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Electrical

Discussion in 'The Garage' started by 79Stomper, Mar 15, 2005.

  1. 79Stomper

    79Stomper 1/2 ton status Premium Member GMOTM Winner

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    What provides a continous 12 signal even while starting? I am sitting here scratching my head and trying to figure this one out. I know all accessories die when you turn the key to start but what stays constant while cranking? I am thinking distributor, hot wire going to coil, but want to have a warm and fuzzy before I go and splice into that wire.



    TIA
    James
     
  2. wraenking

    wraenking 1/2 ton status

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    can you just spade into the ext5ra spots on the fuse panel? i think there are 2 spares
     
  3. dyeager535

    dyeager535 1 ton status Premium Member

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    If your fuse panel uses blade fuses, use the accessory terminals on it.

    You thinking along the lines of memory for a digital radio, etc., or you just want 12V with ignition in any position other than off?

    Splicing into any existing wire should be the last option you use, as its the worst way to get power.
     
  4. nvrenuf

    nvrenuf NONE shall pass! Premium Member

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    Continuous, meaning even when the truck is off? Wouldn't the dist only be ignition hot? I would think the only truly continuous & uninterupted source would be the battery.
     
  5. 79Stomper

    79Stomper 1/2 ton status Premium Member GMOTM Winner

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    This is for my FI computer to run off of. I need it to be switched (with the key)with the ignition while turning the truck over and still provide power while truck is running but not when it is off.


    Thanks for the quick responses.
     
  6. dyeager535

    dyeager535 1 ton status Premium Member

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    So this isn't the continuous 12V to keep the ECM's "memory" then.

    Again, fuse panel matters. All the blade panels I've seen have spare terminals, which should have spare ignition hot terminals. Put a voltmeter in the spare terminals, check for voltage with key off, then turn key to run and check again. On my fuse panel I didn't find any terminals that were hot with key in the "run" but not in the "crank" position. Mine's also an '86, which is a different blade fuse panel than '84-older(?) but similar with the spare terminals.

    Still going to need an inline fuse with the correct rating for that ECM circuit, but that will be the best way.

    If glass fuses, no idea if those panels have spare terminals that can be used like the blade ones.
     
  7. BigBen

    BigBen 1/2 ton status Premium Member

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    The distributor and solenoid stay "hot" during cranking for sure. Otherwise the truck wouldn't start.

    The Solenoid is dead once you return to "run".

    The distributor is definitly hot for "run" and "start". (Assuming HEI. Voltage changes with points)

    I'd have to look at the swich schematic to tell you what else is hooked up during actual cranking... and I don't have that here at work.
     
    Last edited: Mar 15, 2005
  8. 79Stomper

    79Stomper 1/2 ton status Premium Member GMOTM Winner

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    That is what I am thinking too. I will just splice into that wire to run my computer power off of.

    Thanks.
     
  9. clarkjw24

    clarkjw24 1/2 ton status GMOTM Winner

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    Hey James I found mine by switching the truck on and with a test light finding a hot. Then tested each of those while someone turned over the ignition. If I was home I'd tell you the color but I'm at work.
     
  10. 79Stomper

    79Stomper 1/2 ton status Premium Member GMOTM Winner

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    Thanks, but the color of the wire wouldn't reallyhelp. remember when I said the truck had been stolen? Well that is one of the wires that they jacked all up and I replaced it a few years ago. As well AS QUITE A FEW OTHERS UNDERNEATH THE DASH. I am just going to run it off of power wire going to the distriutor and call it a day.
     

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