Adding Electroluminescent Coach Lamps
For All 1983-88 Cougars / Thunderbirds
Page Revised: 10 May 2019
When the aero Cougar first appeared in 1983, a few critics noted that the car had some holdovers from previous Cougars that dated the new body style, such as the stand-up hood ornament, ultra-plush LS velour interior, and the exterior coach lamps. Now here at COOL CATS we have always loved those coach lamps. And all these years later, electroluminescent coach lamps have seen a comeback with import tuners. We were definitely ahead of the trend! If you've always wanted the Cougar's coach lamps for your car, but it never came with them, this section will help you with information and installation.
The factory electroluminescent coach lamps were standard on all 1983-86 Cougar LS models, and 1983-84 base (GS) models that had them as an option. No XR7 model had them, and no post-1986 Cougar had them. Here's how they work: inside the emblem's tan-colored casing is a miniature power inverter that works off 12v. The inverter is attached to a thin electroluminescent plate via two copper bands. When lit, the plate will emit an audible hum or whine. On top of the plate is a light diffuser, which helps to distribute the light evenly, and then the top acrylic Cougar logo. The acrylic is glued to the casing from the factory. The entire assembly is held to the car via a metal retaining ring with rubber on the back to prevent water infiltration. The ring has 3 prongs on the back side, which go through the car's rear quarter panel, and attach inside with aluminum quick-nuts. The bolt pattern for the ring favors the 1983-86 cars, as the bolt pattern shrunk just enough not to make these usable directly on 1987-97 cars.
The hardest part about the EL coach lamps is actually finding them. They are not sold at Ford dealerships anymore, and NOS lamps go for big bucks on eBay when they're available, which isn't often. Used units do show up on eBay, albeit very rarely. You may have to go hunting at swap meets or the local salvage yard. Remember, there are plenty of 1983-86 LS owners that are looking to replace their burned-out lamps, so the competition will be fierce. Also don't forget that you will need the EL lamp assembly as well as the retainer (trim) rings to hold them in—both are necessary.
If you acquire a set, the first thing you MUST do is test them, so that you don't end up drilling holes in your car for nothing. The lamps invert the power off 12v DC, so usually you'd just hook up the power (brown) and ground (black) wires to a car battery to test them. However, a neat trick is to carry a 9v battery with you and test the light out on that. It won't show at full brightness but you will be able to see if it does light up at all, and you should hear the inverter hum a little. If so, you know you've got working units at least, and you're ready to install. If not, see the Troubleshooting section below.
Installing the coach lamps is not terribly difficult, although you do need to drill a hole in your perfectly good rear quarter panel to mount these lights. Start by removing your interior sail panel, remove the black insulation panel underneath it, and there you have the quick nuts for the original Cougar emblem. Remove the nuts and the emblem should just pop out; if not you may need to gently pry the emblem off the car.
Notice the two small holes that are directly opposite each other (the third hole is for the guide pin on the emblem). Find the exact center between them and make a mark. Then, using a 1" hole saw, drill the new hole. This large hole is necessary because the electro coach lamp casing has a shaft that contains the power inverter; you cannot get around this. It is usually okay if you're not exactly in the center, but you don't want the casing to touch the metal, or else the acrylic outer cover will crack with road vibrations.
You will need to apply some type of gasket on the back of the electro emblem before installation. A hand-made rubber gasket or silicone will work; even electrical putty is fine. The trick is to completely eliminate the chances of water entering the new hole you just made. Also, you may wish to treat the bare metal around the hole with paint to prevent rust. Remember that this part will not show so feel free to use anything, like touch-up paint or even nail polish. Tighten up the nuts inside the car, and the emblem is officially mounted.
Now you need to find some electrical power for the lights. From the factory, these lights required the interior reading lamps for the back sail panels, because both worked off the same wiring harness. It's impractical to find and use this harness. Your best bet is to run the wiring from the lamps to the trunk, and tap into the marker lamp (not a brake/turn signal lamp). These coach lamps require very little power so you don't have to worry about any type of power drain. The electro lamps have a simple two-wire hookup: power and ground. If you can clip the harness end and some of the wiring from a donor car, this is a plus. Otherwise you can use simple speaker clip connectors. After the wiring is completed, try them out, reassemble the interior, and you're finished.
So what happens if your lights don't work, and you're positive that the wiring is correct? Well, that's the gamble you take with old units. The problem with these lights is that they're well over 20 years old and will stop functioning sooner or later. The inverters seem to be the problem. Once they've lived their useful lives, they will no longer transfer power correctly, and the light will flicker and cut out. Also, a very loud high-pitched whine can sometimes emanate from the lamp when they're about to die. Eventually the inverter quits altogether and the lamp will no longer light up. The inverters do have a Ford part number stamped on them, but that number is obsolete and the chances of finding any older inverters laying around is slightly less than a snowball's chance in Hades. In this case you have three options:
- Live with them not working.
- Disassemble them and install a regular light bulb.
- Find a way to install a new electroluminescent plate and inverter.
(We'll assume that option 1 is not an option at all.)
Some people have gone for option 2 and have cracked open their lamps, removed the inverter and electro plate, and installed a simple Ford factory bulb holder and bulb. This is good because it's a replaceable bulb. But bulbs do not distribute light evenly, which is why they weren't used in the first place, so the electroluminescent effect is totally lost. You can try using a piece of scuffed-up Plexiglas, or even frosted Lexan, to help with light diffusing. It's about the cheapest and most practical way to keep the lamps lit, although it's not going to have the same effect.
Option 3 demands that you put a new electro plate in there. It may be possible to pirate parts from one of the newer import car electro emblems and reuse them in your coach lamps. Don't forget that technology has changed dramatically in the last 20 years—newer electro emblems have much smaller power inverters. You can also do a search on the Web for companies that sell electroluminescent lighting. This is an option that can definitely work, and will definitely get the correct look back.
Stephen has written and reported this:
"I read your part about the electroluminescent coach lights, and I have some new info for you. The newer EL stuff is available as a complete experimental kit from an electronics parts supplier, All Electronics Corp. The kits run about $24 US for a complete kit. I found them doing some research for my other hobby, rebuilding and building custom dashes and gauges. I plan to use my existing emblems on the sides to make my own EL coach lights."