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Technical Dim Bulb. No, not me

Discussion in 'Traditional Hot Rods' started by modagger, Apr 7, 2021.

  1. modagger
    Joined: Jul 2, 2013
    Posts: 245

    modagger
    ALLIANCE MEMBER

    0047E806-EEFD-4138-A9B5-2F300C3F601C.jpeg Greetings All!

    I need to once again drink from the well of knowledge collectively know as the H.A.M.B.

    Beautiful day here so I thought I would take the coupe for a drive. Did some preliminary checks, oil, coolant, air pressure, lights. Everything was good until the light check.

    The driver’s side headlight is dim on both high and low beam. First thing was to swap headlamps. Trouble stayed on driver’s side. Also, the signal lamp is not as bright as the passenger side. Swapped signal bulbs, same.

    Checked for ground, solid.
    Checked for 12 volts both on high and low beam. Good
    Swapped headlamp plugs. Trouble stayed.
    Disconnected signal and parking wiring from harness, same.
    Ran a jumper from passenger side headlamp plug to driver’s side, same.

    Removed driver’s headlamp from socket, jumped from passenger headlamp terminals, still in socket, to bare terminals on driver’s headlamp. Both work fine.

    I’m stymied. Next step, Buckwheated?

    The signal flare is up!

    Be well and safe
    Jeff
     
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  2. Dave Mc
    Joined: Mar 8, 2011
    Posts: 2,116

    Dave Mc
    Member

    Engine grounded to frame and body ?
     
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  3. SS327
    Joined: Sep 11, 2017
    Posts: 189

    SS327

    You have a bad ground. Physically pull it apart and clean and check. Happens all the time when cars sit. Good luck.
     
  4. modagger
    Joined: Jul 2, 2013
    Posts: 245

    modagger
    ALLIANCE MEMBER

    Hi Dave

    I just checked again before responding. A good 100 point ground from engine to both.

    Thanks
    Jeff
     
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  5. G-son
    Joined: Dec 19, 2012
    Posts: 722

    G-son
    Member
    from Sweden

    Did you check the ground when the lamps were hooked up and turned on? Voltage loss due to resistance ONLY shows up when there's current flowing.
    Check the voltage ON the lamp, when turned on, not on the wires, connectors, sockets etc, measure on the actual lamp. You'll find that the voltage is low. Then you start to chase where you lose some of it.
     
  6. jaracer
    Joined: Oct 4, 2008
    Posts: 820

    jaracer
    Member

    You have high resistance in either the power or ground circuit connected to the dim lamp. Like G-son said, check the voltage at the bulb with the headlamp connected and turned on. With your voltmeter negative lead on a known good ground you should read within 0.2 volt of battery voltage at the lamp. (Example, if the battery voltage is 12.2 with the headlamps on, the voltage at the lamp should be at least 12.0.) If it reads less, you have high resistance in the power supply circuit to that lamp.

    Now connect the voltmeter positive lead to the ground lead at the lamp (lamp still connected and turned on, voltmeter negative lead still connected to a know good ground), the voltmeter should read 0.1 volt or less. If it reads more, you have high resistance in the ground side of the circuit.
     
  7. 1oldtimer
    Joined: Aug 21, 2003
    Posts: 7,886

    1oldtimer
    ALLIANCE MEMBER

    Un hook the ground on that side and run a jumper wire to the other side ground. It looks like you have the ground wire to a bucket mount bolt. Just an FYI, stainless makes a crappy ground sometimes.
     
  8. modagger
    Joined: Jul 2, 2013
    Posts: 245

    modagger
    ALLIANCE MEMBER

    G-son

    Bingo! With the lamp plugged in, the voltage drops to 7. The hunt is on!

    I’ll report back when I find something.

    Thanks
    Jeff
     
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  9. squirrel
    Joined: Sep 23, 2004
    Posts: 47,974

    squirrel
    Member

    When you found low voltage at the lamp, where were you measuring the voltage relative to? The chassis, negative battery cable, or some other point? If you were measuring the voltage across the light bulb housing and the contact, then you could still have a ground issue....
     
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  10. modagger
    Joined: Jul 2, 2013
    Posts: 245

    modagger
    ALLIANCE MEMBER

    Jaracer

    Did as instructed. The voltmeter didn’t even twitch.
     
  11. modagger
    Joined: Jul 2, 2013
    Posts: 245

    modagger
    ALLIANCE MEMBER

    ABEC88D3-9D8F-46FA-B7F2-765C606365ED.jpeg
    Well now, from one old timer to another, you have made me see the light my Brother!

    I was just about to start hunting through the wiring harness for a gremlin when I saw your post.

    Many thanks
    Jeff
     
  12. It pays to double check, and check amount. A couple of times I did continuity tests, and seemed good, but wouldn't take a load. Only one or two strands in a connector were complete giving me a circuit, but couldn't carry the current. Re-did the connections, and back to normal.
    Glad you got it working.
     
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  13. modagger
    Joined: Jul 2, 2013
    Posts: 245

    modagger
    ALLIANCE MEMBER

    Thanks to everyone for your troubleshooting tips! Couldn’t have done it without you.

