4WD Actuator Troubleshooting (Transfer Case and ADD)

The following data is being centrally located to assist people in troubleshooting issues in the 4WD actuator system in 3rd Gen. If you are having issues and want assistance, please create a new thread and link to this one as required, it keeps it easier to prevent confusion to have each truck/issue as its own thread.


4WD System
The 4WD system consists of a transfer case directly after the engine, and a front Automatic Differential Disconnect (ADD).

Transfer Case
The transfer case connects the front drive axle to the rear drive axle when activated, as well as providing reduction gearing when activated in low gearing. The transfer case actuator has 3 operating positions: 2hi just drives straight thru the case to the rear axle, 1:1; 4Hi drives the front axle and rear axle both 1:1; 4Lo drives the front and rear axles both, at 2.57:1.

Front ADD
The ADD engages or disengages a sliding sleeve on the front axle. It has 2 operating positions, Unlocked in 2Hi; Locked in 4hi or 4Lo.

ECU Checks
Each Actuator contains a motor and position feedback wipers. On engine start, and on each requested 4WD mode change, the system checks each actuator for motor resistance, and that the position feedback wipers are giving a position that is an acceptable position. (It doesn’t have to be the desired position, just an acceptable position). If the resistance and feedback are ok, the ECU will drive the actuators to the desired position. If resistance or position sensors are not expected at startup or any mode change requests, ECU will throw a code and prevent further mode changes, leaving the system in the present position. Techstream is the first most ideal tool for troubleshooting, as it gives exact data on what data the ECU is receiving. If Techstream isn’t available the OBDII code can still help. All else fails, the following procedures are recommended.

Ohmmeter ADD checks
The easiest location to access the ADD is at the front axle after removing the transmission cover. Picture shown is truck side of the actuator, start by testing the actuator side. Pin numbering is opposite. The ADD has 6 wires. Pin 4 is normally grounded on the truck side, position wipers attach to pin 3,5,6. Pin 1 and Pin 2 provide motor power. Pins 1 and 2 should read approximately 5 ohms (1.5 ohm to 10 ohm per repair manual). Pins 3, 5, 6 to pin 4 should read per the following table.




Ohmmeter Transfer Case Checks
The transfer case connector has 12 pins, only 9 used. Shown connector is truck side, actuator side is opposite numbering right to left. Pin 6 and 10 is normally grounded on the truck side. Pin 1 and Pin 2 provide motor power. Pins 1 and 2 should read approximately 5 ohms (1.5 ohm to 10 ohm per repair manual). Pins 3, 4, 5 to pin 6, and pins 9,12 to pin 10 should read per the following table.
Pin 9 (L4 detection) is grounded to pin 10 when transfer case is in L4.
Pin 12 (4wd detection) is grounded to pin 10 when transfer case is in 4wd or L4




Known issues
On ADD, the actuator can be positioned into an invalid position (feedback not valid). This is only likely to occur in conjunction with bad actuator or wiring, or replacement of the actuator. To correct, manually drive the ADD motor to a mid position by applying 5V-9V or so to pin 1 and 2. The position feedback should then read a valid set. If not, then actuator feedback is indicated.

Manually operating the actuators
ADD
To go from 2wd to 4wd, 12v+ at pin 1
To go from 4wd to 2wd, 12v+ at pin 2
Transfer case
To go from

This can be cleaned up more, but start with something.

{Temporary Addition, Transfer Actuator Timing Video https://www.youtube.com/watch?v=GCY2BCdlU4I}

https://www.youtube.com/watch?v=GCY2BCdlU4I

 

Saving for Diff Lock Troubleshooting.

 

Any word on the diff lock troubleshooting? Since my 5.29s were installed I have an intermittent locker indicator flashing at start up. Last night when I put it in 4L I got the same indicator flashing (without me attempting to engage locker) and it wouldn’t lock up when I tried to engage.

After taking it out of 4L and putting it back into 4L the locker worked fine.

 

I have not read this for a while, but with the mention of TS and the SM, here are some shared links:

TS V14.20.019, which seems to work for all 3rd Gens including 2020s:
https://drive.google.com/open?id=1rHumlcFInkXdfAGgap0XS0KijFZumfSA
The same one as in my signature.

I tried to connect with a Bluetooth adapter and was not able. If someone knows how, that would be good info. At this time, TS is limited to USB adapters, like the Tactrix OpenPort adapter or the OVT version, as far as I know.


The incredible 2016 3rd Gen SM:
https://drive.google.com/open?id=1cx5nnlnCzlhI45D1vbBMj1ni983SKdKf

Note: The each section in included in the bookmarks.

Given the great work of the SM creator, hopefully someday someone will follow in their tracks to create an updated version.




If these links ever die, please let me know.

 

Recommend you start a new thread, reference this thread.

(However data you seek is probably
https://www.tacomaworld.com/threads/e-locker-failure.595826/

And

https://www.tacomaworld.com/threads...o-the-rear-differential.466594/#post-13979407


99% chance that the lock Switch was damaged during gear install. That switch cannot be easily replaced, I believe. Read thru those threads

 

Thanks! They actually did replace that switch and it did not help. I’ll start a new thread!

