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How To Trouble Shoot 4x4 Actuator

Discussion in '2nd Gen. Tacomas (2005-2015)' started by blackhawke88, Feb 15, 2013.

  1. Jun 8, 2020 at 9:15 AM
    #661
    Heineken

    Heineken Member

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    I took some voltage readings at the 4WD ECU. It is definitely getting power, and most of the voltage readings are in the correct range according to the attached diagnostics document (Pg TF-47).
    I started on the top of the list with Terminal 12 to body ground: < 1 Ohm
    Terminal 11 to 12: 12.42 volts

    For the next two I wasn't sure if I was supposed to apply direct power to front ADD to get it in these positions or not. I did not do this but simply checked to see if the voltage changed when the 4WD dash switch was changed from 2Hi to 4HI position.

    terminal 18 to 12: 12.13 volts, did change when switch was changed
    terminal 19 to 12: 12.13 volts, did NOT change with switch position

    terminal 25 to 12: Dash switch in 4LO (12.25 volts), in 4HI (0.67 volts), in 2HI (0 volts)
    terminal 26 to 12: 9.91 volts (did not test while driving)
    **terminal 28 to 12: This fluctuated continuously from 3.57 volts to 9.91 volts. When the key is first turned to on position it spikes at 11.5 volts.
    **terminal 32 to 12: 4HI (0.67 volts), in 2HI (12.14 volts). Forgot to write down what it did in 4LO, but it is already very low voltage in 4H which does not correlate with diagnostics document.

    For what it is worth I went to a salvage yard and swapped out the 4wd ECU to see if it changed anything. The 4WD and 4LO lights still blinked continuously when key was turned to ON position. Not sure if a different ECU would have to be calibrated to the vehicle first or not, any thoughts?

    About to take it to the dealer to have them run through everything and see what they come up with. Any further advice before I do?

    Thanks!
     

    Attached Files:

  2. Jun 16, 2020 at 8:40 AM
    #662
    Heineken

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    Had the dealer check the ECU and test for shorts in the wire harnesses. Tech said the limit switches for the transfer case actuator are either damaged or need re-timed. Recommended replacing the entire T-case actuator (Estimate around $2k). Any Input on how to ensure the timing on the limit switches is correct? Thanks
     
  3. Jun 16, 2020 at 8:51 AM
    #663
    uurx

    uurx Well-Known Member

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    just ask them for a written guarantee that states if this 2k worth of repairs does not fix the problem you want full reimbursement
     
  4. Jun 16, 2020 at 9:14 AM
    #664
    Heineken

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    I have strong doubts that the limit switches are damaged. I want to get everything into the correct position so that the ECU stops causing the flashing 4WD And 4LO lights. But I need to know the best method to do so, and whether to start at the t-case actuator or the ADD actuator. I’m not willing to spend 2K for a potential fix, I would just upgrade to an FJ Tcase at that point.
     
    dborrer and uurx like this.
  5. Jun 16, 2020 at 9:27 AM
    #665
    uurx

    uurx Well-Known Member

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    my .02, start at the ADD

    all of my issues have seem to have been ADD related

    i know how you feel though, this is beyond frustrating to diagnose
     
  6. Jun 16, 2020 at 3:30 PM
    #666
    Heineken

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    Update for ECU testing:

    I tested the TL1, TL2, and TL3 terminals in the ECU, which should correspond with the limit switch positions in the transfercase actuator. All had readings of 12.6 volts, which contradicts what should be occurring, at least according to the 4wd troubleshooting PDF I posted earlier. I tested the terminals at the transfercase actuator, and they were demonstrating the proper readings for the 2Hi position (continuity for the appropriate pin, no continuity for the other two pins). Does this suggest a problem with the ECU? Starting to bang my head against the wall from this problem, as a dealer tech I spoke with could not give me solid answers. Thanks for the help.
     
  7. Jun 17, 2020 at 8:50 AM
    #667
    6 gearT444E

    6 gearT444E CEO & CFO @BPF

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    TL1 should be reading 0 volts in 2hi. Sounds like your actuator limit switch is toast, you can replace that fairly easy, unfortunately no aftermarket solutions, your best bet is to find a junker and swap it out. Please see attached for some additional references. Should be pretty simple, take all the readings, see what doesn't match. The t-case actuator engages first followed by the front ADD actuator. The 4hi position switch on the t-case is what tells the front ADD to engage, so if that's bad, you won't get the ADD to ever attempt to lock in.
     

    Attached Files:

  8. Jun 17, 2020 at 10:33 AM
    #668
    Heineken

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    That was my first thought, however I just replaced the Tcase actuator with one I found at a salvage yard. I ensured that the limit switches were in the correct position, and I even tested them in multiple positions to make sure they were reading as they should. I tested them at the pins on the Tcase actuator with it out of the truck and also while installed.

    Is it possible that either a short is occurring in the wiring harness, or even that the ECU is bad? Any recommendations for testing the ECU? If I install an ECU that I salvaged, does it have to be calibrated?

