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

4wd System Operation & Help Thread

Discussion in '2nd Gen. Tacomas (2005-2015)' started by Dm93, Oct 27, 2021.

  1. Oct 25, 2023 at 8:02 AM
    #741
    cwjmopar

    cwjmopar Member

    Joined:
    Oct 24, 2023
    Member:
    #436140
    Messages:
    6
    Gender:
    Male
    First Name:
    Carl
    Post #5 only has .23 volts
     
  2. Oct 27, 2023 at 4:29 AM
    #742
    BluntTaco

    BluntTaco Tight and Right

    Joined:
    Sep 25, 2011
    Member:
    #64091
    Messages:
    30
    Gender:
    Male
    First Name:
    Randy
    Centreville, MD
    Vehicle:
    09' Taco 4x4 TRD Sport
    Undercover, Pioneer AVIC Z130BT, Toyota Roof Rack, Drop in aFe. Camburg UCA's, Toytec Ultimate 5100 Kit, OME Dakar Rear Kit, Custom Mayhem Grill, Wicked Muff w/tip, Some Debadging.
    Cruise works, no codes thrown. All the fuses look good. It’s weird I came back from vacation and these are just flashing, never tried put it in 4wd. Is it possible the ECM went up? No clicking when I try to engage 4wd. I do live in a rural area with mice but I don’t see any chewed wires but I also don’t really know where to look. Thanks
     
  3. Oct 27, 2023 at 5:53 AM
    #743
    Dm93

    Dm93 [OP] Test Don't Guess

    Joined:
    Mar 3, 2015
    Member:
    #150066
    Messages:
    12,324
    Gender:
    Male
    Texas
    Vehicle:
    2014 DC OR 6spd 4x4
    Predator tube steps, Ranch Hand grill guard, Magnaflow CatBack exhaust, Toyota tool box & bed mat, 2LO Module by @Up2NoGood, Rearview Compass/Temp Mirror, Tune by @JustDSM.
    I mean if you can't find anything obvious do the voltage checks at the 4wd ECU and post your results.
     
    TnShooter likes this.
  4. Nov 7, 2023 at 3:14 PM
    #744
    JoeKeepsTruckin

    JoeKeepsTruckin Member

    Joined:
    May 7, 2020
    Member:
    #327234
    Messages:
    21
    Gender:
    Male
    First Name:
    Jorel
    Vehicle:
    2015 DCSB TRD Off Road
    Bone Stock
    Back after a short hiatus, pretty embarassed. I was checking the wrong circuit B2 (ground?) instead of B26 for the ADD 4WD, and basically getting a false negative. In my defense the printout table in the first post on this thread does have a typo. So I was led astray, replaced the ADD and after rechecking now, it looks like the 4WD switch in the transfer case actuator actually might be the problem. I checked the continuity on all 6 pins from connectors to ECU for the ADD and they're all good.

    I rolled the truck back and forth on this test when in 4HI, to see if anything broke loose. Front driveshaft is definitely engaged since I cant turn it by hand, but the voltage on the 4WD switch says it's not engaged, so maybe it's a faulty switch, or something is gummed up in the TC actuator?

    Kinda funny the default state in 2WD is 12v, and when the switch gets activated by the trasfer case mechanism going to 4WD it goes to 0v, or an "open" circuit... again my electrical knowhow is pedestrian at best. Probably a method to the madness.

    Anybody know the troubleshooting procedure for the 4WD switch? Connections and continuity are good to the ECU, looks clean, but cant see the switch side from under the truck either.

    Results from last week's test in the right side of the write-in column, marked 10/29.

    4WD trouble shoot 10-29-23.jpg
     
  5. Nov 7, 2023 at 5:53 PM
    #745
    6 gearT444E

    6 gearT444E Certified Electron Pusher

    Joined:
    Feb 3, 2018
    Member:
    #243372
    Messages:
    7,721
    Deep South
    Herculiner Hootus
    upload_2023-11-7_20-52-14.png
     
  6. Nov 7, 2023 at 5:56 PM
    #746
    JoeKeepsTruckin

    JoeKeepsTruckin Member

    Joined:
    May 7, 2020
    Member:
    #327234
    Messages:
    21
    Gender:
    Male
    First Name:
    Jorel
    Vehicle:
    2015 DCSB TRD Off Road
    Bone Stock
    Thanks, but I meant the 4wd switch within the transfer case actuator.

