Fuse

Discussion in 'General Ranchero Help' started by FrenchFan, Apr 15, 2019.

  1. FrenchFan

    FrenchFan In Overdrive SILVER MEMBER

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    594
    Location:
    Rennes / FRANCE
    Does anyone know wich fuse protect the OIL light on a non GT instruments cluster on a 75 please ?

    Thanks
    Eric


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  2. FrenchFan

    FrenchFan In Overdrive SILVER MEMBER

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    Found that draw in the owner manual, it seems that the OIL bulb isn't protected by a fuse...

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  3. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    No, it isn't. The circuit generally doesn't run the risk of damage from a short to ground.
     
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  4. Dan the ranchero man

    Dan the ranchero man MODERATOR Staff Member

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    the bulb and the sending unit would be the only things that could go bad. Also check the condition of the wire that hooks up to the sending unit. The connectors on those don't fit tight and will cause the circuit not to work. Hope this will help. take care Dan
     
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  5. FrenchFan

    FrenchFan In Overdrive SILVER MEMBER

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    Thanks Dan, the bulb is good and when i put the wire that hooks up to the sending unit directly to the ground the bulb doesn't light on, so i think i have to check the wires now.....just have to find time to :)
     
  6. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    Do you have the cluster out, still? You should check the foil runs that the bulb holder contacts (as well as make sure the contacts themselves are not bent or broken off), and clean the foil areas with a pencil eraser. Then check the connector terminals for corrosion and tightness; clean each with an eraser, then hook back up and retest.
     
  7. FrenchFan

    FrenchFan In Overdrive SILVER MEMBER

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    handy_andy, the circuit is new and just installed, i had the same issue with my old circuit. I suspect the red and yellow wire feeding the OIL bulb to be the source of the problem, i tested from the positive of the bulb on the circuit connector to the ground with the ignition key on "run"position and had no voltage at all. I'm going to test this wire, just have to follow it to find its source, i think it's located behind the fuse box...
     
  8. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    IF I remember correctly, the bulb is to have power at all times, and the sender grounds the circuit. So if you don't have power at that wire at the cluster, then yes, trace it back. It may have an in-line fuse link, or a fuse link at the starter solenoid. If I can find my '74 diagrams, I'll look it up tonight. Or, there may be diagrams here on the site.
     
  9. FrenchFan

    FrenchFan In Overdrive SILVER MEMBER

    Messages:
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    Location:
    Rennes / FRANCE
    My problem is when i turn the ignition key to the "1st position" (i think it's the run position) the ALT and OIL lights have to light on to check they are still "alive", only the ALT light is lighting on in the cluster.
    Mine is a 75 ;)
     
  10. franmosso

    franmosso In Fourth Gear

    Messages:
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    Location:
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    I looked at my 75 diagram , it is a white-red wire that goes from the sender directly to the bulk head connector. It then goes directly to the instrument cluster connector. No fuses in the circuit. Hope this helps.
     
  11. FrenchFan

    FrenchFan In Overdrive SILVER MEMBER

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    I'm not 100% sure but i think between the sender and the bulkhead ther's a grey 4 points connector. I will verify.
    Thanks franmosso, all the comments help.
     
  12. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    That is the one side of the bulb, so the other side has to be connected to 12 volts. FrenchFan, you did say you checked for power at the bulb with the key on, correct? If not, you should do that now. We know the power is getting to the cluster, as the ALT light does illuminate, but that does not automatically mean there is power at the OIL light's position. There could be a break in the foil. But if there is, then the socket needs to be examined, perhaps trading one socket for another as a quick test. Once it's established that the socket has power, then chase down the sender (grounding) side.
     
  13. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    Matter of fact, that sender lead, when disconnected from the sender, and tested with a voltmeter to ground, should show lower voltage, as the bulb drops voltage across it, when the key is in the ON position, should it not? Ohm's law should help you figure out the voltage drop at the bulb, which should also be what the voltage is at the sender connector.
     
  14. FrenchFan

    FrenchFan In Overdrive SILVER MEMBER

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    Location:
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    yes, h_a_cv64, i checked for power at the positive of the bulb, checked between the positive and the ground NOK.
    The printed circuit is new and i checked it from the position 14 to the positive of the bulb with an Ohm meter and i have continuity.
    I checked the grounder side by unpluging the wire from the sender and hooking it directly to the ground on the engine NOK.
    Will noot be at home during the week end of easter but will continue my investigations right after.
    Thanks a lot h_a_cv64, have a good easter week end.
     
    Last edited: Apr 19, 2019 at 3:18 PM

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