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Pulsing lights

Discussion in '4 Cylinder' started by jambet, Sep 3, 2010.

  1. Sep 3, 2010 at 5:15 PM
    #1
    jambet

    jambet [OP] New Member

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    I need some help here. My mech doesn't have much of an idea of what's going on. I have an 03 2.4 with 160K. When I start up in the am, my lights' odo, and ashtray light pulse. It is not necessary for me to turn on the lights as the dome light will exhibit the same problem. Battery, starter, and alt check out ok. Anybody else experience this? Thanks.
     
  2. Sep 3, 2010 at 5:26 PM
    #2
    tacomaman06

    tacomaman06 Carolina Alliance: Enforcer

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    getting there....
    sounds like you have a bad ground somewhere.
     
  3. Sep 3, 2010 at 5:38 PM
    #3
    larryde09

    larryde09 Well-Known Member

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    x2....maybe try pulling the less important fuses to try to isolate the culprit. Do they pulse when the engine is runing and/or off? Try turning the headlights and blinkers on and off, maybe you'll be able to trace where the problem may be coming from. This could be a tough one to track down.
     
  4. Sep 5, 2010 at 5:33 PM
    #4
    gooberpeas

    gooberpeas Active Member

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    as a general rule, pulsing lights indicate a defective voltage regulator, which is usually built into the alternators these days....

    might want to recheck that alternator......just a thought.
     
  5. Sep 6, 2010 at 5:29 AM
    #5
    larryde09

    larryde09 Well-Known Member

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    x2...good call, I was thinking of some sort of grounding issue. What if you disconnect the alternator? You should be able to start and run the truck on the battery alone for awhile. In theory, if the alternator is disconnected, the pulsing should stop.
     
  6. Sep 6, 2010 at 5:38 AM
    #6
    jhodge83

    jhodge83 Any dog under 50# is a cat and cats are useless... Moderator

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    wat?
    correct. i had this issue after replacing my mud gunked alternator and getting one from advanced that had a bad voltage regulator. luckily i have a head unit that will show the voltage and i could see it pulsing. if the battery is disconnected, everything should be fine.

    when the auto places check the battery/alt, they always have you turn your truck on mid-test. for me, it wouldnt start acting up until a few minutes after turning on. i made them wait until i could hear it cycling from under the hood and it finally registered as a faulty regulator.
     
  7. Sep 8, 2010 at 8:57 AM
    #7
    jambet

    jambet [OP] New Member

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    Thanks fellas. Been so busy at work that My first chance to check out the Alt. was this am. Doing the easiest thing first, I disconnected the alt and, bingo, the pulsing was eliminated. Reconnected the alt and the pulsing returned. Now to find a good alt. Thanks again.
     
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