    I hope this helps someone else down the line.

    Jeff
     
  14. SS327
    Joined: Sep 11, 2017
    Posts: 189

    SS327

    I’m glad you found it! I told you that it was a bad ground.
     
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  15. cfmvw
    Joined: Aug 24, 2015
    Posts: 598

    cfmvw
    Member

    Bad grounds can do weird things; my son had an OT car that would die every time he stepped on the brakes. Turned out to be a bad ground in the trunk for the brake/tail lights that would, for some reason, backfeed into the car computer and shut it down.
     
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  16. trollst
    Joined: Jan 27, 2012
    Posts: 1,975

    trollst
    ALLIANCE MEMBER

    I'm embarrassed to even admit to this story, years ago, a neighbour asked me to figure out why all the lights on the right side of his ford pickup didn't work. So....two frustrating, chase every wire I could, check every ground I could, days later, another neighbour, the dumbest one on the street comes by to see what I was doing.
    He says " did you check the bulbs?"
    Three guesses, first two don't count, turns out the bulbs had gone bad over time, I hadn't asked, or taken the time to check the bulbs, but I learned something that day.
     
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  17. modagger
    Joined: Jul 2, 2013
    Posts: 245

    modagger
    ALLIANCE MEMBER


    Well trollst, I’ll see you that embarrassing story, and raise you one.

    After fixing the ground problem today and putting things back together, I did some reflecting. I wondered how the ground went bad from Autumn to now. I replayed all of the things I did to the car over the Winter and, eureka! It was me.

    I put a half hood on and had to remove the radiator shell to elongate the mounting holes so the I could move it forward 1/4”.

    I had to remove the headlights to pull the wires out of the shell. So, I sez to myself, while you have all of these washers and mounting bolts out, why don’t you clean them up and paint them? Therein lies the self inflicted loss of ground.

    When I put everything back together today, I used star washers to get a good bite and a good ground.

    I’m sorry for inviting you guys to my fire drill today. If there is a next time, hah! of course there will be, I’ll pause to reflect a bit before I call in air support.

    Thanks again everyone

    Be well and safe
    Jeff
     
  18. SS327
    Joined: Sep 11, 2017
    Posts: 189

    SS327

    12 years at a Buick dealership in the Midwest will teach you a few things. Bulbs, grounds, sockets, switches and pinched wiring. Got screwed by them all. Now how do I get rid of this nervous twitch?
     
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  19. dana barlow
    Joined: May 30, 2006
    Posts: 4,268

    dana barlow
    Member
    from Miami Fla.
    1. Y-blocks

    Now that the lights are working great. And thats a pretty cool car your building,,,Find a set of front rims with the right off set**those are wrong, in the photos,if you were thinking about using them,they are bad scrub=set out too far/makes poor braking an steering,plus adds too darty from road bumps. Bring rim /tire in, with-in at least 1 in of norm} >king pin center line points to the road as ref. and that spot should be on or with in the tire contact patch with the road.< the way it is in photo,theres a fairly big gap from kingpin point on ground an tire patch=big scrub. Almost all the fins on drums should be covered by rim,if front is set up right.
    Yes there some guys driving cars like that,even say it drives great=No it dose not*,they don't know what a good driver feels like, an don't understand the engineering ,some defend there mistake,insted of leaarning. But its still a mistake that needs fixing.
    Hunt it up more,if what I said dose not seem to ring right in anyway. I owned my own speed shop for 40years,designed an built,an drove race cars all the time,plus hot rods.
     
    Last edited: Apr 7, 2021
  20. modagger
    Joined: Jul 2, 2013
    Posts: 245

    modagger
    ALLIANCE MEMBER

    Right you are Dana

    I made a mistake when I got those rims from a company that rhymes with “croaker”. It’s been bothering me ever since. I’ll hunt around for rims with the correct offset.

    Jeff
     
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  21. Be sure the wheels come with the rims

    Ben
     
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  22. modagger
    Joined: Jul 2, 2013
    Posts: 245

    modagger
    ALLIANCE MEMBER

    Hi Ben

    I’m not sure I understand. Are you saying to get rims and drums?

    Jeff
     
    Last edited: Apr 8, 2021
  23. woodscaper
    Joined: Feb 20, 2011
    Posts: 54

    woodscaper
    Member

    OK, I'll do it. The "rim" aka wheel hoop is what the tire is mounted on. The wheel center is what the "rim" is mounted on and can be mounted on in different locations giving you different backspacing. The "wheel" consists of the "rim" and the "wheel center" assembly.
     
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  24. Budget36
    Joined: Nov 29, 2014
    Posts: 5,839

    Budget36
    Member

    And we don’t have motors in cars...yadda, yadda, yadda...
     
  25. modagger
    Joined: Jul 2, 2013
    Posts: 245

    modagger
    ALLIANCE MEMBER

    Ah, now I understand. Is it time for me to leave, Master Po?
     
    Budget36 likes this.
  26. :p:p:p. Just messing with ya, chief.

    Ben
     
  27. modagger
    Joined: Jul 2, 2013
    Posts: 245

    modagger
    ALLIANCE MEMBER

    :p!
     

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