    I havent' pulled the dash 4WD switch but seems like if it wasn't working neither the transfer case nor front diff ADD would engage...but probably a few permutations of behavior there.
     
  7. Nov 7, 2023 at 6:42 PM
    #747
    TnShooter

    TnShooter The TacomaWorld Stray

    Joined:
    Sep 2, 2010
    Member:
    #42625
    Messages:
    20,598
    Gender:
    Male
    First Name:
    Deogee
    Vehicle:
    07' TRD Off-Road, Auto
    STOCK
    Your actual switch on the dash is fine. Because your 2-4and LO voltages are correct.
    Your DL1 wire is being pulled (shorted) to ground. Either by corrosion in the actuator or a bad wire touching body ground.
     
  8. Nov 7, 2023 at 6:45 PM
    #748
    Dm93

    Dm93 [OP] Test Don't Guess

    Joined:
    Mar 3, 2015
    Member:
    #150066
    Messages:
    12,324
    Gender:
    Male
    Texas
    Vehicle:
    2014 DC OR 6spd 4x4
    Predator tube steps, Ranch Hand grill guard, Magnaflow CatBack exhaust, Toyota tool box & bed mat, 2LO Module by @Up2NoGood, Rearview Compass/Temp Mirror, Tune by @JustDSM.
    Yea I apologize for the typo, we just recently caught it and I fixed it. It was only on the printable chart I made but has since been fixed.


    So it looks like a faulty switch then, just to verify circuit integrity you can jump the 2 terminals at the switch and make sure B22 at the 4wd ECU goes to 0v.

    The switch is open in 2H and closes when the Transfer Case shift rod is in 4wd, this pulls the circuit to ground (0v).

    The switch is pretty easy to access, it is screwed into the Transfer Case Actuator (the one closest to the transfer case). Pretty easy to test, with the switch depressed there should be continuity between the terminals.
    Transfer Case Actuator Schematic (4wd Switch).jpg
     
  9. Nov 7, 2023 at 6:49 PM
    #749
    JoeKeepsTruckin

    JoeKeepsTruckin Member

    Joined:
    May 7, 2020
    Member:
    #327234
    Messages:
    21
    Gender:
    Male
    First Name:
    Jorel
    Vehicle:
    2015 DCSB TRD Off Road
    Bone Stock
    @Dm93 my man, good call, thank you. I thought it looked like the switch could be removed from the diagram but didn't want to fuck around and find out. I dont want to pull the TC actuator if I dont have to.

    Ill see if I can get under there in the next couple days and verify 0v with a jumper and then pull the switch to test it.
     
  10. Nov 7, 2023 at 6:55 PM
    #750
    TnShooter

    TnShooter The TacomaWorld Stray

    Joined:
    Sep 2, 2010
    Member:
    #42625
    Messages:
    20,598
    Gender:
    Male
    First Name:
    Deogee
    Vehicle:
    07' TRD Off-Road, Auto
    STOCK
    @Dm93 Curios as to why the voltages say he is in 2WD.
    Yet the front driveshaft will not spin?
     
  11. Nov 7, 2023 at 7:03 PM
    #751
    JoeKeepsTruckin

    JoeKeepsTruckin Member

    Joined:
    May 7, 2020
    Member:
    #327234
    Messages:
    21
    Gender:
    Male
    First Name:
    Jorel
    Vehicle:
    2015 DCSB TRD Off Road
    Bone Stock
    I edited the photo to clarify and add some color. I believe the TC actuator switch is implicated because the B22 circuit is reading incorrectly, so the ECU wont switch the ADD to ENGAGED because the 4WD switch in the TC actuator never tells the ECU it's actually in 4WD. TC is engaged but the computer doesn't know it because of the (possibly) faulty switch.

