Electrical issues

Discussion in 'Technical' started by forrest34, Sep 20, 2019.

  1. forrest34

    forrest34 Member

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    I have been having a few electrical problems for the past little while.

    First about 1 year ago I replaced the fuel sending unit. I tested the unit and the wiring to the gauge by connecting the two sides of the wire at the tank together. It still never worked when hooked up. Sometimes it moves from super empty to about 1/8th tank.

    Recently things have gotten worse. The lights behind the dash to show the gauges at night don't turn on and only the red oil light turns on before ignition.

    The dome light now works sparatically when the door is opened.

    My thoughts are a ground somewhere is not right. Where would this ground be?
    Or
    What else should I try?
     
  2. Krazy Comet

    Krazy Comet Tom

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    If it's a ground problem,will be three different ones.

    Assuming gauge read full with wires connected at tank, problem is with sending unit.

    Plug on rear of cluster can cause dash light problems as can the head light switch or fuse. Try turning dimmer back and forth about a dozen times, often the resistor has corrosion.

    Dome light problem is probably a flaky door switch.
     
  3. forrest34

    forrest34 Member

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    It does read passed fulls when the wires by tank are connected.

    How do I fix the plug problem on back of cluster? Clean connections?

    Tried the moving the switch thing a bunch and no light at all.

    Door switch just needs to be replaced if bad?
     
  4. 71gold

    71gold Frank Cooper Supporting Member

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    the plug to firewall connection and the ignition switch plug have been a lot of my electricial problems. they are my first go to checks. when I did the Ron Francis wiring kit it did away with the firewall plug...:thumbs2:
    not saying this is your problem, just sharing.
     
  5. jasonwthompson

    jasonwthompson Member

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    Does the dome light work with either door, only one door, or not at all. Does it work when you try to turn it on from the headlight switch?
     
  6. forrest34

    forrest34 Member

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    Driver's door sometimes.. I don't know how to turn it on with the headlight switch... Huh.. always works with passenger so far. Just spent a couple minutes messing with the driver's door switch if I jiggle it just right it so I guess it is the switch right?
     
  7. mojo

    mojo "Everett"- Senior Citizen Supporting Member

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    I say, probably switch. IIRC, I replaced my switches w/ one from one of the Mustang vendors. I think my problem was, dome not going off.
     
  8. jasonwthompson

    jasonwthompson Member

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    Turn the headlight switch knob counter clockwise. When it stops, turn it a bit more and you will feel it click. That click should turn on the dome light. It sounds like it may just be the driver door switch. Swap it out with the passenger side and see if the problem moves with the switch.
     
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  9. forrest34

    forrest34 Member

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    There is no power in the yellow wire at the plug on the cluster. That is for the instrument light from the headlight switch right?

    If that's the case it is probably a bad connection at the switch right?

    Also I checked por power with a power tester with a lightbulb at the gas tank. It flashes so there is no problem from the widest to the dash. Looks like I put the fuel sending unit in so it can't move to give a reading... Guess I will have to guess when I am almost on an empty tank for that fix.
     
  10. forrest34

    forrest34 Member

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    Well replaced the headlight switch. Didn't fix the dash light issue.
     
  11. jasonwthompson

    jasonwthompson Member

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    If you have been playing around with the switch, check the fuse. I believe there is one specifically for the instrument lights. It is the shortest one in the panel.
     
  12. forrest34

    forrest34 Member

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    Will do. It is really annoying to get to. Any ticks to get to the fuses easier?
     

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