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gauge wire size - 6 volts to 12

Discussion in 'The Hokey Ass Message Board' started by AV8 Dave, Aug 4, 2010.

  1. AV8 Dave
    Joined: Jan 3, 2003
    Posts: 680

    AV8 Dave
    Member

    Hi Everyone! Rewired my buddy's shoebox and kept the stock gauge cluster. Installed a Ford constant voltage regulator and none of the gauges are working properly. Temp needle only goes down to the first bar with a stone cold engine. Fuel needle doesn't even move up with the tank about half full and a test light on the tank sender terminal pulses regularly on and off. The ammeter needle doesn't move either way with ignition and all the lights on. Not sure about the oil pressure as I have yet to flash up the engine. I'm wondering if it's because the new harness gauge sender wires are all 18 gauge. This is my first full rewire and everthing else seems to be working fine. Any help greatly appreciated! Regards, Dave
     
  2. wire gauge size should have nothing to do with it. you need some type of voltage reducer for 6 volt gauges and sending units to fuction properly in a 12 volt system.
     
  3. stude_trucks
    Joined: Sep 13, 2007
    Posts: 4,755

    stude_trucks
    Member

    When volts goes up, wires size can go down. Lower volts means higher amps for the same watts. In other words, a 10 watt bulb at 12 volts will be lower amps than a 10 watt bulb at 6 volts. Wire size is based on amps, not volts. Watts = volts X amps

    The problems you are describing are not related to volts or wire size. Things would still work regardless of wire size, but if the wires are too small for the amps, they just heat up and will melt if too stressed.

    When I converted my '53 truck for 6 volt to 12 volt, all I did was change the battery, generator, voltage regulator and light bulbs. Again, since the wires need to be bigger for 6 volt than 12 volt, they wires were actually less stressed and ok as is (except I cleaned all the connections too and replaced damaged wires).

    The only gauge that didn't work properly was the fuel gauge because that is the only one that changes with voltage as it measures resistance in the circuit as the float changes angle. Because the voltage change also changes the resistance in the circuit, it messed up the reading and I wasn't smart enough to figure out how to add the proper resistor to the circuit to correct it. It runs on propane now anyway, that that problem is no longer an issue.

    I am pretty sure I had to change from a positive ground to a negative ground too. But, I just changed that and flipped wires as I though necessary.

    I am no electrical genius by any means, but I was able to figure it out pretty easily as I went along, except for the gas gauge of course.

    Not exactly sure what your problems are being caused by, but maybe just run through each item at a time again and make sure things are wired up as they seem like they should be. It sounds stupid, but maybe you got a wire or 2 crossed. It's easy enough to do.

    Short of that, things fail at connections. Check all connections and make sure they are nice and clean and tight.
     
    Last edited: Aug 4, 2010
  4. AV8 Dave
    Joined: Jan 3, 2003
    Posts: 680

    AV8 Dave
    Member

    Thanks guys! Guess I just needed to know that the wire size was not an issue as I'm certanly not the sharpest tool in the shed when it comes to all things electrical! I will double check everything and try again. Many thanks for your responses! Regards, Dave.
     

  5. david38rc
    Joined: Mar 24, 2010
    Posts: 71

    david38rc
    Member

    You can never have too many grounds on automotive electrical circuts. Poor grounding leads to electronic misery.
     
  6. AV8 Dave
    Joined: Jan 3, 2003
    Posts: 680

    AV8 Dave
    Member

    Thanks ic237! I'll check it out! Regards, Dave.
     
  7. AV8 Dave
    Joined: Jan 3, 2003
    Posts: 680

    AV8 Dave
    Member

    Yes, that's one avenue I will definitely check out as I am having a problem with some of the gauge cluster lights! Thanks david38rc!
     
  8. d2_willys
    Joined: Sep 8, 2007
    Posts: 4,165

    d2_willys
    Member
    from Kansas

    Only issue is that the power is also reduced significantly. Why 12V gets more bang for the buck is the volts. You use less current (amps) to get equivalent wattage. This is why a 12 volt bulb has more resistance but generates same wattage (as a 6V bulb) with less current draw.

    48W/6V =8amps, 48W/12V = 4 amps


    As far as wire sizes go, the only wires I would verify (at the instrument panel) are 10 gauge are the wires to and from the ammeter. 18 Gauge will NOT be sufficient, and might just make your ammeter appear to not work.
     
  9. NOTE TO SELF:
    Go ahead and get that fire extinguisher now!
     
  10. nico32
    Joined: Oct 30, 2008
    Posts: 717

    nico32
    Member
    from fdl, wi

  11. AV8 Dave
    Joined: Jan 3, 2003
    Posts: 680

    AV8 Dave
    Member

    d2_willys: The car is at my buddy's place but I checked the wiring manual and it shows that wire as being an 18 and I seem to recall it being fairly easy to thread through the loops! I will check it out this evening - many thanks for the tip! RuFFDaWG: Yes, as it's my first full rewire, I've had an extinguisher close by at all times! Only smoke I had was from a new ballast resistor (for a short time) but I understand they're supposed to do that when new. nico32: Thanks for the referral to another reducer! Will check it out. And thanks again to all of you for your help! Regards, Dave.
     
  12. d2_willys
    Joined: Sep 8, 2007
    Posts: 4,165

    d2_willys
    Member
    from Kansas

    18 gauge wire seems a bit small, unless the ammeter is a shunt type. I would recheck this since everything except the starter itself goes through the ammeter. 10 or 12 gauge is more the size it should be.

    If you need a voltage reducer for up to 16 amps then PM me. I have a new product that you may be interested in. It is a solid state reducer, not one of those resistor blocks.
     
  13. AV8 Dave
    Joined: Jan 3, 2003
    Posts: 680

    AV8 Dave
    Member

    The ammeter is just the stock King Seeley type with the two metal rings on the back that you just run the wire through in a loop. The gauge senses the current flow and registers it accordingly. I will double-check the current path tonite as well as the individual gauge hookups. Thanks for the heads-up on your new product! Right now, I have a stock "constant voltage regulator" from a later Ford product. Thanks again for your help!
    Regards, Dave.
     

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