LED Changeover - 1970 to 1972 Skylark & GS

Discussion in 'Sparky's corner' started by knucklebusted, Jan 16, 2018.

  1. knucklebusted

    knucklebusted Well-Known Member

    Update: May 21, 2018 - Cut to the chase and find out what works in a 1970-72 GS by going to this post: http://www.v8buick.com/index.php?threads/led-lights.329221/page-2#post-2806659


    My other car has a really weak trunk light so I found some LED 194 bulbs for cheap with a good review on Amazon.


    They really made a big difference in the trunk so I'm going to use a few more to see how they work in the side markers and maybe the dash of my Buicks.

    Pictures as soon as I can trudge to the garage and swap them.
    Last edited: May 21, 2018
    Grandpas67 likes this.
  2. StagedCat

    StagedCat Platinum Level Contributor

    Im sure you know, but use the same color bulb as the lens color on side markers or tail lights....
  3. knucklebusted

    knucklebusted Well-Known Member

    They were cheap so I'm going to try them to see what happens. It can't hurt. If they don't work, I'll use them in my 12V accent lights around the landscaping.
  4. bostoncat68

    bostoncat68 Platinum Level Contributor

    That's a great deal -- curious to see how they look in the dash! Thanks for sharing...
  5. philbquick

    philbquick Founders Club Member

    I put them in the brake lights on my Tundra. Put it in one side to see the difference and the LED comes on almost a second faster then the incandescent bulb, at 60 MPH that's 88 feet.
  6. knucklebusted

    knucklebusted Well-Known Member

    I didn't even consider if they will dim! I'll have to see how that goes. As I get older, I really wish my dash lights were brighter.
    bostoncat68 likes this.
  7. philbquick

    philbquick Founders Club Member

    Yes they dim. The 1157 equivalent use the same LEDs for parking lights and brake/turn signal lights. The one terminal goes through a different current limiting resistor that changes the intensity. So the question becomes, is the resistive value of the dash dimmer in the correct range for an LED? If the demist position is too bright a series resistor may need to be added.
    bostoncat68 likes this.
  8. bostoncat68

    bostoncat68 Platinum Level Contributor

    @philbquick what version of the 1157 do you have?? Seems like there are a million versions
  9. philbquick

    philbquick Founders Club Member

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  10. knucklebusted

    knucklebusted Well-Known Member

    So, it warmed up and I swapped the front and rear corner markers for the LED white 194 bulbs. I can't tell they got any more orange but they are brighter. Pictures don't really do it justice but I think I'll order some red and amber ones any way since with 2 GS's to do, I need at least 4 of each.

    2018-01-21 14.53.55.jpg
    Brett Slater likes this.
  11. Briz

    Briz Platinum Level Contributor

    I did them throughout the int of the Riv, My daughters Accord and the F250. Overall I like the results. I have one turn signal ind on the riv that works when it wants and its a major project to get to the bulbs so I'll live with it. have 2 in the dash of the F250 that works sometimes not others and other times they blink like a strobe. Thats easy enough to get to. Just havent done it yet. Used green on the 250's turn inds in the dash and had to go back to reg bulbs a few days later as they were so bright it was blinding when I hit the turn signals.
    knucklebusted likes this.
  12. 1989GTA

    1989GTA Silver Level contributor

    For the tail lights on my 1965 Skylark I used the red Sylvania Zevo LED 1157 bulb. They are quite bright. For the front I used the amber Putco Plasma 1157 LED bulbs. They are nice and bright.
  13. knucklebusted

    knucklebusted Well-Known Member

    I have swapped in the red rear and amber front LEDs, not a lot of difference but I do think they pop more than they did with the white ones.

    Now, to find some decent 1156 for backup lights and 1157 in amber and red for turn and brake lights.

    I assume I'll have to swap flashers to get them to blink properly?
    Harlockssx likes this.
  14. knucklebusted

    knucklebusted Well-Known Member

    Well, my brake and turn signal lights didn't work. Installing one at a time, they will not flash as blinkers. As flashers they do not have enough difference between base and brighter to be usable. I tested them with a jumper wire on the battery and they are bright enough as markers and the turn is very bright but they don't work in the socket. After some testing, I discovered there is current on both terminals but when it blinks, the voltage drops on the base but is never the full battery voltage on the turn lead.

    So, the bulbs seem to work as expected when tested but the car doesn't give the voltage I'd expect. Anyone have an explanation for this or a way to resolve it? 1157 incandescents work fine so I believe it is made this way on purpose.
  15. 70skylark350

    70skylark350 Well-Known Member

    I though I read somewhere that you need to replace the flasher because the led's don't draw enough amps to operate it?
  16. knucklebusted

    knucklebusted Well-Known Member

    There are two problems here. I know about the blinker draw issue which is why I was testing with the emergency flashers as well. Generally, with the blinker they will light up but not flash like a blow bulb will show.