 

Maybe someone can help. I slowly lost the ability to get into 4hi or 4lo. I replaces the add with a new one, no change light just flashes. What is odd if I set the actuator to either To

go from 2wd to 4wd, 12v+ at pin 1
To go from 4wd to 2wd, 12v+ at pin 2

The truck blinks 4lo on startup. If I set the add to mid level using a 9v the 4lo goes away. Could it be a bad position sensor at the transfer case ?

 

Recommend you start a new thread, so doesnt get confusing... keep one truck per thread. (You can reference that you were trouble shooting per this thread.)
And explain when you encountered issue, when issue occurs, why you swapped add, etc

 

No problem

 

Thanks for the original post/ pin info. It helped me set the add to where it needed to be. I found what was the problem and my 4wd initiates better than when the truck was new. It was one part of the puzzle.

 

Hello I'm new here I own a toyota Hilux diesel with the same mechanism for 4x4 than Tacoma I change de front ADD actuator but I can't get timing in accordance with the actuator on transfer case, I tried to apply 9 volts to pin 1 and pin2 but I don't know how to do it the positive side of 9 volts is on pin 1 and negative on pin 2 or reverse or both pins needs 6 to 9 volts at the same time to get the front ADD on a position that ECU recognizes that it is ok.

My problem is that if I manually set the front ADD to unlock position everything works fine on 2H bit when I hit the selector to 4H the green light blinks and the 4x4H engages and works but immediately after that I get the message on the dash that de 2H to 4H have malfunction and visit your dealer then if I turn the selector to 2H it doesn't works back to 2H, stays on 4H, but I think that the problem is the timing but I don't know how to do it

 

I would prefer to keep each truck and issue in its own thread, but I will help here a bit... But I recommend starting a new thread, and reference this thread... describe what the original symptoms were, what you did (change out actuator) and why.

I have not looked at the Hilux schematic at all, so I will be speaking to the Tacoma 3rd gen schematic and assume its the same. I have not checked the P/Ns of the 4wd components on the Hilux to the Tacoma 3rd gen, so will assume they are similar.

In my experience, when the ADD is positioned in an unacceptable position, the truck will complain about the 4wd as soon as you turn the truck ignition ON. This is because the actuator feedback sent to the ECU truck is not one of the acceptable combinations (when its too far one direction or the other), so the truck doesn't know what to do. It doesn't matter what position the ADD is in, it just has to be an acceptable position. (if its locked, and the truck wants it unlocked, it will do that. If its in a middle position, it will move it as required.)


To get the ADD in an acceptable position, you just run it until its somewhere in the middle of the travel... hook the actuator and listen for its motor to run, (should take about 1.5 second count or so), then reverse the polarity and listen to it run the opposite way... the goal is to just leave the actuator in the middle of the travel (0.75 seconds if it takes 1.5 seconds to travel completely)… You just don't want the actuator driven completely either direction...


BUT, the symptoms you describe is a 99% chance that there is one (or more) bad feedback position wipers or wires (could be in the truck harness) on the transfer actuator or the ADD (in the 4wd system). This is highly likely if the truck seems to change in or out of 4wd (physically), but not will not change in the opposite direction happily. (this can be in the direction of engaging, or disengaging, it just depends on which wiper is not working.)

At this point, (if it was a 3rd gen Tacoma), the thing to do is get a copy of techstream, or use a multimeter to check the feedback sensors with a multimeter. It isn't that hard but it helps to be somewhat familiar with electrical troubleshooting.

 

Thank you very much I already started another thread for this problem that I have this weekend I'm going to put the actuator ADD on a correct position and see If I finally can solve this problem

 

Highly recommend using a 6V battery to drive front axle actuator. I used a deer feeder battery on pins 1 and 2 and it drove the motor at low power and a slower speed. This allowed me to get to get the right position. Side Note:With the low power 6V I had a way easier time than before when I used the 12V. With the help of this post I have finally and hopefully the whole 4x4 system working flawlessly. Hunting season will be the true test! Thanks Gents.

 

I had a flashing 4x4 and 4 lo light. I have found that the wires leaving the actuator are cracked and one is completely sheared. If I follow from the six prong connector to the first connection that is where the cracked wire is. Does anyone know what part number this wiring harness is?

 

I dont think you can find that PN in the customer-facing parts catalogs (that i have seen). That is one i would do junkyard....

 

I have an 07 4WD. When I engage into 4WD it'll click/pop as if it's engaging but nothing happens. If I go to 4LO I get the beeping. What could cause this and what do I need to fix it?

 

The man said to start a thread, and link to this thread.

https://www.ttguide.net/problem_symptoms_table-1469.html

 

I apologize BW, Stewart, are you allowing 60 seconds for it to switch?

I sometimes hear the engagement as well, and green blinking, but as soon as I give the Taco gas input, the 4WD icon lites up. It doesn’t happen a lot, but that’s what I learned to do. Sometimes leaving a foot in the brake and giving it a little blip of gas clicks and lites up the green icon.

 

Thank you for that video.

I miss manual lever-actuated differentials and hub locks even more now. It's nutball to let a computer do it for you.