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Thread: LED conversion is not going well...........

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    LED conversion is not going well...........

    First I want to thank Edward B for trying to help troubleshoot my LED conversion issue. Let me start by saying that my lights currently work fine in every way. I just figured I would simply change out my bulbs and flashers and all would be fine. Not the case....... let me add that I am using a Lucas single pole switch with diodes. I think that might be important? Anyway, here is the issue. As soon as I switch out my lights to LED, anytime I put my flashers on the odometer light starts to flash along with the flashers. The more LEDs, the brighter the odometer light flashes. At that point in fact all the turn signal lights start to flash (not headlamps). The lights seem to be back fed once I change to the LEDs.........that’s why I’m bringing up the diodes. They work with the incandescent setup but it does not seem to stop the LED lights from back feeding? I could be way off with my thinking but either way it’s not working correctly. I’m back to my incandescent setup and all works flawless..... but the LED, I need some insight. Will call company tomorrow as they might have an idea......... any ideas here are welcome too of course.
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    Well Used Member boat737's Avatar
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    The diodes may be a factor, but start with this. LED's are polarity sensitive. They work only when wired up with +12V on the proper pole, and ground on the proper pole. So make sure your sockets are wired properly. Also, work with only one socket at a time and see if you can eliminate any of those as being correct, or as being a problem.
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    Sockets are all good, Black to black on each connection.
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    I could be wrong, but it seems that your backfeeding and circuit crossing is all in that odometer light. These should not be interconnected anywhere. The fact that you add more LED's and the odometer gets brighter means the increased resistance in the LED circuit is driving more power through the odometer light. Somewhere, that light is shorting to the turn signal circuit. Gotta chase those wires and find out why the odometer is in that circuit.

    Backfeed shows up with LEDs because of the much, much lower resistance makes it easier for more power to find other paths. The incandescent lamps use up enough power so there's none left for the crossover in the odometer light.

    Thought comes to mind... are you using one of those Speedhut speedometers with the internal turn signal indicators?

    The single pole switch with diodes should work fine once the backfeed is fixed. The 4 way flasher switch shouldn't have any.

    I've converted lots of bikes to full LED, my 87GT is full LED and my roadster is built as full LED.
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    Senior Member edwardb's Avatar
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    Thought about this some more after our conversation last night. Interesting observation that the lower resistance of the LED's is allowing a resistance path that the incandescent bulbs don't. Clearly your circuit is backfeeding, as we discussed. I've had this before too. Mine happened when I was trying to hook up a headlight warning buzzer that also was supposed to buzz when the turn signals flashed. It was crazy how the seemingly random circuits showed up when the turn signals were turned on. Including my dash lights that started flashing. Try this: Pull the wires off the single pole hazard switch. At the very least, the pink hazard flasher feed wire. Now try with all LED's. That location, with the installed diodes, is one possible source. How you have the turn signal indicators in the speedo wired is another possibility, and could explain the interaction to the speedo indicator panel.
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    I’m not using any of the internal turn signal lights in the gauge by the way. Those wires have been taped off. I have set up turn signal led lights on my dash. When the turn signals are turned on they all flash, not as bright as the actual signal light but they flash along with the odometer light.

    You mentioned no diode on the single pole hazard? I have the diodes on there as that’s my hazards switch. My turn signal lights are wired to the Russ Thompson turn signal assembly......

    I have that 12v red wire also coming back to the odometer so the GPS aquires the signal faster. Just want to paint a better picture of my setup.

    35DFE6EE-827D-4270-AD88-EB52ABC4B258.jpg

    There is a diode on each the blue and green wire that come off the bottom leg of the hazard switch.
    Last edited by stevant; 11-20-2018 at 07:45 AM.
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    Boydster's Avatar
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    Quote Originally Posted by stevant View Post
    You mentioned no diode on the single pole hazard? I have the diodes on there as my turn signal lights are wired to the Russ Thompson turn signal assembly......
    I have zero experience or knowledge with the RT turn signal assembly. If you have the diodes on the hazard switch but not the RT switch, thats OK. Depends on how its wired. I've always put the diodes near the TS switch, but it shouldn't matter in this case.

    Paul has experience with the RT Turn signal and LED's, so I'm going to drop out and let him help ya.

