1. Welcome to Tacoma World!

    You are currently viewing as a guest! To get full-access, you need to register for a FREE account.

    As a registered member, you’ll be able to:
    • Participate in all Tacoma discussion topics
    • Communicate privately with other Tacoma owners from around the world
    • Post your own photos in our Members Gallery
    • Access all special features of the site

Alternator Draining Battery

Discussion in '1st Gen. Tacomas (1995-2004)' started by Green95Tacoma, Mar 19, 2018.

  1. Mar 19, 2018 at 4:08 PM
    #1
    Green95Tacoma

    Green95Tacoma [OP] Member

    Joined:
    Mar 19, 2018
    Member:
    #247772
    Messages:
    5
    Gender:
    Male
    First Name:
    Dalton
    Vehicle:
    1995 V6 4X4 Tacoma
    Afternoon all, I have been a long time reader but this is my first post. I have a 95 Tacoma V6 that has an electrical issue I can't seem to track down. When the truck is off I have a parasitic draw of about .4A. This goes away if I remove the Alt-S Fuse, Alternator Fuse, or disconnect the wires running to the alternator. I assumed it was a bad alternator so just bought a new one and installed it, however, I still have the same issue with the new alternator.

    Any ideas of things I should check that could cause a parasitic draw to the alternator that is not within the alternator itself?

    Thanks in advance.
     
    TXpro4X4 likes this.
  2. Mar 19, 2018 at 6:24 PM
    #2
    Sperrunner

    Sperrunner Respect the International Dibs Law

    Joined:
    Feb 23, 2018
    Member:
    #245334
    Messages:
    42,379
    Gender:
    Male
    First Name:
    Miguel
    Berkeley, Ca
    Vehicle:
    2016 ford transit
    Wd40, zipties, duck tape, and my hopes and dreams
    Just trace the wires there might be the smallest of cuts in the wire the is allowing voltage to be drawn. Possibly look for any arc marks as well.
     
  3. Mar 19, 2018 at 6:33 PM
    #3
    Green95Tacoma

    Green95Tacoma [OP] Member

    Joined:
    Mar 19, 2018
    Member:
    #247772
    Messages:
    5
    Gender:
    Male
    First Name:
    Dalton
    Vehicle:
    1995 V6 4X4 Tacoma
    Thanks, I will take a look and see if anything stands out. I am thinking it has to be a short or something in the wiring harness as well, or possibly the fuse box. I just had the old alternator tested this evening and it shows i is fine so I out it back in for now.
     
  4. Mar 19, 2018 at 7:33 PM
    #4
    Indy

    Indy Master of all I survey.

    Joined:
    Sep 15, 2013
    Member:
    #112518
    Messages:
    2,588
    Gender:
    Male
    Alternators don't pull juice. It's a 1 way street.
     
  5. Mar 19, 2018 at 8:01 PM
    #5
    Sperrunner

    Sperrunner Respect the International Dibs Law

    Joined:
    Feb 23, 2018
    Member:
    #245334
    Messages:
    42,379
    Gender:
    Male
    First Name:
    Miguel
    Berkeley, Ca
    Vehicle:
    2016 ford transit
    Wd40, zipties, duck tape, and my hopes and dreams
    Correct but if any of the wires insulation on the alternator circuit have be compromised there can be a very small draw from the battery
     
  6. Mar 20, 2018 at 12:51 AM
    #6
    Wyoming09

    Wyoming09 Well-Known Member

    Joined:
    Apr 24, 2015
    Member:
    #153833
    Messages:
    14,314
    Gender:
    Male
    New Tripoli Pa
    Vehicle:
    2000 Work truck 5 speed 4x4 3.4
    Super Springs
    A shorted diode will cause a drain

    Corroded plug can also cause a drain

    Most other major shorts will cause circuit protection to open
     
    cruisedon66 and Tim7902 like this.
  7. Mar 20, 2018 at 7:04 AM
    #7
    Green95Tacoma

    Green95Tacoma [OP] Member

    Joined:
    Mar 19, 2018
    Member:
    #247772
    Messages:
    5
    Gender:
    Male
    First Name:
    Dalton
    Vehicle:
    1995 V6 4X4 Tacoma
    I fist assumed a diode as well but after putting in a new (not rebuilt) alternator I have the same issue. The only curios thing was the drain was less (0.24A) with the old alternator than with the new (0.4A) which makes me think as Sperrunner mentioned I have an issue with wiring somewhere and the shiny new alternator made a better conductor. I hate to tear the wiring harness apart to trace the wires from the plug but that may be the next step...
     
