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Alternator not Charging

Discussion in 'Electrical' started by Bill2010Tundra, Jan 9, 2022.

  1. Jan 9, 2022 at 7:04 PM
    #1
    Bill2010Tundra

    Bill2010Tundra [OP] New Member

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    ISSUE: Alternator not Charging

    I have an issue with my 2010 Toyota Tundra 5.7L that cropped up about 6 years ago, fixed itself and now showed up again. I will state all the facts I can recall and have figured out so far to draw the best picture I can.

    Back at that time when it was fixed 6 years ago, the technician had said the problem went away when he wiggled some wires in the steering column. So no real clue to the real issue.

    Symptoms:
    Battery not charging. Alternator not putting out any higher voltage or is being held down somehow to not allow charging. I can start the engine, but the battery shows on the gauge as about 12v and only goes down slowly with engine running. I can drive but the battery does not get charged. I have to recharge at home.

    Still have a number of dash warning lights on.

    Windows stuck in position and don't operate. No fan, AC, heat, seat heat, seat does not reposition, no turn signals. Door locks work. Head lights and brake lights are working. I am trying to minimize usage to keep battery up longer.

    Engine starts just fine, runs good, revs up good, great running engine. Will not put charge voltage when revved up.

    What could hold back charging of battery from there? What else would hold battery at less than 12.6 volts or what would turn off charging if battery it gets lower or is still lower than 12 volts? Is there something else than internal to the alternator that tells alternator to not generate higher voltage to cause charging?

    I believed it to be the Battery and Alternator so I had Toyota service check change them out, they tested and agreed they were bad. Now I have new parts there. Still having the same issue. The Technician and another Master Tech took some looks and could not figure the issue. They did not want to spend any further time and my $$ to chase the issue and I agreed with them (at that price). They did not think that the Toyota maintenance phone support engineer service would be able to diagnose or support anything on the issue either.

    Thanks for any ideas and questions to get closer to the answer.
    Bill
     
  2. Jan 16, 2022 at 10:47 AM
    #2
    Bill2010Tundra

    Bill2010Tundra [OP] New Member

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    I have been testing the Cables, connectors and fuses on this 2010 Tundra and not found anything wrong with them. Question coming up now is about the voltage regulator. Is the voltage regulator internal to the alternator or is it a separate external device? I am finding that the battery does not go down very much while driving the truck, but it really does not get charger either when driving. The voltage output from the Alternator stays about the same as the battery voltage when idle and revving the engine. That is the point where I am now in checking this out, as the same issue continues. Anybody know?
     
  3. Jan 16, 2022 at 12:35 PM
    #3
    ColoradoTJ

    ColoradoTJ Certified tow LEO Staff Member

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    I assume you have checked all fuses?

    I would check/change out all associated fuses/relays. They can go bad over time.
     
    azs406 likes this.
  4. Jan 16, 2022 at 4:17 PM
    #4
    Bill2010Tundra

    Bill2010Tundra [OP] New Member

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    All fuses and relays were removed and confirmed operational. There are lots of them! Visually, the fuses all look in good shape. All, fuses and relays, were also measured for being shorted and definitely 0 ohms.
     
    ColoradoTJ likes this.
  5. Jan 16, 2022 at 9:23 PM
    #5
    azs406

    azs406 New Member

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    Did you check for power before and after fuses?
     
  6. Jan 16, 2022 at 10:18 PM
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    ColoradoTJ

    ColoradoTJ Certified tow LEO Staff Member

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    Well we have a process of elimination:

    New Alternator…checked good.
    New battery…checked good
    Fuse/relay…checked good.

    Next I would be looking at and shooting wires. The troubling part is this happened 6 years ago and magically fixed itself.

    At this point, all other things being correct, it has to be a wiring issues someplace.
     
  7. Jan 17, 2022 at 3:33 AM
    #7
    MT Madman

    MT Madman Just an ordinary guy

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    I go with making sure all your connections are clean and corrosion free.
     
    Tripleconpanna likes this.
  8. Jan 17, 2022 at 5:07 AM
    #8
    TundraMcGov.

    TundraMcGov. Your friend. Your foe. Not yo Ho.

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    Like grounding points? Yes. Like grounding points.
     
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  9. Jan 17, 2022 at 9:55 AM
    #9
    Bill2010Tundra

    Bill2010Tundra [OP] New Member

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    I am working to quantify some of these ideas still. But some more data points and questions at this point:

    The battery light is not on, I am keeping the battery above 12v after I drive it any. I have not driven it much. I have only taken a few short drives for checking and to wash off the engine grease for working on. I recharge when I get back home to keep the battery up.

    - There are some dash lights on constantly: ABS, Check engine, skid, TPM, Airbags
    - Must use shifter bypass to get out of park.
    - Odometer is stuck at fixed value - not changed in 12 mile drive.

    The battery terminals and ground terminals near battery are cleaned. I cleaned them up after installation of new battery, they had some slight corrosion, but mostly greasy and dusty prior. I have checked some chassis grounds at different places and all are good. I have not checked deeply - like at the alternator - hard to get to, that's next.

    Where is the Alternator ground point? I believe it is grounded thru the alternator chassis directly to the engine mount, but looks like it might a heavy wire going over to the battery and then the truck body chassis along with the positive side of the alternator. That makes sense to have both the + and - side alternator to battery connection, but I don't see another wire connection at the Alternator.

