair dryer or the low setting on a heat gun you can fit all of the contours very well.

[Mike D]

Thanks for the tip on Mylar. I'll try that on the next set I do which, unfortunately, will be in the near future as my '74's lenses need to be done.

[MAKDUFF3]

Originally Posted by Mike D

Thanks for the tip on Mylar. I'll try that on the next set I do which, unfortunately, will be in the near future as my '74's lenses need to be done.

The first one is always a mess in almost anything until you get the tech. down.

Best of luck, let us see the finished product! gotta keep these cars on the road,

MikeD>

[skalie]

Originally Posted by Mike D

Get the trusty ohmmeter out and check all your contacts and traces. Look for lines/cracks running perpendicular to the trace's routes. These signify breaks in the traces which will have to be dealt with even though you have continuity at the moment. There are none in this one but I'll show you what to do in my next group of posts regarding "repairs" as opposed to "renewal".

After spending far too long renovating a set of tail lights, fashioning thread holders from old screwdriver handles and glue, for example, one light failed on the final test.

Turns out that one of the traces has a crack in it.

What is the proper procedure to repair such a crack ? Can it be soldered ?

Apologies if this has been covered already, couldn't find a " repair " thread, and many thanks to the original poster for this tutorial.

[skalie]

Originally Posted by skalie

What is the proper procedure to repair such a crack ? Can it be soldered ?

Appeared that the crack in the trace was next to one of the " rivets " along the line, the " board " was surprisingly resilient to heat / soldering, but no way was the solder catching, would need " mini welding " if that's a thing.

..... but, managed a fix ! Drilled a one millimeter hole and managed to screw in a tiny gold coloured metal bolt between the trace and the rivet. ( see pic )

This will keep me up and running till I manage to source some decent replacements.

Side note, there was a recommendation about to use 5W lamps for the tail light ( 3 times 21W for the reverse, indicator and brake lights ), but on the reflectors I have ( ribbed version ) there is " 10W 6CP " stamped on the plastic, so going for that.