TAILLIGHT MODIFICATION



I am at a loss as to why the Chevrolet designers created a reflector ring around the reverse lights the same size as the stop/signal lights.  They could have made them functional, or left them off entirely.

One of the ideals I have been tossing around was to make that reflector into a functional light.  To see what it would look like, I came up with some photos:


Working stop lamps



Working turn signals

	The back of the reflector has a raised area.  This is too small to be useful as a reflector for a normal bulb, but LEDs might work out great.  The large hump in the center is for the reverse light.
	APC makes a LED replacement bulb for the 3057 stop/signal bulb.  I have not been able to find one of these locally and I may have to order it.

Why go with LEDs?  First off, they consume very little power.  The factory harness was designed for the current draw of a 3057 bulb.  If my new lights need more current than that, I could burn the harness or blow a fuse.  So if I switch the existing 3057 bulb to the APC LED one, I can reduce the current draw from that bulb and any LEDs I add should keep me below the designed load.  Other benifits: LEDs run cool, are not shock sensitive, and do not burn out.    Another option is EL (electroluminescent) wire.  I confess, there is really no good reason for considering EL wire.  However it is pretty cool stuff and I have been wanting to work with it.

My plan is to use parts from Radio Shack as much as possible.  RS tends to be expensive, but it will allow others to duplicate this project without worrying where to get parts.

My ultimate goal is to have sequential turn signals:



I searched the 'net for sequential turn signals and found a lot of devices for the '84-'86 Impalas.  However, they are rigged for three lights and my plan is for only two.  I did find another site that has a two-light unit.  However, the blink rate depended on the factory blinker unit.  If the blink rate is too fast, they recommend opening the case of the blinker switch and modifying it.  This only works on mechanical blinkers and the Impala has a electronic one.

What I ended up doing is designing my own sequential blinker circuit.  The original blinker acts as the signal input for my circuit and my circuit drives the blinkers.  The drawback to my circuit is it needs +12V to operate.  I may tap into the OnStar circuit for power.  Another source could be from the sunroof electrical connector.  Or I might just run a 12 volt line back there.

I had a setback today.  The APC LED taillight bulb will not work for this project.  First off, the APC bulb (part number 50.4050.C) does not really fit.  The base of the bulb is just a fraction too thick.  I flattened the contact wires a bit, but it's still a really tight fit and I had to really force it in there.  If it was only that, it wouldn't be an issue but there is a bigger problem.  Some LEDs glow all around.  These LEDS shine their light straight out.  This wouldn't be too bad, except the Impala bulb is actually set in the taillight housing at an angle.  So the LED bulb is casting the light sideways.  To top it off, the reason the whole taillight circle glows is because the bulb throws light all around and the reflector focuses the light backward.  The LED bulb only shines the light at one spot.  The result is this really lame dot of light.

I am going to have to re-think this

I've been playing around with some ideas for this project.  I just ordered 30 LEDs from an online company.  The are rated at 3500 mcd with a 45 degree viewing angle.  I have no idea how bright that is supposed to be, but the wide angle LED from Radio Shack is only 800 mcd with a 40 degree viewing angle.  Hopefully it will arrive by the end of the week so I can play around with it this weekend.

 Faisal installed the APC LED replacement taillight bulbs in his Impala and it burned out his whole lighting system.  It took two hours work of work and a lot of parts to fix the problem.  I'm not sure what went wrong, but now that I think about it, when I put back the regular bulb, the lighting system wouldn't work and I traced it to a blown fuse.  At the time I chocked it up to a coincidence, but now I'm not so sure.  Since the APC bulbs didn't work out anyway, I'm not going to bother researching this further.  I'll just state that using the APC LED bulbs may be questionable.