    Quote Originally Posted by stevant View Post
    When the turn signals are turned on they all flash, not as bright as the actual signal light but they flash along with the odometer light.
    All indications of that classic backfeed.
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    Administrator 65 Cobra Dude's Avatar
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    Let me ask a stupid question - are you sure the diodes are going in the right direction? The arrow should be pointing in the direction you want voltage to flow. Sounds to me like one diode is going the wrong way.

    Henry

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    Thanks.......... I’d like to go LED. It all works great with the incandescent setup. No issues whatsoever. Now with less consumption going to power the LED’s the additional power is making it back into the harness back feeding the lights.

    Bang your head!!!
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    Boydster's Avatar
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    Quote Originally Posted by edwardb View Post
    Interesting observation that the lower resistance of the LED's is allowing a resistance path that the incandescent bulbs don't.
    The way I understand this: the lower resistance means lower power consumption... a given. But with the lower power consumption, there is more power available to other parallel circuits. Incandescents consume more power, so there's no lighting of other parallels. Ran into this a lot with bikes that use a single TS indicator with no diodes.... it got its ground through the opposite side TS lights. Anyways, I could write a very large book on what I dont know... I'm sure you can help him out.
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    I’m sure I installed them correctly as one side has a silver stripe around it. I’m pretty sure that side on both wires is going towards the switch. They are both the same direction, I know that.
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    Quote Originally Posted by 65 Cobra Dude View Post
    Let me ask a stupid question - are you sure the diodes are going in the right direction? The arrow should be pointing in the direction you want voltage to flow. Sounds to me like one diode is going the wrong way.

    Henry
    Would that not show it’s ugly face even with the incandescent setup?
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    Quote Originally Posted by stevant View Post
    I’m not using any of the internal turn signal lights in the gauge by the way. Those wires have been taped off. I have set up turn signal led lights on my dash. When the turn signals are turned on they all flash, not as bright as the actual signal light but they flash along with the odometer light.

    You mentioned no diode on the single pole hazard? I have the diodes on there as that’s my hazards switch. My turn signal lights are wired to the Russ Thompson turn signal assembly......

    I have that 12v red wire also coming back to the odometer so the GPS aquires the signal faster. Just want to paint a better picture of my setup.

    35DFE6EE-827D-4270-AD88-EB52ABC4B258.jpg

    There is a diode on each the blue and green wire that come off the bottom leg of the hazard switch.
    If that question is meant for me, yes I know you have the diodes installed. And yes having the bands on the diodes toward the switch is correct. And yes if not installed properly they would backfeed on the indandescents as well. In theory anyway. By unplugging the hazard wires, takes that possible source of backfeeding out of the circuit. Tracing this stuff down often is a matter of testing and eliminating until you find what turns the problem on and off. Lots of us have gone all LED on these builds and it works. Don't give up.
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    I have the RT turn signal set up on my Coupe and ran into similar issues. I have an early Gen 3 coupe but for whatever reason it came with the old style back lights, all the new ones are LED. I have LED's in my side mirrors and the front turn indicators are also FFR LED's. It all works with normal bulbs in the back including the flash to pass with LED headlights. If I put LED bulbs in the back the turn signals and 4 way flashers stop working with both the kit flashers and the LED ones I bought. I cut my losses and put the standard bulbs in the back but kept the LED brake lights. The extra LED bulbs are going into the brake lights on the Cobra. I was surprised the LED's and regular bulbs are about the same brightness.
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    Well Used Member boat737's Avatar
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    Something else to consider. Diodes are not a "perfect" one way conduit. There is a minute about of current that can leak through in the wrong direction. As I understand it, the larger-capacity diode, the more leakage. On a circuit like a motor or incandescent bulb, it's negligible and not an issue. But an LED doesn't use or need very much power at all, so maybe the leakage is an issue. Maybe? You electrical engineers out there, this is where you chime in.
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    Senior Member FF33rod's Avatar
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    While the statement on leakage current is true, for the size of diodes we use and relative to the current needed by the LEDs, it is negligible. To clear up another misleading statement further above. Higher resistance gives lower current, lower resistance gives higher current current= voltage ÷ resistance
    Steve

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    Senior Member edwardb's Avatar
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    Quote Originally Posted by FF33rod View Post
    While the statement on leakage current is true, for the size of diodes we use and relative to the current needed by the LEDs, it is negligible. To clear up another misleading statement further above. Higher resistance gives lower current, lower resistance gives higher current current= voltage ÷ resistance
    Steve
    There you go bringing up Ohm's Law. It's a lot more fun when we're just guessing.
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    Ohm’s law? Is that a TV show?

