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Blinking 4x4 Light 2nd Gen, Checked many things no luck

Discussion in 'Technical Chat' started by TheMuffinMan, Oct 8, 2019.

  1. Oct 8, 2019 at 8:29 PM
    #1
    TheMuffinMan

    TheMuffinMan [OP] Banana Nut

    Joined:
    Dec 10, 2013
    Member:
    #118280
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    2,370
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    Male
    Coeur d'Alene, ID
    Vehicle:
    2023 Tundra Limited Crewmax 6.5' 4x4
    So I have the dreaded blinking 4x4 light that doesn't engage when I shift from 2HI to 4HI. When in 2HI the light does not blink. I have a 2014 4.0, 6MT SR5 without the off-road package, with 101k miles on the clock. For background I know basic circuits, limited mechanical knowledge (have rebuilt my dirt bike engine, etc) and am not afraid of a multimeter. I dove into this in a roundabout way for various reasons but the order of things I did after doing a bunch of research on TW and the internet:

    Order of things:
    1. Removed front ADD and soldered motor connections, inside looked spotless, traces looked good. No signs of arcing on the motor contacts. Put it back on and the blinking continues.

    2. Looked at the transfer case actuator. Ended up taking the actuator off and apart and it looked really good inside, no corrosion. The motor looked good too, brushes looked fine. Read a bunch and finally figured out how to re-time it, and made sure the t-case was in 2HI before reinstalling. Tested all the positions of the actuator on the bench electrically to verify they matched the wiring diagrams I've found. I did find the 4WD position switch was bad so I replaced that. Wiggled the actuator back on the truck and still just the blinking light.

    3. Tested the t-case actuator motor and position switches after the one was replaced and they are reading properly and the shift shaft moves easily from 2HI -> 4HI -> 4LO and in reverse by using a small 12v battery. Verified by hearing the thunk as it clicks in and out and rotating the driveshaft to watch the front propeller shaft rate of rotation.

    4. Tested the ADD and it too moves freely both ways with the battery.

    5. Took the ADD off again thinking I messed up the timing since I was getting readings that weren't compatible with the wiring diagrams. Pin 4 (ground) would have continuity to 6 (2WD) but it never turned off when there was continuity to pins 3 and 5 (position switch and 4WD respectively). Well after monkeying with the internals for a few hours I never was able to get it in a position where pin 3 and 5 would have continuity to ground when 6 would not. So in frustration I ordered a new ADD from Rock Auto. It came in 4WD position, I plugged it in to the wiring harness without installing the ADD in the truck and turned on the truck (which is set to 2HI) and the ADD moved to 2WD position. Reinstalled the new ADD on the truck making sure the shift fork was on the sleeve and nothing, still just a blinking 4x4 light.

    I'm going out of town for business for the next few days but is there anything I'm missing? My next step when I get back is to figure out where the 4x4 ECU is and start testing pins and checking voltages as the various service manuals state. It's either the ECU or t-case actuator at this point and I verified the t-case actuator works but I highly doubt it's the ECU.

    But is there anything else I should check after I get back from my business trip?

    The biggest bitch of this whole thing: I paid off the truck 4 days before I discovered the 4x4 wouldn't work.... Ah well, more money to fix it!

    No other issues in 101k miles though besides a squeaky clutch pedal.
     
  2. Oct 11, 2019 at 9:15 AM
    #2
    stu8319

    stu8319 Well-Known Member

    Joined:
    Sep 18, 2018
    Member:
    #266652
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    First Name:
    Stuart
    Oklahoma City
    Vehicle:
    2018 Tacoma TRD Off-Road in Quicksand
    I kind of scanned this, but have you tried putting it in 4HI and driving around in a grassy field or something? Try some figure 8s, drive in reverse a bit. My friends 3rd gen 4 runner did something similar and it just needed some movement really.
     
    TheMuffinMan[OP] likes this.
  3. Oct 11, 2019 at 8:44 PM
    #3
    Ricardowelch

    Ricardowelch Member

    Joined:
    Sep 18, 2019
    Member:
    #305620
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    Male
    Sorry for hearing your issue. You can refer this link if it helps or not. Good luck.
    https://www.tacomaworld.com/threads/4-wheel-drive-blinking-indicator-light.197091/
     

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