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Alternaror noise test article

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I am searching for Moparman's Alternator "noise" test article. Cant find where it is. I want to check and see if my alternator is 100% or not

 

Does Alt noise have to do with a bad diode? I saw a Alternator part on Larry Bs sight. (Diode pack / Rectifier Bridge for Deanso Alternator)

Is that "the fix" if your Alternator is making "noise"

 

I think I checked my alt a few years ago, before I replaced my TPS

 

Rick

Edited by GSP7

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    • GSP7
      GSP7

      Does the big fuse need to be removed to get a proper AC reading?   Is this test procedure explained in my big 2 book service manual ?

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    • Author

    That was a thread

     

    I thought there was a article/ write up on how to test a Denso Alternator for "noise" or a bad diode

     

    I clicked the "Article" button at top of this page but didnt find a alternator test article

     

     

    .

    • Author

    Why did you take the big fuse out?

     

    I have a small volt meter that has the plug in needles.  Are you just going from Testing DC and then testing at AC

     

    What will it read at AC if you have a damaged diode?  Will it read 14 volts also just like hooked up DC

    Edited by GSP7

    The Big fuse connects the battery to the alternator.  By removing it you keep any AC signal made from the alt from getting to the battery or any other computers in the truck and causing the issues.

     

    Yes, an AC signal coming from the alt is caused by a leaky/defective Diode.  

    • Owner
    Why did you take the big fuse out?

     

    System isolation. If the field wiring and the charge lead is disconnected there should be near zero or zero AC noise.

     

    What will it read at AC if you have a damaged diode?

     

    Normal alternator is 0.01 to 0.02 Volts AC

     

    Marginal alternator is 0.05 to 0.09 AC Volts

     

    FAILED alternator is any voltage above 0.1 AC Volts.

    •
    • Like 1
    • Author

    Where did you buy your test meter?  My two small meters arent for automotive

     

    My goal is to make sure my alternator is ok. To protect my ECM.

     

    I read that bad alternator diode causing alternator noise can harm the ECM, If that is true

    Edited by GSP7

    Where did you buy your test meter?  My two small meters arent for automotive

     

    My goal is to make sure my alternator is ok. To protect my ECM.

     

    I read that bad alternator diode causing alternator noise can harm the ECM, If that is true

    Not only the ECM, but it can also harm the PSG on the top of the injection pump! 

    • Owner

    Where did you buy your test meter?  My two small meters arent for automotive

     

    My goal is to make sure my alternator is ok. To protect my ECM.

     

    I read that bad alternator diode causing alternator noise can harm the ECM, If that is true

     

     

    Not only the ECM, but it can also harm the PSG on the top of the injection pump! 

     

    Actually anything electronic right down to your cell phone plugged into the power point charging, GPS hanging off the windshield, to maybe you stereo in your dash. So anything electronic hooked up to the electrical system of the truck can and will be affected by the AC noise produced by bad diodes.

    •
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    • Author

    Where did you buy your test meter and what brand/kind  is it?

    • Author

    Is this test procedure explained in my big 2 book service manual ?

    Edited by GSP7

    • Author

    When using the multimeter to check DC and then AC, should the big fuse be removed to get a proper AC reading?

     

    I still get 14 volts on AC.  I dont have a  dial on my meter. You have to put the pin in the AC hole on the meter.  Im using a cheap old needle type volt meter. (not digital) and its not detailed enough to even read .1 or .01 or .001.  This meter is probably 40 years old.

    • Owner

    Time to update to a new DVM (Digital Volt Meter). Alternator AC power is variable AC frequency that changes with RPM. So you can't buy a cheap hardware store meter for household 60 Hz. It has to be able to measure variable frequency.

     

    https://www.youtube.com/watch?v=MGaHaIXZioA

    • Author

    Does the big fuse need to be removed to get a proper AC reading?

     

    Is this test procedure explained in my big 2 book service manual ?

    Edited by GSP7

    • Like 1

    Does the big fuse need to be removed to get a proper AC reading?

     

    Is this test procedure explained in my big 2 book service manual ?

    No

    No

     

    This isn't an issue dodge foresaw, so it won't be in the manual. You only remove the fuse to see if that is the reason for torque converter lock/unlock issues. 

    It's really easy to do. Get a high quality meter, set it to V~ or Vac (Whichever your meter has.) Then start the truck and put a lead on each of the driver side battery posts. 

    • Author

    No

    No

     

    This isn't an issue dodge foresaw, so it won't be in the manual. You only remove the fuse to see if that is the reason for torque converter lock/unlock issues. 

    It's really easy to do. Get a high quality meter, set it to V~ or Vac (Whichever your meter has.) Then start the truck and put a lead on each of the driver side battery posts. 

    Thank you ,  Yeah , Im online looking for a Good multimeter. I found a old new in box Fluke 85 like in the video on ebay 6d bid wait.

     

    Is that fluke 85 kinda outdated not able to do modern auto computer tests, like that last diode test video? That snap-on tester is probably $1000+ scope/meter Id guess

     

      Also looked on line at some of napa's, o'riely's, autozone's but they might just have cheap junk in their stores

     

    Can you guys refer me to a good Digital Volt Meter for testing my truck that wont break the bank?    I saw some for $300-500+++

     

    Rick

    Edited by GSP7

    Even a cheap HF one will do the job, I got one used in a lot of stuff and it reads dead on with my flukes.  So I keep it in the glove compartment.

     

    Extech was supposed to be a good brand as well, but I'm not impressed and likely won't buy any more meters from them.

     

    I've had an INNOVA 3320 one for at least 5 years, besides the buzzer not working, it still works fine.  It's been dropped, rained in, disassembled...  

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