    I’m going to pull off the pink wire on the hazard switch and see what happens. Will keep you posted!!!
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    Senior Member Fixit's Avatar
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    ohmslaw.jpg Ok guys... y'all started it.
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    Quote Originally Posted by stevant View Post
    Ohm’s law? Is that a TV show?

    I’m going to pull off the pink wire on the hazard switch and see what happens. Will keep you posted!!!
    So pulling of the pink wire from the Hazards just prevents power from going to the Hazards, but the other side with the diodes is still together. I switch on my turn signals and the same thing is happening. Odometer is flashing with them, in fact I hit the brake light and the odometer lights also...….all four rear lights are flashing, though the one that I'm activating with the turn signal switch is brighter.

    Put it all back to incandescent and all is fine...…….ALL!!!!! Are there any diodes needed on the Russ Thompson setup? I'm so confused with this stuff. Why does it work with one kind of light and not the other.
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    Senior Member edwardb's Avatar
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    Quote Originally Posted by stevant View Post
    So pulling of the pink wire from the Hazards just prevents power from going to the Hazards, but the other side with the diodes is still together. I switch on my turn signals and the same thing is happening. Odometer is flashing with them, in fact I hit the brake light and the odometer lights also...….all four rear lights are flashing, though the one that I'm activating with the turn signal switch is brighter.

    Put it all back to incandescent and all is fine...…….ALL!!!!! Are there any diodes needed on the Russ Thompson setup? I'm so confused with this stuff. Why does it work with one kind of light and not the other.
    Next step would be to separate the the left and right turn signal circuits from the switch and confirm something isn't up with the diodes.
    Last edited by edwardb; 11-20-2018 at 04:45 PM.
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    Senior Member FF33rod's Avatar
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    Quote Originally Posted by stevant View Post
    So pulling of the pink wire from the Hazards just prevents power from going to the Hazards, but the other side with the diodes is still together. I switch on my turn signals and the same thing is happening. Odometer is flashing with them, in fact I hit the brake light and the odometer lights also...….all four rear lights are flashing, though the one that I'm activating with the turn signal switch is brighter.

    Put it all back to incandescent and all is fine...…….ALL!!!!! Are there any diodes needed on the Russ Thompson setup? I'm so confused with this stuff. Why does it work with one kind of light and not the other.
    Wow, I don't blame you for being confused. That's like the twilight zone. I don't want to suggest a bunch of things to add to the confusion but if it were me for the next step I might start with all incandescent and just switch 1 light to LED at a time and see if the problem starts right away or with a certain set - e.g. replace left rear first, then right rear, then....

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    Senior Member Fixit's Avatar
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    Lets get these circuits laid out without all the text, and clarified...

    - Using the turn indicators in the Speedhut speedometer?
    - ANY vehicle wires connected to the three, blue w/ stripes wires coming out of the Speedo?
    - Your "outboard" turn indicator LED's... assuming they are "direct connect to 12V" - no external current limiting resistors needed?
    - What type of flashers are you using - thermal (old school) or solid state?
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    Quote Originally Posted by Fixit View Post
    Lets get these circuits laid out without all the text, and clarified...

    - Using the turn indicators in the Speedhut speedometer?
    - ANY vehicle wires connected to the three, blue w/ stripes wires coming out of the Speedo?
    - Your "outboard" turn indicator LED's... assuming they are "direct connect to 12V" - no external current limiting resistors needed?
    - What type of flashers are you using - thermal (old school) or solid state?
    -I'm not using any of the indicators in the Speedhut speedometer, all external.
    -No wires connected to any of the three wires, only wire is the power source to the red/black wire for a faster GPS signal. Also the daisy chain ground, light and the sensor wire itself.
    -Not sure if resistors would be needed for my external turn indicators as they are LED also.
    -Flashers are currently thermal as the incandescent lights are all back in, working perfectly by the way.
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    Senior Member Fixit's Avatar
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    Define "odometer light comes on"...
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    All the gauges flash with the flashers. The white back lighting.....

    Even when I step on the brake, the gauges light up. Back feeding going on somewhere with the LED lights only.

    Turn signal also flashes the dash. All four lights in the back flash too. Not as bright as the actual one that should be flashing.
    Last edited by stevant; 11-20-2018 at 08:02 PM.
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    Senior Member Fixit's Avatar
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    Ok... let me get my "Eddie Electron" hat on, and crunch this... This may get disjointed, but it's how my brain works.

    Incandescent 1157 bulbs - actually two lamps (two circuits) in one container. One filament for "park", one filament for "stop/turn" - common earth/ground. On the hot side they never meet.

    LED 1157 bulbs - These are (usually) made with one set of LED elements, with two input circuits. Input one is "park", with a higher internal resistance so the elements glow +/- 50% output. Input two is "stop/turn", with lower internal resistance so the elements glow @ 100%.

    "Eddie" will always take the path of least resistance, so when voltage is on the "stop/turn" input it will take priority and increase the output of the LED - but it can also leak across and backfeed the other input. (Am I making sense here?)

    I'll assume everything is ducky just sitting there with the parking lights on? Things go wonky when you step on the brake or engage the turn signals or flashers?

    Here's my guess.
    Your voltage backfeed is happening across the internals of the LED lamps. Then coming back on the "park" wiring, and because of the internal connections of the headlight switch it's polluting the "dash lights" circuit via the big dimmer resistor on the switch. Your gauge backlighting inverter is connected to the "dash lights" feed, and is being backfed and lighting up.

    An easy "try this fix" to verify:
    Hopefully your connections at the 4 corners of the car aren't permanent yet... I don't want you to hack up the harness behind the dash with trials...

    Install a diode (1N4001 is OK) with the cathode (banded end) pointed towards the lamp/socket/LED, in line on the "Park" wire, at each corner.
    - This will become a backflow/checkvalve from each LED lamp to the headlight switch "park" circuit
    Test this with the LEDs in place.

    If this solves the problem...

    Permanent & clean fix:
    Install a diode - in line - on each feeder leg to the front & rear of the car. (Again, cathode/band pointed towards the lights/load.)

    - On the wiring harness behind the dash, one of the big plug connectors has the "split/Tee" where the parking light voltage comes from the headlight switch and then a single wire goes to the front, and another goes to the rear.
    OR
    - You could also install these diodes at a convenient place downstream, but again on the main "park" feeder for F & R, before it splits to the corners of the car. Do this at an accessible spot, in case the diode fails and you have to get at it)

    This diode should block backfeed from the entire "park" circuit on both the front & rear feeders.

    (Having these diodes in place should not affect operation in the event a LED lamp craps out, and you have to temporarily install a traditional 1157 bulb)
    Last edited by Fixit; 11-21-2018 at 07:16 AM. Reason: clarity
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    Senior Member edwardb's Avatar
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    Quote Originally Posted by Fixit View Post
    Ok... let me get my "Eddie Electron" hat on, and crunch this... This may get disjointed, but it's how my brain works.

    Incandescent 1157 bulbs - actually two lamps (two circuits) in one container. One filament for "park", one filament for "stop/turn" - common earth/ground. On the hot side they never meet.

    LED 1157 bulbs - These are (usually) made with one set of LED elements, with two input circuits. Input one is "park", with a higher internal resistance so the elements glow +/- 50% output. Input two is "stop/turn", with lower internal resistance so the elements glow @ 100%.

    "Eddie" will always take the path of least resistance, so when voltage is on the "stop/turn" input it will take priority and increase the output of the LED - but it can also leak across and backfeed the other input. (Am I making sense here?)

    I'll assume everything is ducky just sitting there with the parking lights on? Things go wonky when you step on the brake or engage the turn signals or flashers?

    Here's my guess.
    Your voltage backfeed is happening across the internals of the LED lamps. Then coming back on the "park" wiring, and because of the internal connections of the headlight switch it's polluting the "dash lights" circuit via the big dimmer resistor on the switch. Your gauge backlighting inverter is connected to the "dash lights" feed, and is being backfed and lighting up.

    An easy "try this fix" to verify:
    Hopefully your connections at the 4 corners of the car aren't permanent yet... I don't want you to hack up the harness behind the dash with trials...

    Install a diode (1N4001 is OK) with the cathode (banded end) pointed towards the lamp/socket/LED, in line on the "Park" wire, at each corner.
    - This will become a backflow/checkvalve from each LED lamp to the headlight switch "park" circuit
    Test this with the LEDs in place.

    If this solves the problem...

    Permanent & clean fix:
    Install a diode - in line - on each feeder leg to the front & rear of the car. (Again, cathode/band pointed towards the lights/load.)

    - On the wiring harness behind the dash, one of the big plug connectors has the "split/Tee" where the parking light voltage comes from the headlight switch and then a single wire goes to the front, and another goes to the rear.
    OR
    - You could also install these diodes at a convenient place downstream, but again on the main "park" feeder for F & R, before it splits to the corners of the car. Do this at an accessible spot, in case the diode fails and you have to get at it)

    This diode should block backfeed from the entire "park" circuit on both the front & rear feeders.

    (Having these diodes in place should not affect operation in the event a LED lamp craps out, and you have to temporarily install a traditional 1157 bulb)
    Good post. All great information. But here are a couple more aspects:

    I have the exact brand 1157 compatible LED bulbs and SS flashers from the same vendor in #8674. Have worked perfectly from day Now driven two full seasons. The #8674 build has the same RF harness, Speedhut gauges, same diodes (Radio Shack 6A, 50V Rectifier Diodes #276-1661), RT turn signal assembly, and even the same exact wiring scheme for the turn signals. I've been working with Steve and provided the schematic some time ago. We've talked and worked through a number of things, and so far not found the cause. While a mis-wire is possible (anything is possible at this point...) I'm relatively confident that if something were hard mis-wired, it would fail (e.g. backfeed) with either incandescent or LED bulbs. Also, if the diodes were installed backwards, it would fail in either case.

    One or more of the LED's being defective is certainly a possibility. Although testing them one at a time all six work OK. Maybe the LED bulbs, even though from the same vendor, are sourced from a different manufacturer now two years later. Or maybe the manufacturer has made design or process changes that affect how they work electrically, e.g. different internal resistance or whatever. Right now, though, my money (although I'm betting very little at this point...) is on something is up with the installed diodes. Either one or both is defective or out of spec. The plan is to focus there when the body is back off and the wiring is more accessible.
    Last edited by edwardb; 11-21-2018 at 09:37 AM.
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  30. #29
    Senior Member Fixit's Avatar
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    Paul...
    The schematic you're referring to - is it the one supplied by RT with his turn signal assy?
    (Reason I ask is then I can follow along, I have that diagram)
    John D. - Minneapolis 'Burbs

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    Ok so Watson and Breeze, who offer an LED kit for the Roadster, use LED lights with a diode built in. That’s great news as what was discussed above will not happen unless the diode is bad. To check that you would run a continuity light across the two terminals on the light. If the continuity light does not light, then the diode is doing its job. If it lights, you have a bad diode which will cause the circuit to back feed. Great ending to a great point brought up by Fixit and my friend Tom.

    I’m going to test my lights on Monday when I get back but will be changing my diodes in the dash regardless as I feel, along with Paul, that they are the culprit.

    Will keep you all posted!!!
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  32. #31
    David aka Ducky2009 Ducky2009's Avatar
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    Since your using the Lucas single pole switch (with diodes), try disconnecting the pink wire and also disconnect AND SEPARATE the two turn signal wires from each other. This is why I used a DPDT switch, can't get feedback.
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  33. #32
    Senior Member edwardb's Avatar
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    Quote Originally Posted by Fixit View Post
    Paul...
    The schematic you're referring to - is it the one supplied by RT with his turn signal assy?
    (Reason I ask is then I can follow along, I have that diagram)
    No, not any of the schematics from RT. The schematic I'm referring to is shop notes I made during one of my early builds. Posted it in my build thread back then and a number of people have asked for it and used successfully. Nothing special at all. It's literally the same wiring as the schematic in the Ron Francis wiring instructions, with the addition of a single pole switch for the hazards and the resultant need for diodes because left and right light circuits are attached at the single pole switch. I haven't located a double pole Lucas switch. Only the single pole. So this was my solution to make it work.

