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2001 SR5 4hi light flashing and 4x4 not engaging

Discussion in '1st Gen Tundras (2000-2006)' started by RHP, Jan 18, 2023.

  1. Jan 18, 2023 at 10:08 AM
    #1
    RHP

    RHP [OP] New Member

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    Howdy ya'll! I'm a new member. Thought I'd make a post about this because I've gone through (what seems to be) every forum on this problem.

    Recently bought a 2001 SR5 of FB for pretty cheap. Found out the 4x4 doesn't work (rookie mistake) and tried a bunch of stuff to fix it.

    Before tampering with things the 4lo and 4hi would seem to engage (dash lights would turn on properly) but front wheels would not have power. When I would hit the buttons I could hear the transfer case actuator motor engage but not the ADD actuator. This was before I had done the extensive research that I have done now. I ignorantly opened the transfer case actuator and broke a bolt in the process. I had re threaded a new bolt where the old one was, but I believe that it did not fully seal and got water into it. Then the 4hi light would just continue to flash and when I would press the 2wd/4hi button nothing would happen. No noise from the transfer case actuator or the ADD actuator. I assumed that I had ruined the t case actuator and proceeded to replace it with a brand new part (found it for a third of the price on FB).
    After replacing the t case actuator I thought all would be fine and dandy, but the 4hi light is still flashing. However, now when I press the 4hi button to disengage the 4wd I can hear the ADD actuator moving, but nothing from the new t case actuator.

    I'm wondering if this could be an electrical problem with one of the switches. When I unplug the main switch (the one with like 6 or 7 prongs) the 4hi and 4low lights will flash. That means that there is some connection with that switch. However, when I remove the other 2 switches, the ones on the side of the actuator, nothing happens. No change in dash lights or anything. Im wondering if these could be faulted? How would I check?

    Also when I press the 4lo button, nothing happens. No lights, no noises.

    It's a bummer cause this is a super solid truck besides this and I'd prefer not bringing it into the shop. (College kid lol).

    If anyone has any ideas please let me know! Any recommendations is very appreciated!
     
  2. Jan 18, 2023 at 10:11 AM
    #2
    shifty`

    shifty` I might be an adult, I'm a minor at heart

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    "Hey, I'm a new member, I exhausted the usefulness of other forums, then left, and it's your turn now..." :rofl:

    That's an interesting way to start out, but I guess I appreciate it. 2/3 of the people who come through are just here to use for quick help and jet, at least you're up front!

    Stupid question, did you check the 4WD fuse in the dash fuse panel, first and foremost?

    A few different members have had the 4WD ECU short out and cause all kinds of stupid stuff. But given all the times you've been up in stuff, replacing things, my confidence is low in how to tell you to proceed. But if you did have a JY nearby with a truck that has a good working 4WD ECU, could be another way to test.

    Also, 4LO won't engage unless 4HI successfully engages and you've got it in neutral.
     
    NickB_01TRD likes this.
  3. Jan 18, 2023 at 10:23 AM
    #3
    RHP

    RHP [OP] New Member

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    Hahaha I'm not really planning on being one of those people that just asks for help and never is seen again in this forum. Mostly just been reading a ton, haven't made a post till now. I love these trucks and want to make a nice build of it. I did check the 4wd fuse and it looks fine and when its removed the 4hi light wont come on. I had seen a couple of threads about the 4wd ECU's but thought they were for later model tundras (2nd gen and beyond). I will read more into that.
    Thanks!
    I'll keep updates on here.
     
  4. Jan 18, 2023 at 11:19 AM
    #4
    shifty`

    shifty` I might be an adult, I'm a minor at heart

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    You may be right on the 4wd ECU. I'm not super well versed on the 4WD stuff. But there's links to a copy of the 2000-2003 FSM here that can probably walk you through troubleshooting if interesting.
     
  5. Jan 18, 2023 at 8:19 PM
    #5
    Jack McCarthy

    Jack McCarthy Navigating the luminiferous ether to see the light

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    This seems like one of those problems where you need to look at the FSM and find which points to probe with a multimeter to see if the signal is getting to the transfer case actuator.
     
    shifty` likes this.
  6. Jan 18, 2023 at 9:46 PM
    #6
    daveeasa

    daveeasa FBC Harness Solutions

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    And/or might be worth a dealer eval? If time is money? If short on money and long on time, ignore me.

    Dealer helped me identify a self induced problem with scangauge and a pinched cable. I was happy to shell out a couple hundo for the assist even though it was entirely my f-up. Because I'd rather have it fixed than not fixed for that price.

    Just a random idea.