  8. Mar 20, 2018 at 8:22 AM
    #8
    kgw

    kgw Well-Known Member

    Joined:
    Jul 9, 2012
    Member:
    #82260
    Messages:
    297
    Gender:
    Male
    First Name:
    kgw
    SoCal
    Vehicle:
    99 PreRunner
    140 amp alternator, Big 3 upgrade, Ultimate Headlight Mod, Trans Cooler
  9. Mar 20, 2018 at 1:37 PM
    #9
    Wyoming09

    Wyoming09 Well-Known Member

    Joined:
    Apr 24, 2015
    Member:
    #153833
    Messages:
    14,314
    Gender:
    Male
    New Tripoli Pa
    Vehicle:
    2000 Work truck 5 speed 4x4 3.4
    Super Springs
    I would never take the harness all apart unless you can see that it is burnt or rubbed maybe pinched some place.

    Any Physical damage should be easy to see.

    Any other loads on the alternator circuit I am not sure without looking
     
  10. Mar 20, 2018 at 1:42 PM
    #10
    BamaToy1997

    BamaToy1997 Wheel Bearing Master

    Joined:
    Jan 31, 2012
    Member:
    #71846
    Messages:
    10,800
    Gender:
    Male
    First Name:
    Bill
    Navarre, FL
    Vehicle:
    1997 Tacoma 4X4 AKA "Blue Beast"
    best wheel bearings around! www.marionbumper2bumper.com
    There is a main battery cable, and then the control harness for the alternator. If there is an internal short in the alternator itself (i.e. bad diode, internal wiring issue) then you will see a parasitic draw with the harness disconnected, but the main battery cable still connected. If the draw is caused by a control wire issue, or an ECU issue, then the draw will occur when the control harness is connected.

    Where are you measuring the draw at?
     
  11. Mar 23, 2018 at 10:36 AM
    #11
    Green95Tacoma

    Green95Tacoma [OP] Member

    Joined:
    Mar 19, 2018
    Member:
    #247772
    Messages:
    5
    Gender:
    Male
    First Name:
    Dalton
    Vehicle:
    1995 V6 4X4 Tacoma
    I set the multi-meter up in series with the negative battery terminal. The draw disappears when I disconnect either the control harness or main battery cable. Also disappears when the Alt-S fuse is removed.
     
  12. Mar 23, 2018 at 10:37 PM
    #12
    kbeefy

    kbeefy Active Member

    Joined:
    Jul 2, 2017
    Member:
    #222938
    Messages:
    29
    Gender:
    Male
    First Name:
    Ken
    Bend, Oregon
    Vehicle:
    2002 DCSB 3.4 AT 4x4
    Warn 9.5XP, E-Locker, Bil 5100
    Incorrect. An internal fault in the Alternator can cause a draw.
     
  13. Mar 23, 2018 at 10:39 PM
    #13
    TXpro4X4

    TXpro4X4 Fuck Cancer!

    Joined:
    Oct 29, 2011
    Member:
    #66093
    Messages:
    26,522
    Gender:
    Male
    First Name:
    Bryan
    Costa Mesa, CA
    Vehicle:
    2011 TOY
    Toy Stuff..... Front emblem led lighting. Under front bumper led rock lighting. Center counsel c.b mod with under the hood p.a Anytime foglight mod R.G.B tape light for inside toekick lighting. Front and back. CJumpers 700 lumens LED reverse lights. Front weathertech floor mats. De-Baged except TOY on tailgate. FJ style 6 speed shifter knob. Rubber tacoma bed mat. Trd exhaust. Trd 16in beadlocker style wheels Electrical a/c 115volt plug/usb mod next to passenger knee Fox 2.5 coilovers Icon 2.0's in the rear Rear locker any-time mod Abs kill switch mod
    Bad ground?
     
  14. Mar 24, 2018 at 7:40 AM
    #14
    Glamisman

    Glamisman Well-Known Member

    Joined:
    Oct 22, 2016
    Member:
    #200436
    Messages:
    3,242
    Gender:
    Male
    sometimes new parts are bad right out of the box.

    If I understand what is going on... your battery is not holding a charge. All electrical diagnostics start with verifying that the battery is good. If I remember correctly the large wire from the alternator goes into the fuse box "Alt S" and it is on a common buss that powers up the fuse box and also goes to to the battery. I am thinking to isolate the fuse box from the charging circuit and see if it goes away. Kind of tough to figure out not being right there and with no wiring diagrahm.
     
