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1985 Eldorado Biarritz Convertible, Sable Black, HT4100
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Discussion Starter #1 (Edited)
Hi guys,
Today I decided to try and fix my fiber optic indicators in the front. When I was a kid I thought they were really cool, so I want them to work. They're in a line on both sides showing turn signal, low beams and then high beams, farthest forward. All cables were still connected to the fender mounts/indicators, but several cables were just hanging free near the lamps. Cleaned the tips with alcohol, then tested by shining a flashlight into the tips. All seemed to work and light up the indicators in the fender.

All were disconnected on the right side. First was a turn signal cable, which has a rubber hood at the end. Plugged it in, boom, it works great. However, the low and high beam indicators did not work, even though shining a flashlight into them did work and illuminate the indicators.

Fiber optics slide into the middle of the headlight wiring harnesses. The headlight glass has a little nub at the back, with a very short rubber tube that fits over it. With the headlight connector/harness on, that rubber tube pushes tight onto the harness where the fiber optic ends, theoretically creating a tube that guides light into the fiber optic. It seems like it should work, but it doesn't.

Can't figure it out. Any ideas? Has headlight design changed perhaps, and they no longer support fiber optics? Perhaps that glass nub doesn't collect light for fiber optics like they did in 1985?

Thanks
 

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White Diamond '03 DHS (with DTS floor shift)
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Is that nipple on the back of the headlamp clean and paint free?
 

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1985 Eldorado Biarritz Convertible, Sable Black, HT4100
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Discussion Starter #3
Yes, 90% sure, and it did seem to collect some light when I removed the rubber tube and turned on the lights. In fact, the indicator seemed to work better without the tube. But the tube was totally clean inside, no obstruction.

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Should the rubber tube have a reflective lining?
 

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1985 Eldorado Biarritz Convertible, Sable Black, HT4100
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Discussion Starter #4
Found some helpful info here: http://forums.cadillaclasalleclub.org/index.php?topic=106415.0

I think it's the headlights. Even with the glass nipples at back, I assume certain headlight designs might not gather/direct enough light backward. For example, my left high beam indicator works and is set up exactly the same way as the right high beam one, but the right doesn't work. I'll bet they're different brands or models.
 

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1926 Model T street rod, 2000 Jaguar XJ8, 1999 Corvette.
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6,737 Posts
Tell us if the left pair of headlights match the brand on the other side. I'm thinking the nub is not transparent, or the fiber optic cable is not butted up tight against the back of the bulb.
 

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1985 Eldorado Biarritz Convertible, Sable Black, HT4100
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Discussion Starter #7
Okay, to recap, both blinker indicators illuminate fine and only one of the headlights, the left high beam, i.e. center left, lights the fiber optic indicator. That's a Wagner Halogen "1A1" (1A1 is the lens type, right)?

Other high beam, center right, is also a Wagner Halogen "1A1". Seems exactly the same but doesn't illuminate the indicator. Low beam left is a Wagner Halogen "2A1." Low beam right has no meaningful markings beyond "GUIDE" "2A1" (the bulb type?) "SEALED BEAM" and "HALOGEN". No brand at all. No markings at the back, except "B300" on the glass, which theoretically could be a Dodge Van, but can't find anything else.

All headlights have a glass nipple at the back that seems to collect light when checked with the hose piece removed and headlights on, and all indicators light up when I shine a flashlight into the ends of the fiber optics. I'm at a loss, and I don't think any of this helps. But I wanted to update anyway.

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I'll pull all of the headlights tomorrow, see if I can determine exact model numbers, and plug the working high beam headlight in all harnesses to test their fiber optics, then report back.
 

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1926 Model T street rod, 2000 Jaguar XJ8, 1999 Corvette.
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"Guide" is the brand. That's an original headlight from the factory. GM used Guide as their in house brand for years. If the car had the original 4 headlights they would be Halogens for low beam only and all would say Guide. Wagner is a common aftermarket brand. If all the fender lens' light up with a flashlight, then either the optic tube is too far away from the back of the lens or the nub is not translucent.
 

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1985 Eldorado Biarritz Convertible, Sable Black, HT4100
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Discussion Starter #9
Thanks Carnut. Three of the tubes were right up against the harness/fiber optic mount, and, ironically, the only headlight missing the tube is the one high beam that illuminates the indicator, the Wagner.

Turns out I made a mistake. I have Wagner high and low on the left, and Guide high and low on the right.
 

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White Diamond '03 DHS (with DTS floor shift)
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That may be your problem. If the lamp indicators work with a flashlight, it has to be lamp related.
 

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1985 Eldorado Biarritz Convertible, Sable Black, HT4100
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Discussion Starter #11
I noticed in the FSM that the diagram for headlights with fiber optic indicators have cylindrical nubs at back to illuminate the fiber optics. See image:



All the nubs on my headlights aren't cylindrical, they're like cylinders that were pinched by pliers when the glass was hot. Does anyone remember if the old headlights had truly cylindrical nubs at back? Thanks.

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And there appears to be some kind of washer around the rear nub. None of my headlights have that.

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Here's what the current rear nubs look like (though on a two-blade Wagner instead of three-blade):

 

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1926 Model T street rod, 2000 Jaguar XJ8, 1999 Corvette.
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Time to check other headlights, GE, Sylvania or other Wagners. I would think Guides would be common in wrecking yards. They're not specific to just Cad's. I would think the pinched nub would prevent light to transfer. My pet peeve is to not have mismatched headlight brands on any of my cars!
 

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White Diamond '03 DHS (with DTS floor shift)
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Being so long ago, I can't swear to it, but I think all of mine where pinched like that. That FSM drawing may not be accurate.
 

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1985 Eldorado Biarritz Convertible, Sable Black, HT4100
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Discussion Starter #14
Some headlights seem to have this roundish translucent-looking thing at the rear, which is different from the pinched bits. First is an AC Delco, second is a GE:



 

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White Diamond '03 DHS (with DTS floor shift)
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I've never seen anything like those. The pinch type is the only ones I've ever seen.
 

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1985 Eldorado Biarritz Convertible, Sable Black, HT4100
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Discussion Starter #17
Here's how the bulbs look illuminated with the hose/tube removed. First pic has no flash to show how much light it's putting out in the dark, last two have flash to compensate for the headlight light:







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Second one (Guide), which appears brighter, is the right high beam. That one doesn't illuminate the fiber optic.

Third one (Wagner) is the left high beam, which does illuminate the fiber optic.

They both seem to shoot light toward the fiber optic, but only one works.

Maybe the fiber optics work with the flashlight, but they are degraded, and don't work well enough to work with the headlights' indirect light.

Thought: Could I get a small LED, wire it to the blades, and put it right in the harness hole for the fiber optic?
 
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