    I see the college kid thing, and I get it. I was young once so I get it.
    A "good" dealer is going to be willing to do a basic eval without breaking the bank and might zero in on the root cause. I've had pretty decent experiences with two different dealers. It can happen. And in my book, it's money well spent because it's more fun to have working s than broken s, right?

    Now, if the dealer wants 1500 to replace a water pump, you are entitled to tell them to f off b/c that's s you can do yourself with adequate time and patience.

    But for diag stuff, sometimes they have access to knowledge/resources/tech that we don't. Hence it might be something to consider throwing 100-200 at for the diag side. Most dealers will stop there and ask if you want to proceed with a recommended fix. And if swapping the ECU is the right call, that's when you can take over and start the parts search.
     
    Last edited: Jan 18, 2023
  7. Jan 19, 2023 at 2:28 AM
    #7
    w666

    w666 D. None of the above

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    Everything you need to know is probably herein:

     
    Jack McCarthy likes this.
  8. Jan 19, 2023 at 5:18 AM
    #8
    N84434

    N84434 In the Frozen Tundra

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    I would verify that the T case actuator is in fact in the correct 2HI position when you have initially selected 2HI and the ADD is not engaged. It's possible that the 2 actuators are out of sync, but with the ADD actuator engaging, it could very well be a wiring or ECU problem. The truck is in 2 wheel drive mode currently??
     
    NickB_01TRD and Jack McCarthy like this.
  9. Jan 19, 2023 at 7:29 AM
    #9
    FiatRunner

    FiatRunner New Member

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    Neither the transfer case actuator or the front axle actuator work on my truck.

    However, when I press the button, I can see the voltage drop on the gauge for a few seconds as it tries to shift. Thus, I know that power is getting to somewhere, likely the actuators, as load is being applied to the alternator.

    Do you see the voltage drop when the button is presses?
     
  10. Jan 22, 2023 at 6:13 PM
    #10
    Mhagha

    Mhagha New Member

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    I couldn’t get my 4x4 to work. Someone told me to drive in reverse for like 20 feet…. Then it worked.
     
  11. Jan 23, 2023 at 10:15 AM
    #11
    RHP

    RHP [OP] New Member

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    Thanks to all for replying! I had watched a youtube video of someones early 2000's tacoma. They use the same actuators as the tundras. Figured out that the shaft the actuator motor moves was stuck in 4hi. Had to re-time the new actuator, mechanics say this can't be done without disassembling the t-case, but I was able to do it by taking the plastic cap off of the actuator and turning the gear with the three prongs so it lines up in 4hi. I put it back on and it worked! had to make sure that I bolted the actuator on before putting the little gear into the actuator. (I'll include the video link).
    Now My 4hi light is no longer flashing and I can hear the t-case actuator engage, and lights on dash are normal. Now I believe that its just my ADD actuator is bad! Very happy that I was able to time it correctly because bringing it in would have cost an arm and a leg.

    Video to replacing and timing the actuator
    https://youtu.be/_retFUemr_g
     
    N84434, shifty`, w666 and 1 other person like this.
  12. Jan 23, 2023 at 11:23 AM
    #12
    shifty`

    shifty` I might be an adult, I'm a minor at heart

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    Awesome, glad you posted this one. Who knows who else it may help down the road.

    I wish there was a full-on '4WD for dummies' for this specific generation. Someone that walks you through the guts of how everything plays together. It's one of the things I really don't have a good mental picture of.
     
    w666 likes this.
  13. Jan 23, 2023 at 11:49 AM
    #13
    Jack McCarthy

    Jack McCarthy Navigating the luminiferous ether to see the light

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    So the 4wd front driveshaft is now spinning but you're unable to get the front diff ADD actuator to engage? How did you confirm you're not in 4WD? Does the 4WD dash light stay on or does it even come on at all now that it's not flashing?

    Glad you got the transfer case actuator working. I remember someone here saying something as simple as banging on it made it come loose for them.
     
  14. Jan 23, 2023 at 12:01 PM
    #14
    shifty`

    shifty` I might be an adult, I'm a minor at heart

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    I've read on here things as simple as throwing in reverse has worked also to free things up.
     
    Jack McCarthy[QUOTED] likes this.
  15. Jan 23, 2023 at 12:34 PM
    #15
    w666

    w666 D. None of the above

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    Not Gen 1 specific, but...




     
    shifty`[QUOTED] likes this.
  16. Jan 23, 2023 at 1:24 PM
    #16
    shifty`

    shifty` I might be an adult, I'm a minor at heart

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    Yup. I think I watched that within the last couple years. But I was thinking more Gen1-specific, since things change a lot over the years.
     

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