    The other problem is the bulbs aren't getting full 12 volt when using the emergency flashers. The voltage fluctuates in the flasher circuit between 10-8V, never 0-12V so the LED doesn't respond well. I suppose that voltage drop is sufficient for the incandescent bulbs but not LEDs. Maybe it is an isolation issue. I know when I test the LED bulb with the base and blinker circuits on the battery they are brighter and much brighter but in the socket they are not getting full voltage and the ground is good. It is almost like I'm getting back voltage from the two different circuits that is causing an issue and I'm only getting the difference in voltages. For instance, 12V on both would yield a difference of 0V. Could it be using them as a partial ground or something? Being an LED, voltage will not flow the other direction like it would in a filament bulb.
  17. bostoncat68

    bostoncat68 Platinum Level Contributor

    @knucklebusted this has been an interesting thread. It seems to me that the most likely cause of the voltage drop is corrosion in a splice, snap connector or the socket(s). This could be on either the + or negative side. If you increase resistance voltage can drop. On my CAT there is a snap connector for the rear wiring harness in the trunk on the driver side it's tucked up the side near the trunk opening. I would pull the harness down and pop open the connector 1) I would check the voltage there and 2) I would use some contact cleaner to get some of the tarnish off the brass contacts. You can establish a separate gound here and isolate the rest of the hardness and sockets. Lastly, I suppose that the relay itself could be the source of the drop... that seems unlikely but not impossible as all of the wiring is old. Over time the resistance on those contacts could also increase... Wonder what the voltage is when you exit the relay??? Will keep watching...
  18. knucklebusted

    knucklebusted Well-Known Member

    When you say relay, do you mean the actual flasher module? I think I could rig up a test loom with some wire so I can tap into the flasher line before and after it. I should just go ahead and buy an electronic one and see what it does. They are about $10. I've been unbolting things, cleaning grounds, using a pick to make the socket contacts higher, etc. I'm only doing this on battery since I won't start it in the garage.

    I just order another $50 worth of LED bulbs, some festoon ones for the rear sail panel courtesy lights and small ones for the under hood, trunk, license plate and two kick panel lights. Straight replacements with no flasher/blinker issues.

    The 1971 I'm want to leave alone, no major mods that aren't require. Now the 1970 I might try a bit more creative solutions to see what happens. I might run some jumper wires around the old wiring to see if that helps out at all.

    This would have been so much easier if they didn't rely on the body/frame for the ground circuit.
  19. bostoncat68

    bostoncat68 Platinum Level Contributor

    Yes @knucklebusted the flasher. On most old cars (inside the little tin cylinder) it's a little strip of bi-metal that heats and cools to open and close the circuit. Pretty simple metal on metal switch. I just wonder if the contacts inside it could get a little corroded over time -- reducing the current flow to the wiring harness. I'm just trying to think of places where you could get hidden corrosion. I know with dim headlights the headlight switch contacts can degrade over time - causing the same kind of behavior. Some folks on the board will cringe but I had a tail light socket that was an absolute mess of rust - hopeless. I soaked it in white vinegar for a week (used an old cottage cheese container - white vinegar eats the rust) then hit it with contact cleaner. It came back to life. I hear you on the ground - I hate when I sit there and scratch my head going -- why doesn't this work?? -- only to realize I'm holding something in my hand -- so there's no ground!
  20. knucklebusted

    knucklebusted Well-Known Member

    On another note, these 1156 backup light bulbs are very bright white if anyone needs some:


    Haha, I've used the white vinegar trick for years. I will salvage anything if there is metal left to salvage.

    As for the ground, I've got a couple of alligator clipped leads to ground things while I work on them.

    I wonder if I can short the flasher as in remove it and install a jumper lead to make the lights come up without flashing to see how bright they are with out the flasher to drop voltage. After all, that flasher is some kind of resistance to cause the metal to get hot and flop off.

    Good ideas! I'll dig a bit more as I have time. I'm just trying to reduce the load, improve the lights and be able to see inside the car better with my aging eyes. I had to fix the door jamb switch I broke trying to repair the under dash lights the previous owner installed. He tapped into the wire at the drivers jamb switch even though there is already a wiring harness plug for under dash lights. He ran a pair of wires all the way over to the passenger side where, as you know, there is another under dash harness plug.
    bostoncat68 likes this.

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