    upload_2023-11-7_19-2-36.png
     
    Dm93[OP] likes this.
  12. Nov 7, 2023 at 7:05 PM
    #752
    TnShooter

    TnShooter The TacomaWorld Stray

    Joined:
    Sep 2, 2010
    Member:
    #42625
    Messages:
    20,598
    Gender:
    Male
    First Name:
    Deogee
    Vehicle:
    07' TRD Off-Road, Auto
    STOCK
    That is also how I'm reading it.
    I don't think the 4WD switch is bad.
    You have an ADD issue.
    As the ADD says you are in 2WD
     
  13. Nov 7, 2023 at 7:05 PM
    #753
    Dm93

    Dm93 [OP] Test Don't Guess

    Joined:
    Mar 3, 2015
    Member:
    #150066
    Messages:
    12,324
    Gender:
    Male
    Texas
    Vehicle:
    2014 DC OR 6spd 4x4
    Predator tube steps, Ranch Hand grill guard, Magnaflow CatBack exhaust, Toyota tool box & bed mat, 2LO Module by @Up2NoGood, Rearview Compass/Temp Mirror, Tune by @JustDSM.
    Well either the Transfer Case is in 4wd or the ADD is locked in, only way to tell which is locked in is to jack up the front end and spin the wheels.
    The 4wd detection switch is next in the sequence of operation so makes sense to start there.
     
    TnShooter[QUOTED] likes this.
  14. Nov 7, 2023 at 7:08 PM
    #754
    TnShooter

    TnShooter The TacomaWorld Stray

    Joined:
    Sep 2, 2010
    Member:
    #42625
    Messages:
    20,598
    Gender:
    Male
    First Name:
    Deogee
    Vehicle:
    07' TRD Off-Road, Auto
    STOCK
    Yeah, The ADD reports he is in 2WD.
     
  15. Nov 7, 2023 at 7:54 PM
    #755
    JoeKeepsTruckin

    JoeKeepsTruckin Member

    Joined:
    May 7, 2020
    Member:
    #327234
    Messages:
    21
    Gender:
    Male
    First Name:
    Jorel
    Vehicle:
    2015 DCSB TRD Off Road
    Bone Stock
    From Dm93's background provided on this thread and other troubleshooting resources, I understand there's an order of operation the 4WD ECU goes through when switching 2WD>4HI>4LO and back.
    The ECU only tells the front diff to engage the ADD after the TC is confirmed in 4WD, which requires the (B22) switch to close to ground and read 0v.

    It would be insane if the ADD were bad since I thought that was the problem in the first place and replaced the damn thing and now recently checked all the circuits again - all have continuity to the ECU pins and voltages are reading correctly in 2WD. I feel like jacking the damn thing up is overkill but I can just to prove the point / verify.

    Ill be sure to report back on my findings of course :thumbsup:
     
    TnShooter and Dm93[OP] like this.
  16. Nov 7, 2023 at 8:14 PM
    #756
    Dm93

    Dm93 [OP] Test Don't Guess

    Joined:
    Mar 3, 2015
    Member:
    #150066
    Messages:
    12,324
    Gender:
    Male
    Texas
    Vehicle:
    2014 DC OR 6spd 4x4
    Predator tube steps, Ranch Hand grill guard, Magnaflow CatBack exhaust, Toyota tool box & bed mat, 2LO Module by @Up2NoGood, Rearview Compass/Temp Mirror, Tune by @JustDSM.
    That is correct.

    I wish we had caught my typo sooner so we weren't chasing our tail on the ADD:anonymous: but I think we are on the right track now.
     
  17. Nov 7, 2023 at 8:36 PM
    #757
    TnShooter

    TnShooter The TacomaWorld Stray

    Joined:
    Sep 2, 2010
    Member:
    #42625
    Messages:
    20,598
    Gender:
    Male
    First Name:
    Deogee
    Vehicle:
    07' TRD Off-Road, Auto
    STOCK
    No. What’s insane is the rate at which new parts are bad out of the box.
    Let alone going bad shortly after replacement. Parts quality has gone down a lot in the last few years.
     
