Help with checking alternator

Discussion in '94-95 5.0 - Specific' started by 883cobra, Dec 12, 2013.

  1. 883cobra

    883cobra New Member

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    I need to check the alternator with my meter but I have no experience in doing this.Any guidance is greatly needed.I am doing some self-educating online with how to do this but some advice for fellow mustang owners would be just as helpful.
    Oh...incase you are wondering why?the voltage gauge on my cluster moves back and forth regularly.The voltage gauge goes between the "R" and the "A".I have checked the belt as well the tension on the belt.I have noticed that one of the PO's did some work on the wires at the alternator(see pic) so I am thinking that wires are not making a good connection where the splice is.Before I go tearing into the old repair I would like to check the alternator with my meter.
    [​IMG]
     
  2. CC'S95GT

    CC'S95GT Legend

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    I don't thing the alt wire looks any different than mine, Maybe I'm missing somethine though.

    To ck the alt.- put ohm meter on DC volts and connect to battery. Red lead to pos., black lead to neg. Start car.
    Voltage should be about 14.2 +/- .5 running at any rpm. You can also vary the RPM's but the voltags should settle back to the origional volt. at idle.

    Was you a/c or defrost on when the guage is bouncing? The engagement of the a/c compressor can put an extra load on the engine and cause the needle to bounce too.
    If the a/c compressor is engaging and disengaging, that is a sign the freon is low.
     
  3. ttocs

    ttocs Legend

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    that really isn't a good test for the alt as it tests the voltage but not the current output. Take the car to vatozone or a shop and they have a tool they hook up and will have you ref the motor to see what current it puts out.


    so the instructions would be
    1 go to vatozone
    2 say I want my alt tested
     
  4. 883cobra

    883cobra New Member

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    I thought about the a/c or defrost causing it.I have at times checked to see if it made much difference turning them off an on while driving and it didnt.When I replaced the valve cover gaskets I had to lift the alternator out of the way,that's when i noticed the alternator wires had be worked on.That is when the gauge started to fluctuate.
     
  5. shoua50

    shoua50 New Member

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    Checking your alternator with a meter will only check the voltage regulator and not amperage. You can have good voltage but low amps so you really need an amp meter to check both. Purpose of an alternator is to recharge the battery after cranking or it gets low, it also supplies power to everything in the vehicle so the vehicle is actually running off the alternator. If your gauge is bouncing around at idle and you think it's due to a bad alternator, here's a redneck way of checking it - take your serpentine belt off and hook some good jumper cables to your battery cables and hook the other end to another vehicle with a good alternator, crank up your vehicle then crank up the other vehicle, if problem goes away then you alternator is bad cause now you vehicle is running off of the other vehicles alternator, if problem is still there u got a bad gauge. I would still look at the wiring though because the 12 volt feed at your alternator connector goes from the battery to the instrument cluster thru the cluster to the alternator. I have seen burned up clusters in both fox bodies and sn95 for no charging issues.
     
  6. DeepList

    DeepList Administrator Admin SN95 Supporter

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    I wouldn't advise doing that.