    I am posting from my phone, so if that info is in the attached docs you provided I apologize. Will read them thoroughly after work. Thanks for the info!
     
  9. Jun 17, 2020 at 10:53 AM
    #669
    6 gearT444E

    6 gearT444E CEO & CFO @BPF

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    Interesting, well there is a thought then that a pin on one of the connectors that goes into the t-case actuator and/or 4wd ECU could be loose or disconnected, or the wiring in between the two connectors are frayed somewhere.

    No testing procedure for the ECU but if you verify the voltages are all good feeding back to the ECU, then that would be your last failure mode you could replace it. The ECU is readily available and in my experience almost is never the problem. It does not have to be calibrated, if you need one I have one I can sell for cheap. They are a very simple device, a couple relays and transistors that switch on and off the motors.
     
  10. Jun 17, 2020 at 3:16 PM
    #670
    Heineken

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    Thanks for the info. Are there different versions of the 4WD ECU and do I have to ensure it is compatible prior to switching out? I'm going to double check the wiring when I have a day off, which is not this week. Depending on the cost I may just buy the ECU from you and replace it to see if that resolves the issue, before crawling around and testing all the wiring harnesses. Let me know a price, thanks again.
     
  11. Jun 17, 2020 at 3:37 PM
    #671
    Heineken

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    I have an additional follow up question. So when I tested the TL1, TL2, and TL3 wires at the ECU, I tested them with the wiring harness attached to the ECU. All had voltage readings about 12 volts. I removed the wiring harness from the ECU, but left the other wiring harness attached (the one that supplies the power and ground to the ECU). I tested the appropriate pins in the ECU for TL1, TL2, and TL3 (while the wiring harness was disconnected), and they all read above 12 volts. I repeated both of these tests after unplugging the wiring harness to the Transfer case actuator, and all results were the same. Does this point to a problem in any specific area? Thanks
     
  12. Jun 17, 2020 at 9:23 PM
    #672
    6 gearT444E

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    I don't believe that is a valid test. 12V is sent to each of the TL1, TL2, and TL3 pins all the time, once those limit switches make up in the appropriate position (2wd, 4wd, 4lo respectively), they send that 12V to ground, the ground is supplied through the transfer case actuator harness. That in turn signals the 4wd ECU logic that the limit switch has changed position. Doing the test with the harness unplugged will give you erroneous results. You want to do the voltage tests just as the truck is performing normally with all the harnesses connected. Get a DVM with long pointy leads like the one in this picture, or use a paperclip to probe the back of the connector to get a voltage reading while the connector is still in the ECU.

    81crOYs7FpL._SL1500_.jpg

    I believe there are differences, for example if you have an elocker or not. Mine is out of a 2010 TRD offroad it's actually still in my truck. I installed an FJ case many moons ago due to my transfer case actuator taking a crap, send me a PM and let me know I can probably get a P/N off it if I remove it from the truck, and you can check to make sure it will work for yours.
     
  13. Jun 29, 2020 at 10:03 AM
    #673
    Nelson_2430

    Nelson_2430 Member

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    Hi all-

    ive been following along trying to troubleshoot the same symptoms as Heineken:

    wont switch out of 2wd, 4hi light on constant, 4lo light blinks constant, beeps if dial is switched out of 2hi

    i just had it back from the dealer, they told me the front actuator is bad(i took it in for the frame spray so had them run diagnostics while it was there).
    prior to taking it in to the dealer, i pulled the ADD(bench tested) and did the solder fixed that has solved it for many others with no luck

    i have now ordered a new ADD to replace it. does anybody know what the OEM part number is?

    i am at a loss and i am not convinced a new actuator will fix it.

    i will report back once i swap it out, if it doesnt work i will move to the next thing i guess
     
  14. Jun 29, 2020 at 11:04 AM
    #674
    6 gearT444E

    6 gearT444E CEO & CFO @BPF

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    41400-35032

    Good luck
     
  15. Jun 30, 2020 at 8:58 AM
    #675
    Nelson_2430

    Nelson_2430 Member

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    @6 gearT444E


    thanks for your response. i got the new actuator and i was going to solder the leads for some preventative maintenance.
    one question i had was we re-assembling the unit...is there any trick to it? there is a little switch opposite the motor...where does that get lined up? can i put it back together incorrectly?


    any help would be great

    thanks in advance for your time
     
  16. Jun 30, 2020 at 11:41 AM
    #676
    6 gearT444E

    6 gearT444E CEO & CFO @BPF

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    that’s the switch to let the 4wd ECU know the ADD is engaged. It’s actuated by a cam on the gear drive. As long as you take it apart and put it back together without moving the worm gear it shouldn’t require any tinkering with.
     
  17. Jun 30, 2020 at 11:45 AM
    #677
    Nelson_2430

    Nelson_2430 Member

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    i think i moved the worm gear (mad at myself!)

    if its in 2hi currently... should the arm be all the way to the motor side or to the breather hose side?

    looks like i only have clearance to drop the cam below the switch if the fork is halfway through its travel...does that make sense?
     

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