Bergerboy

Hi All.
Trying to replace and/or update front bulbs to Halogens on the '69 Coupe I just brought home.
(2 Were out, and the other 2 were dim and dingy.)
I've got all four working now with Sylvania's, but can't seem to figure out the hi/low beam set-up.
I've figured out (I think) that the inner 2 are hi's and the outers are the low beams.
When I have the hi beam depressed, I'm supposed to see all four bulbs on, right? Cause that's what happens.
But when I go to low beams (regular driving), the only bulb burning is the outer left one. The right outer bulb goes out as well as the 2 hi beams.
Any clue as to what I've got going on here? Is it a wiring issue?
Seems that if both low beams worked with the hi's in High Beam mode, that the low beams would both stay on in low mode.
Thoughts??
Thanks!!
(BTW: loved my first full day as a C3 owner, tinkering most of it away in garage with the football game on the radio! - Wish I was driving though!)

vbgod1

HI beam and low beams are 2 different circuits. Check the non working bulb and make sure the 3 wire connector is on the bulb terminals. If that's good, I would check between the Black and Tan wires for power with a test light, with the lights on low. If it shows power, I would say bulb. If not, ground the test light and see if the tan has power, if not, wire is open somewhere. If it has power, hook the test light clamp to power, and check the black wire in the connector.

Bergerboy

Thanks.
Got it figured out now.
Was the bulb itself.
I guess the low-beam bulbs have 2 levels of brightness depending on if set on high or low beams. So when in high beam mode, it was working, but when switching back to low beam, the low beam bulb on one side went dark.
So, I've got all 4 new Sylvania XV Halogens wired up, and just finished up aiming them and spraying down the lift springs with some WD40 for lubrication.
Buttoned up the trim bezels and good to go.
All I need up front, is the replace one of the H/L door sensors which broke off at the plastic threaded stud, and causes the HeadLamp tell tale light to stay lit indicating the door is not fully up (I learned).
Would also like to get the H/L washer nozzles working as well as the fiber optics (where are the H/L sensors for those?), but those are likely winter projects.
Mainly want to get all the safety related stuff tackled before the winter.

Alan 71

Hi Bb,
The headlight fiber optic cable for the headlights are in center of each of the electrical connectors.
The headlamps must have a glass 'stalk' on bulb between the 2 electrical prongs.
In addition there is a small diameter rubber tube that fits in the connector and helps contain the light so it's directed from the 'stalk' to the fiber optic cable.
Pretty neat system!
Regards,
Alan

The 'tubes':


The fiber optic cable in the connector:


The connector and 'tube' in place on the headligh:

Bergerboy

Thanks Alan - Good info!
So, I didn't notice if the bulbs I bought had the glass nib in the rear of them. Are those types specific for the Corvette? Or do those nibs exist normally for sealed-beams?
Also - the connectors didn't seem to have the fiber optic cables embedded in them. The 3-prong for the low-beams had 3 electrical leads, and the hi-beams only 2. I didn't notice if the connector had a center cavity meant for the fiber optics. I believe all four bulbs are to be F.O. monitored, right?
Just received my owners manual and service manual in the mail yesterday, so I've got some homework to do first.
The F.O. system is going to be an off-season re-furb anyway. I'm mainly glad I got the lights working, and got an alternator that would keep them lit!! And I want to make sure I didn't buy the wrong bulbs that wouldn't accommodate the F.O.'s.


Thanks Again!

Alan 71

Hi Bb,
I'm still using the original headlamps.
I don't know if contemporary lamps have the 'nib' or not?
Here's one with out the little rubber tube on it.
Regards,
Alan

Bergerboy

Thanks again Alan,
So, does the F.O. cable come through the electrical connector? And on both the 3-prong low beams and the 2-prong highs?


Anyone else have input on whether modern bulbs have the glass "nib" at the back to transmit some light to the F.O. sensor?


Man- your system looks pristine!
I was contemplating replacing all the springs (one is broken and the others look grungy and tired - or maybe too stiff).
Replacement kits are pretty cheap for a set of all 8.
Is that worthwhile?
Was thinking that fresh springs may put less burden on the vacuum system to drive the doors open and close.

Alan 71

Hi Bb,
Except for the broken spring the rest can be cleaned up pretty well with a wire wheel on a bench grinder.
In the photos all the headlight mechanism pieces are original. They've just been cleaned and replated or repainted as necessary.
It's a nice job for a few saturdays when the weather is bad!
Regards,
Alan

Andredechimpansee

So what you mean is the dash is lit by fiber optic from the headlights.
My dash is very poorly lit. Thought it were fuse light bulbs. Wanted to replace them with LED when I tinkered with the rpm and speedo.
those C3 engineers had to many cutting edge new ideas, making maintenance complex to say the least

Bergerboy

Dash (gauges, etc.) has bulbs for local light.
The fiber optics light up indicator lenses in the console in front and behind the shifter for the head lights, parking lights, tail lights, and license plate light.
Pretty cool 1968 technology, but not very durable apparently.

Alan 71

Hi A,
It's not the dash per say where the fiber optic indicators are seen.
The fiber-optic lenses are located in a separate bezel for the front indicators, forward of the shift plate on the shifter console, and the lenses for the rear lamps are part of the shifter plate itself (towards the rear of the plate).
The fiber optics were standard equipment on 68-71 cars, so your 79 wouldn't have them.
Regards,
Alan

7T1vette

1968 thru 1971 had the fiber optic 'lamp detection' system. Don't know what year you have. F/O 'readout' lenses are on the lower console: headlamps/park lamps at front of console; tail lamps & license lamp at rear of console. The F/O lines transfer light from lamps that are actually lit to the lenses on the console. That way you can tell if you have a lamp burnt out [or not working] from inside the passenger compartment.

Bergerboy

I would suggest trying a new low beam bulb. Worked for me yesterday.
I believe they have a dual element so that the one that lights in low beam mode may be burned out while the high beam element is still intact.
That was my theory anyway.