    That alternator is a tough space to get to, I saw a picture (attached) that it has a copper threaded bolt for power connection, but not a separate one for ground, so I assume it is the chassis. There is also a 4 pin connector that looks like it goes to the ECU for power directly to it and couple other signals. Would this maybe be a control from the ECU to the voltage regulator maybe? Thinking here - maybe the ECU has gone bad. Ouch, that would not be a happy day. So is there a way to test the ECU - DIY wise at home?

    I checked the voltage at the fuses. When the power is off, it is the same thru the fuse as would be expected/hoped (on both sides). Some fuses have a voltage when engine is off and the voltage is the same thru. I have not turned on any extra accessories to see any change or voltage drop.

    Any other ideas and questions to check are super welcomed.

    Bill

    Alternator.jpg
     
    Last edited: Jan 17, 2022
  10. Apr 16, 2022 at 11:02 PM
    #10
    AstroDude

    AstroDude New Member

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    I'm interested to see if this was fixed. I'm have the same exact problem after replacing my rack and pinion...

    - New optima battery (1 week old)
    - New Toyota OEM 150V alternator (installed today)
    - Replaced the 180 amp use strip in the engine bay (the old one was good

    Today the battery died and I measured the volts at 11.48 before the battery died.
     
  11. Apr 17, 2022 at 9:19 PM
    #11
    Bill2010Tundra

    Bill2010Tundra [OP] New Member

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    Well it is not fixed yet. Found to be the Main ECU inside the cab, driver side under fusebox, at your left knee. The ECU is bad and currently awaiting for Toyota replacement unit. Part has been on back order for 2+ months now. The current supply chain problem - I am awaiting for that part to come in and they keep delaying it a month at a time. There is something wrong internal to the Main ECU unit. Even after this is fixed, there may be more problems to chase down. That will be unknown until this part is replaced and we can test the rest of the way thru.

    So it is not fixed, but it is at least now known.
     
    AstroDude likes this.
  12. Apr 18, 2022 at 5:39 AM
    #12
    Jeff_5_7

    Jeff_5_7 New Member

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    Bill we fixed @AstroDude s truck yesterday by isolating the 7.5A LH-IG fuse in the body control module (Ecu under driver side dash with interior fuses). He had very similar problems and replacing the fuse fixed his. He mainly mentioned alternator not charging and blinkers not working as you do. His 7.5A LH-IG fuse wasn't completely blown but it wasn't making good clean contact. Replacing it fixed his issue. You can read more about it here https://www.tundras.com/threads/low-voltage-ive-replaced-everything.106100/

    I should also add the LH-IG fuse is tied to the ignition of the truck. When the ignition comes on it provides power to the IC regulator in the alternator to enable it to charge, it also provides power to the flasher relay, seat heater, mirror heater, and some other circuits.

    As far as AC, Fan, Heat, Seat Memory, Shift lock control, ABS Module (Odometer) I would look at fuse 7.5A ECU-IG No.1. It does similar function providing power on ignition for the AC, Shift Lock, ABS Ecu and Seats. The odometer not working and all the ABS lights on means the ABS ecu is not getting power. I bet your speedometer is not working either. It gets its signal from the ABS ecu. Does you AC panel even light up at all? The little green leds? The AC control panel is powered by this fuse as well.

    IF the truck is still in your possession, not sitting at your dealer could be worth pulling and replacing some fuses in the body control module under the dash to see if it helps. These two fuses are right next to each other in the control module. Astrodudes old fuse did not look in good shape however it was still testing as good. He had to remove it and then we noticed visually it didn't look great so it was replaced.

    I would definitely be taking a good look at the area of the fuse box. Looking to make sure terminals are good and clean and new clean fuses are installed. Hopefully this also helps you.

    I would add its not very common that an entire ECU goes bad. Its not impossible however its just at the end of the list of things that are most likely to be wrong.
     
    Last edited: Apr 18, 2022
  13. May 15, 2022 at 1:44 PM
    #13
    Bill2010Tundra

    Bill2010Tundra [OP] New Member

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    My sincere apologies on this. I lost this email and now back to it. My truck has been in the shop awaiting parts from china or wherever they come from. I need to go get it and pull out of the shop and check this out. The answers I have so far is from a very young tech at a Toyota shop that got rid of their Master Technicians a few years back. They are not clueless but they were pretty much out of ideas on what it may be. I have not been very comfortable, and of course they caveat this all with "this will let us go to the next step looking for the issue". Already at $1,500 and waiting for parts after couple months. We actually went there last weekend looking for a new vehicle - VERY bad experience on the sales side made me think again about the 7th time working with this place!

    This will take a bit as I am going out of town for a few days. I will post the results when I get it tested out.
     
    TundraTRD08 and Jeff_5_7 like this.
  14. Jul 4, 2023 at 8:02 PM
    #14
    TundraTRD08

    TundraTRD08 Somehow I fit 37s on a level

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    Any update? I have had this happen 3 times now. The first two times a new fuse fixed it, but now it’s not. I am getting power to the fuse though, tested by a multimeter. It was the same as the battery. It has ran down to 12.3, but the alternator isn’t charging so I’d expect that. Bought the battery yesterday, and I have a new alternator
     

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