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The Corvette fiberoptics systems use fine clear plastic fibers bundled together in a "wire" to direct light from the turn signals, head lights etc., to the plastic lenses in your console. Things that can cause them to stop working are:
1) someone has damaged the bundle of fiberoptic cables in your front and rear wiring harnessess. The fiber optic harnessess are available through Lectric Limited and don't require replacement of the entire wiring harness.
2) The lenses in your signal light recepticles are dirty or mis-aimed so that they are not picking up the light from the light bulbs in your signal lights.
3) The harness and the individual ends have been pulled loose from the lenses inside your console.
4) None of your signal lights are working and the fiberoptics are fine .
I'm surprized that all of your fiberoptics don't work as there are separate harnesses for front and rear. It's common for a fiberoptic "wire" to get cut or damaged or even for the entire harness to get cut. If you need to just repair one of the fiberoptic "wires" you can align the two cut ends and butt them together without overlapping fibers and use heatshrink tubing to hold the ends together.
A fiber optic cable is just a very thin piece of glass wrapped in a protective coating. There is a lens at one end that fits into your headlight housing. The light from your headlight travels up the glass rod to the display in the console. Another lens is in the console and displays the light.
If they don't work, you one of two problems:
First make sure both ends of the cable are connected. If they are not, they will not work.
Second the glass rod could be broken inside the cable. If the rod breaks, it is un-repairable and must be replaced. Most of the parts vendors sell replacement cables.
You can repair fiber optic cables that has been cut or broken by using a 1/8" compression union.
Trim the ends so there are no frayed ends. You may need to wrap some tap on the ends of the cables to act as a bushing. Keep the wraps even. If you use three wraps on one, then use the same on the other. Then, feed the ends of the cables into the fitting until there is about 1/16" space separating them so that the ends are facing each other. You do not want the fibers to overlap each other. One cable must be able to "see" the light coming from the end of the other cable. Now tighten up the compression fitting a little at a time while trying to move the cables in and out of the fitting.
When you have it just tight enough that the cables no longer move in or out wrap the entire assemblage in three layers of electrical tape. Start two inches to one side of the fitting and wrap until you get to two inches on the other side. The fitting holds the cables in as perfect alignment as you're going to get. The three wraps of electrical tape keep them there.
...acually two of the front ones are working but look dim....
Dim usually means dirty. Try cleaning the ends and lenses and see if the light value doesn't improve. Clean the lenses in the console, too. They get dirty.
Dim usually means dirty. Try cleaning the ends and lenses and see if the light value doesn't improve. Clean the lenses in the console, too. They get dirty.
Also, a pinched cable can cause a dim indicator.
I pinched one of my rear FO lines between the frame and a frame bracket & tightened it down good & tight. It smushed the line and the indicator stopped working. I was able to "un-smush" it just enough so it works at about 80%.
One thing with the rear lights that will also get you is if some repainted the car and only took the lenses out of the tail light housings. I have seen the fiber optic recepticles painted over which then does not allow the light from the bulbs to pass.
Your 70's original headlights, both low beam and high beam, were manufactured with clear **** at the rear center of the headlight. A black plastic tube about an inch long fitted over the tit of each headlight and the fiber optic fitted in the end of the black tube. Fiber optics are great for monitoring the light functions so you don't get a ticket for having one burn out and not finding out about it until you get pulled over.