Converting Fiber Optics to LEDs
A common feature on GM 1980s-1990s luxury cars was a fiber-optics alert system that would display on your fender whether your lights, high-beams, or turn signals were on. This is a reliable system that usually works fine nearly-forever, however over the course of the last 30 years many cars have had these systems destroyed by people breaking the fiber optic lines when servicing the car or by painting over the fender-mounted alert pod. Converting to LEDs is a relatively easy way to get these "dead" units functional again after they have been painted over or broken. Another advantage to LEDs is that they are several times brighter, making it easier to use this feature during the daylight.
The first thing you need to do is remove the fender-mounted pod from the fender by gently prying upward with it. If you are not careful this may damage the paint or ding the fender.
Once the fiber-optic display is removed from the fender, it disassembles into: a housing, a plastic lens, a rubber grommet that holds the ends of the fiber optics, and a gasket that goes between the housing and the top of your fender.
You need to pull the fiber optic lines from the grommet using a pair of plyiers. Be very careful because fiber optics are made out of glass and can seriously cut you. Once they are pulled out, usually a tiny metal retaining clip is left behind inside each fiber-optic "hole" in the grommet. These must be pulled out from behind using small needle nose pliers.
Once that is completed you can push a standard sized ultra-bright LED into each of the three fiber optic grommet holes from behind. Depending on where you purchased your LEDs they may have color coded wiring (red for +12v, black for ground) or if unwired one pin wil be longer than the other. In the later case, the longer pin gets connected to positive voltage and the shorter pin to ground.
LEDs, like other diodes, only pass electricity in one direction like a one-way valve, and therefor if you accidentally wire them up backwards all that will happen is that they will not turn on. Reversing the wires again will "fix" them and allow them to work.
LEDs come in a variety of colors, so it is up to you to decide what you want to use. If you wanted to mimick the original GM color-codes you will need an amber, green , and blue LED for each side. The amber you will tie to your turn signal on that side, the blue to your highbeams, and your green to your headlights.
Alternatively you could use all amber colors and have all 3 on each side tied to your turn signal.
Regardless, the general idea here is that the ground side of all the LEDs gets wired together and then run to chassis ground in a convienant location such as a fender retaining bolt or the negative side of your battery. The positive side goes to whichever light bulb you are trying to cordinate the LED with.
Reusing the clear plastic lense is optional, but if you reuse it you will probably have to cut & file off the 3 nubs that protrode from the rear-side of the lense.
Then you may choose to use silicone or some other removable epoxy to tab the rear side of the grommet to help hold the LEDs in position.
If you find that this modification causes your blinkers to act strangely, you will need to replace your turn signal flasher-relay with a solid state model (costs aproximately $10-20 depending on source).
Here is an example of this modification in action: