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Thread: oh ye electrical gremlin... go away (please) - RESOLVED! bad LED!

  1. #1
    25th Anniversary #9772 toadster's Avatar
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    oh ye electrical gremlin... go away (please) - RESOLVED! bad LED!

    ok - the car is (was) fully working IMHO before paint - two electrical gremlins bugging me

    1. high beams on by default - already chasing this one https://thefactoryfiveforum.com/show...-on-by-default wiring looks good, but still digging

    2. right turn signal flashes all the dash lights - yes, you read that correctly...

    using the left turn signal is just perfect, left lights blink on/off or hi/low (if lights are on), and the left indicator blinks in the speedhut speedo

    setup:

    RT Turn Signal setup
    IDIDIT relay for high/low beam on the stalk
    RF wire harness
    Speedhut wire harness
    locking hazard button

    we've pulled the lower dash/stereo out to get more room - trying 'not' to pull the dash if we don't really have to
    also took the speedometer out of the dash to see inside a bit more

    somehow we're determining that the right turn flasher is somehow tied into the dash lights - trying to trace everything

    here's the testing (over testing IMHO) on the wiring

    as would be expected if you hook up a white dash light wire to pink flash wire
    all 4 lights flash on/off - but so does the dash



    hazard light activity:
    turn the light switch on - dash lights turn on - press hazard, 4 hazards flash as expected, dash is lit (no flashing)
    turn the lights off - dash lights turn off - press hazard, 4 hazards flash and the dash flashes


    turn signal activity:
    key on, activate left turn signal, left turn signals blink, left turn signal blinks in speedo
    key on, activate rt turn signal, rt turn signals blink, rt turn signal blinks in speedo, AND all dash lights blink


    connect green left turn to pink hazard, left blinks as hazard, front right parking light goes out
    blue hzd rt connect to pink hzd flash - all 4 blink


    light switch turned on green left side turn - connect to pink hzd
    left front blinks low/hi flash, right front blinks on/off flash
    left rear blinks low/hi flash, right rear stays on low light, no flash


    light switch turned on blue right side turn - connect to pink hzd
    left front stays at low light no flash, right front does low/hi flash
    left rear stays at low light no flash, right rear does low/hi flash


    light switch turned off green left side turn - connect to pink hzd
    left front blinks on/off, right front is off
    left rear blinks on/off, right rear is off


    light switch turned off blue right side turn - connect to pink hzd
    all 4 lights flash on/off
    dash flashes with lights

    very odd how some of the corner lights flash differently depending on wire connections - obviously not fully wired as expected as the hazards are wired in pairs (front/rear, left/right) so that may be the odd blinking modes

    really perplexed that when the right turn signal is used, the dash flashes...

    I know it's a matter of tracing wires, but any first thoughts? very odd!!
    Last edited by toadster; 07-31-2024 at 09:27 AM.
    Todd
    25th Anniversary MkIV | #20 of 25 | Build #9772
    https://cobradreams.com/ <- my build!

  2. #2
    Senior Member Nigel Allen's Avatar
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    G'day Todd,
    Most of these, if not all will be grounding issues. This is particularly the case when unrelated lamps glow. It is a case of positive voltages unable to flow directly to ground, and instead finding their way to ground through other lamps, in turn causing them to glow. Check all grounding to chassis of head, tail and indicator lamps at vehicle corners. Take time to think of what might have been disturbed during prep for paint. Don't hesitate to reach out.

    Best of luck,

    Nige
    Last edited by Nigel Allen; 07-26-2024 at 05:37 AM.
    Mk.4 FFR supplied Right hand drive
    Received 12/2012 completed 12/2019
    Gen1 Coyote / TKO600 / IRS
    Lots of mods to make compliant for Australian design rules

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  4. #3
    Senior Member Nigel Allen's Avatar
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    Take the front right hand indicator lamp out of its socket and see if the dash light/ front right indicator issue goes away. From your description it would appear that right indicator and parking light circuit are shorted together. One obvious place for this to happen is in the lamp holder.

    Nige
    Mk.4 FFR supplied Right hand drive
    Received 12/2012 completed 12/2019
    Gen1 Coyote / TKO600 / IRS
    Lots of mods to make compliant for Australian design rules

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  6. #4
    Not a waxer Jeff Kleiner's Avatar
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    Wacky behavior like this is often one of two things...either a weak ground at one of the lamps which will allow current to backflow as it seeks ground OR a bulb that is clocked incorrectly in it's socket and which will allow both terminals of the bulb to touch the contacts in the socket. I'd start with the easiest path by taking bulbs out of the parking light sockets and see if that cures it.

    EDIT: After reading Nigel's comments it looks like he and I are both on the same page

    Jeff

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  8. #5
    25th Anniversary #9772 toadster's Avatar
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    thanks guys! hopefully that will be some quick testing
    Todd
    25th Anniversary MkIV | #20 of 25 | Build #9772
    https://cobradreams.com/ <- my build!

  9. #6
    Senior Member Mike.Bray's Avatar
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    Groundliness is next to Godliness.
    My build thread https://thefactoryfiveforum.com/show...Roadster-Build

    Thread on Stainless Steel AN brake lines.

    Thread on fasteners and torque wrenches.

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  11. #7
    25th Anniversary #9772 toadster's Avatar
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    Quote Originally Posted by Mike.Bray View Post
    Groundliness is next to Godliness.
    LOL yeah
    Todd
    25th Anniversary MkIV | #20 of 25 | Build #9772
    https://cobradreams.com/ <- my build!

  12. #8
    Senior Member Blitzboy54's Avatar
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    Seriously, I over grounded everything. Can’t have too many (maybe you can but I have not yet found the limit)
    Last edited by Blitzboy54; 07-26-2024 at 04:52 PM.
    Build 1 MK4 #10008 - Delivered 03/03/21, Graduated 7/20/22 - Sold 6/6/24
    Build Thread #1 https://thefactoryfiveforum.com/show...been-delivered
    Build 2 MK4 #11061- Delivered 08/24/24
    Build Thread #2 https://thefactoryfiveforum.com/show...006#post562006

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  14. #9
    Senior Member CraigS's Avatar
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    Also look at grounding bolts threaded in to the frame that may have been removed and then that area was painted. Or a light socket pulled from the body, left hanging, and got some paint into it.
    FFR MkII, 408W, Tremec TKO 500, 2015 IRS, DA QA1s, Forte front bar, APE hardtop.

  15. #10
    Senior Member CraigS's Avatar
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    Quote Originally Posted by Blitzboy54 View Post
    Seriously, I over grounded everything. Can have too many (maybe you can but I have not yet found the limit)
    I agree, decades ago I was a Lexus tech and we had a car w/ very weird auto trans shifting. Tried this and that and finally ordered a trans to be replaced under warranty. Still shifted weird. Finally found that a ground wire that bolted to the back of the intake plenum (cross wise V6 so plenum to firewall clearance was about 3/4inch) was attached but the bolt was not tight. History showed that about 4 months prior a brake line had been replaced which required removing that ground wire to get it out of the car. We were pretty sure that the bolt had been installed finger tight but the final wrench tightening (maybe one full turn) had been overlooked.
    FFR MkII, 408W, Tremec TKO 500, 2015 IRS, DA QA1s, Forte front bar, APE hardtop.

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  17. #11
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    I chased a wacky turn signal issue I was having for over a month. It ended up being the bulb like Nigel and Jeff said. Lesson learned-always start with the easiest solution first.

  18. #12
    25th Anniversary #9772 toadster's Avatar
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    pulled the front right led bulb, dash flashing goes away - doing more testing

    thanks guys!
    Todd
    25th Anniversary MkIV | #20 of 25 | Build #9772
    https://cobradreams.com/ <- my build!

  19. #13
    Senior Member Nigel Allen's Avatar
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    Try putting the left hand lamp in there, as it had been working okay.
    Mk.4 FFR supplied Right hand drive
    Received 12/2012 completed 12/2019
    Gen1 Coyote / TKO600 / IRS
    Lots of mods to make compliant for Australian design rules

  20. #14
    Not a waxer Jeff Kleiner's Avatar
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    Quote Originally Posted by toadster View Post
    pulled the front right led bulb, dash flashing goes away - doing more testing

    thanks guys!
    Put it back in clcoked correctly.

    Jeff

  21. #15
    Senior Member Mike.Bray's Avatar
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    My build thread https://thefactoryfiveforum.com/show...Roadster-Build

    Thread on Stainless Steel AN brake lines.

    Thread on fasteners and torque wrenches.

  22. #16
    25th Anniversary #9772 toadster's Avatar
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    ok - looks to be one bad LED 'upgrade' bulb that I have - one of them works, the bad one replicates issues side to side and on the dash - SO weird!

    so back to incandescent until I get a replacement...

    it's simply unbelievable - one bad bulb caused the dash to flash (depending on what side it was on), it caused my hazard light itself NOT to flash, AND it killed my horn! WTH??!

    swapped out to good bulbs and everything works perfectly!

    WOWSERS! Thanks all for your help!
    Todd
    25th Anniversary MkIV | #20 of 25 | Build #9772
    https://cobradreams.com/ <- my build!

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  24. #17
    Senior Member Nigel Allen's Avatar
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    Wow, great outcome. The horn fault has me beat.
    Mk.4 FFR supplied Right hand drive
    Received 12/2012 completed 12/2019
    Gen1 Coyote / TKO600 / IRS
    Lots of mods to make compliant for Australian design rules

  25. #18
    25th Anniversary #9772 toadster's Avatar
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    totally agree! no clue why the horn quit at the same time!
    Todd
    25th Anniversary MkIV | #20 of 25 | Build #9772
    https://cobradreams.com/ <- my build!

  26. #19
    Senior Member
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    Glad you figured it out. I was having similar strange issues and after a month of testing and researching it ended up being an LED turn signal bulb that was not turned all the way to the left. It's so frustrating when you are that close to being finished and something so minor sets you back.

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  28. #20
    Senior Member BRRT's Avatar
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    That is insane! Glad you found it.
    Nigel and Kleiner have super powers.
    ----------------------------------------------

    Jeff
    Roadster delivered 8/27/23
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