    Williston and Dm93[OP] like this.
  18. Dec 12, 2023 at 8:26 PM
    #758
    Dm93

    Dm93 [OP] Test Don't Guess

    Joined:
    Mar 3, 2015
    Member:
    #150066
    Messages:
    12,324
    Gender:
    Male
    Texas
    Vehicle:
    2014 DC OR 6spd 4x4
    Predator tube steps, Ranch Hand grill guard, Magnaflow CatBack exhaust, Toyota tool box & bed mat, 2LO Module by @Up2NoGood, Rearview Compass/Temp Mirror, Tune by @JustDSM.
    I just completed a new project, I've pretty much fully emulated the 4wd system in a tabletop setup so that I can plug in various faults and see how the system reacts.

    Thanks to @DesertRatliff for the 4wd ECU, switch, & pigtails.

    A few pictures and video clip of it in action.
    Top row of switches can be used to create an open circuit and bottom row can create a short on each of the limit switch circuits.
    4wd, L4, & ADD detection switches I just used a single switch instead of making 2 more cams to drive them.
    Wiring is kind of a mess but I wasn't really going for looks as much as making it all work.

    ABLVV86tp_G4wnHTZLWipV5oetqeWIZrudB_AvRf_6d67f7f96be1680152fe9892025626e9ff800ce1.jpg

    ABLVV85Lbc1dDyvUpPzTlPwSOlIUVh7AVIzQfk13_ce9bcbfe08df156cf7bb2074de163c39b134cc1e.jpg

    ABLVV87Rji1QCGDpx00ubimf1zMr0tauiMSYbeTP_467a69a9a8cd808f56e5465a87b74b1b8c7668be.jpg


    https://www.youtube.com/shorts/zZsoEXl4Xls?feature=share
     
  19. Dec 12, 2023 at 8:52 PM
    #759
    TnShooter

    TnShooter The TacomaWorld Stray

    Joined:
    Sep 2, 2010
    Member:
    #42625
    Messages:
    20,598
    Gender:
    Male
    First Name:
    Deogee
    Vehicle:
    07' TRD Off-Road, Auto
    STOCK
    Talk about going over and above.
    I can’t say I know many people willing to reverse engineer a 4WD system.
    By the time this thread is finished we should know all there is to know about the system.
     
    Williston and Dm93[QUOTED][OP] like this.
  20. Jan 6, 2024 at 8:17 PM
    #760
    Griff768

    Griff768 Member

    Joined:
    Oct 2, 2020
    Member:
    #342617
    Messages:
    7
    Gender:
    Male
    So I've been fighting this for a few years off an on. Thrown a buncha parts at it. As soon as the key gets turned on 4Hi and 4lo lights flash constantly. The only time they ever stopped is when i unplugged the 4wd computer. Truck was always in 2wd unless i manually turned TC actuator gear and powered 12v to front actuator to lock it if 4x4 was needed. Lately i bought backprobe pins and printed off all the troubleshooting info in this thread. This helped alot. I had a 4wd switch on the transfer case that tested ok but not all the time. I swapped that out with a good spare and now it tests good. After i did that i tested all the 2H voltages and they were all good except dl2 was going to ground 0V. Tonight i did more testing and retimed my front ADD probe positions. This fixed the Dl2 voltage now shows 11.5v. All voltages now show expected values however both lights still flashing. I tried Key off- key on. key off open close door key on. Let truck sit 1/2 hr. I tried going for a short drive and coming back and parking still no change. The only thing that might have happened is it seems the lights take a extra half second to start flashing now. Just wondering if there is anyway to reset the system, or if you think its worth it to manually position everything in 4wd all actuators and the dash switch then try starting truck. Thanks for all your work making this thread and any suggestions you have in solving this. So far i have at one point or another over the years changed out the dash switch, 2 front actuators, TC actuator, used Tcase with another actuator, all with zero change just constant flashing lights. Making one last attempt to actually trouble shoot it and if i cant figure it out FJ swap TCase it is. Ill be working all day tomorrow so might not reply till tomorrow night
     

Products Discussed in

To Top