  15. Mar 24, 2018 at 7:55 PM
    #15
    wamego

    wamego Well-Known Member

    Joined:
    Sep 20, 2015
    Member:
    #164737
    Messages:
    190
    Gender:
    Male
    Vehicle:
    2002 Tacoma 2x4 TRD SR5
    You might start pulling fuses. Shut the door and pull any fuse that is hot when the key is off and see if the draw goes away. :burp:
     
    Sperrunner likes this.
  16. Apr 4, 2018 at 5:50 PM
    #16
    Green95Tacoma

    Green95Tacoma [OP] Member

    Joined:
    Mar 19, 2018
    Member:
    #247772
    Messages:
    5
    Gender:
    Male
    First Name:
    Dalton
    Vehicle:
    1995 V6 4X4 Tacoma
    Sorry for the delayed reply, I have been out of town for work. The battery is brand new and tests fine so I have no reason to believe it would be the issue. Was also experiencing the issue with the previous battery when I first bought the truck. Isolating the fuse box was my next thought as well but I haven't worked out exactly how to do that yet. I could simply wire the alternator directly to the positive terminal and remove the 80 Amp alternator fuse, but I am not sure how that would impact the Alt-S fuse. I have included a pic of the wiring diagram courtesy of Autozone's website :) (https://www.autozone.com/repairinfo/repairguide/repairGuideContent.jsp?pageId=0900c152800610de)

    upload_2018-4-4_18-50-1.jpg
     
  17. Feb 1, 2020 at 1:53 PM
    #17
    Kukablack

    Kukablack New Member

    Joined:
    Apr 29, 2018
    Member:
    #252014
    Messages:
    3
    Gender:
    Male
    First Name:
    Kuku
    Vehicle:
    2016 tacoma
    Hi there,

    I have the exact same problem you are describing with my 2014 4runner. Did you ever find out the cause?

    I see no update to this issue. Please would appreciate it if you fixed it and let me know the solution
     
  18. Feb 1, 2020 at 9:02 PM
    #18
    Glamisman

    Glamisman Well-Known Member

    Joined:
    Oct 22, 2016
    Member:
    #200436
    Messages:
    3,242
    Gender:
    Male
    from the toyota manual... slightly different.

    I hope you can read these. As I trace out what fuses go where I will upload the appropriate diagram. The 80 amp ALT fuse feeds the ALT-s fuse which feeds the heater and tail light relays.

    Is this draw at the battery post to cable or the large wire on the alt to the alt post?

    IMG-1265.jpg
    IMG-1266.jpg
     
  19. Feb 1, 2020 at 11:59 PM
    #19
    Kukablack

    Kukablack New Member

    Joined:
    Apr 29, 2018
    Member:
    #252014
    Messages:
    3
    Gender:
    Male
    First Name:
    Kuku
    Vehicle:
    2016 tacoma
    Thank you for posting the detailed reply. The draw is somewhere between ALT-S fuse and black connector (with L IG S M signal that go to IC Regulator) which attaches to the alternator. When I remove either ALT-S Fuse or the black connector the draw goes away. Alternator diodes tested good. Alternator tested good using Toyota specified test in repair manual..

    I am just perplexed what it can be. I can still drive the car without any issues with charging the battery but once I do not drive it for 3 to 4 days the battery is completely drained.

    Also, I noticed whenever I plug the ALT-S fuse back in place I hear 2 or 3 relays click in the fuse box.

    A little history...this issue started for me about a month ago. I was driving in heavy rain all day and came back and parked in my garage the lights started flickering and then stopped. On the same day while doing a stop on my way back I forgot that I kept my car running and accidentally tried to start it again as due to rain I could not hear the engine running.

    Also another month before that I had a new windshield installed as original one cracked due to stone hitting the glass.

    So now I am not sure what it is
    1. Starter shot something
    2. Alternator wiring connector (not the B post)
    3. Windshield related (but I was driving it for 2 weeks without any issues but first time in rain when this started)

    I think I am after a wild goose chase trying to figure out my electrical gremlins...

    Thanks

    KK
     
  20. Feb 2, 2020 at 3:21 AM
    #20
    Wyoming09

    Wyoming09 Well-Known Member

    Joined:
    Apr 24, 2015
    Member:
    #153833
    Messages:
    14,314
    Gender:
    Male
    New Tripoli Pa
    Vehicle:
    2000 Work truck 5 speed 4x4 3.4
    Super Springs
    I always had problems with batteries draining when the vehicles sat for a week or so.

    Strange as it seems when I upgraded to 1/0 welding cable on the main ground connections the problem went away in all the vehicles .

    It can`t hurt .

    Possible a relay coil was being energized something searching for a ground
     

Products Discussed in

To Top