How to check ignition wire voltage

Discussion in 'Sparky's corner' started by chrisk, Aug 7, 2015.

  1. chrisk

    chrisk Well-Known Member

    Does anyone know how to check the ignition wire voltage on both sides of the bulkhead connector in my 1967 Buick Skylark? The resistor wire is burning hot and it's not letting the alternator charge the battery like it should. I have a new alternator, but it won't charge the battery, it only gets 12.5 volts when its running but it should like 13.9 or 14.2. I believe that the problem is the ignition wire and after I do check it (once I figure out where to check), how many volts should it be? Thanks.
  2. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    The resistor wire has nothing to do with your alternator. All it does is drop the running voltage to the coil so that the points last longer. If you have a charging problem, it may be a bad alternator (new means nothing today, unfortunately), bad regulator, or wiring between the two. It is not unusual for previous owners to hack up the wiring on an older car. Not quite sure what you are referring to when you mention the ignition wire. Those run between the distributor and spark plugs.
  3. buick64203

    buick64203 Just plum crazy Staff Member

    The resistance wire feeds voltage to the points. Not sure how it would cause a charging problem. Are you still running points? Does it get hot while the car is running or when the ignition is on and the engine is off?
  4. 436'd Skylark

    436'd Skylark Sweet Fancy Moses!!!!!

    If the resistance wire was shorted it would put a massive load on the alternator. It shouldn't get burning hot, that in itself indicates there is a problem somewhere. if it was shorted badly enough one of the fusible links would pop. If it hasn't already and been eliminated. I would trace the wire and inspect thoroughly for a rub through and them ohm out the coil. you might try rigging a test wire to the coil with some sort of resistor to inline and see what happens.

    also, are you getting 12.5 at an idle? if its the original stock type externally regulated alternator that's about all it will put at idle. Where is it at 2k?

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