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    Quote Originally Posted by Ducky2009 View Post
    Since your using the Lucas single pole switch (with diodes), try disconnecting the pink wire and also disconnect AND SEPARATE the two turn signal wires from each other. This is why I used a DPDT switch, can't get feedback.
    Im getting new diodes and once I do I’ll be separating the wires and testing like you say. I’m sure I’ll have no issues as the back feeding will be eliminated. If I still get back feeding........ other issues going on!! Hopefully the new diodes do the trick!
    Build#1: MKIV Roadster #9320

  35. #34
    Senior Member AC Bill's Avatar
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    Simple solution. Switch back to incandescent bulbs.

  36. #35
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    Quote Originally Posted by AC Bill View Post
    Simple solution. Switch back to incandescent bulbs.
    Option is still on the table.... lol!!
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    Ok, scratching my head again. I tested each bulb with a conduit light and the internal diode appears to be working. It only lights up with current going one way. So now that the lights appear fine I went ahead and disconnected the wires that shared the bottom leg of my SPST hazard switch. They currently have diodes to allow me to use that switch. Well, I’m still getting back feeding into my dash. It happens as soon as I add a 4th led into my setup. Once I change all six, the dash lights get even brighter. The dash lights at that point will flash with my turn signal, or light steady when brake is applied. So back feeding through the hazard diodes is not the issue since this is happening when completely disconnected. I changed the diodes anyway and when reconnected even the hazard flash the dash lights. Here is the part that I struggle with. Put the incandescent lights back in and all is perfect.......
    Build#1: MKIV Roadster #9320

  38. #37
    Senior Member Fixit's Avatar
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    ...the "bulbs" test OK - the internal diodes seem to check out.
    Incandescent bulbs have a huge resistance (in comparison to LED)... in comparison they are a dead short. This will shunt/pull down stray voltage.

    There's a thing about diodes - they're not a mechanical "on/off". They're rated with a specific forward & reverse voltage, and if the parameters are exceeded they will break down and allow current to pass. Your stating that as you add the 4th "lamp" to the circuit things go wonky...

    On #9365 I'm converting the front turn/park lamps into LED "switchback" DRL (daytime running light) and turn indicators. This requires a +12v, ignition switched feed to the front (only) parking light circuit. Blah, Blah, Blah... whatever I tapped into the fusebox with a switched feed and everything was ducky until I pulled the headlight switch to "Park" with everything else OFF. My gauges woke up, the IGN relay on the Coyote fusebox clicked on, and a WTF was uttered.
    This should not be happening.

    There is some loopback/sneak circuit in either the RF harness or the headlight switch (or both) that is messing with this.

    Just try inserting another diode on the main feeders to the parking lights F & R or at each lamp...
    Last edited by Fixit; 11-25-2018 at 06:49 PM.
    John D. - Minneapolis 'Burbs

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  39. #38
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    Quote Originally Posted by Fixit View Post
    ...the "bulbs" test OK - the internal diodes seem to check out.

    There's a thing about diodes - they're not a mechanical "on/off". They're rated with a specific forward & reverse voltage, and if the parameters are exceeded they will break down and allow current to pass. Your stating that as you add the 4th "lamp" to the circuit things go wonky...

    On #9365 I'm converting the front turn/park lamps into LED "switchback" DRL (daytime running light) and turn indicators. This requires a +12v, ignition switched feed to the front (only) parking light circuit. Blah, Blah, Blah... whatever I tapped into the fusebox with a switched feed and everything was ducky until I pulled the headlight switch to "Park" with everything else OFF. My gauges woke up, the IGN relay on the Coyote fusebox clicked on, and a WTF was uttered.
    This should not be happening.

    There is some loopback/sneak circuit in either the RF harness or the headlight switch (or both) that is messing with this.

    Just try inserting another diode on the main feeders to the parking lights F & R or at each lamp...
    So that would be the brown wire, main power feed, to each light front and rear, correct? I split mine to feed each of the rear lamps so I’ll place diode before the split in the rear.
    Build#1: MKIV Roadster #9320

  40. #39
    Senior Member Fixit's Avatar
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    Without going out to the shop and looking I think it's the "tan" wire... just temporary a diode (band to the load/lamp) in-line/series before it splits L & R, on each main feeder to the F & R of the car.
    John D. - Minneapolis 'Burbs

    1965 El Camino - LT-1, 4L60e, 4wh discs, SC&C susp.
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  41. #40
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    Tan wire it is.... not brown, sorry.
    Build#1: MKIV Roadster #9320

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