06 Tacoma 4x4 no power to transfer case or diff actuators.

it is a Rube Goldberg operation for sure. All to move a front axle shift collar 1/2” and to move a transfer case shift rod about the same, so the soccer moms can keep tweeting on their phones while blogging about how great their wifi 4wd system is.

 

I thought about building a control panel with indicators and momentary toggles to run the transfer case shifter and just lock the front diff and leave it that way. I don't need 4wd that often but when I do I want it to work.

 

the problem is that it's not usually the ECU or switch that fails, it's the actuators that get water i them or get gummed up from not being used often. Putting in your own control switches would allow for easier diagnosis when things don't go right, since you will know where in the sequence something isn't working. Alot of people swap to the FJ cruiser transfer case to eliminate the electronics, myself included. I also eliminated the front actuator and just have the front axle shaft spinning all the time, so I don't have to worry about a 5 cent electronic failure occurring preventing me from using 4WD when I need it.

 

For the cost of a new actuator (t-case actuator is almost $500 and the front ADD is about $300) you can swap in the manual components and never have to worry again. Just a thought to keep in the back of your mind if it turns out one of your actuators is shot. I replaced mine twice before giving up on their poor reliability. If you need a new 4wd switch or 4x4 ECU let me know mine are still hanging around and in working condition.

https://www.rocksolidtoys.com/singl...iser-transfer-case-swap-into-05-Toyota-Tacoma

https://www.tacomaworld.com/threads/how-to-deleting-add-system.427258/

 

Others here have more experience with this problem than I, but in my way of thinking:
If both actuators work and they are getting no power, it is because the ECU thinks your already in or out of the desired 4x4 position.
I would verify the 2 position sensors work on the TC actuator.
If you don't find the problem there, I would take it to the local Dealer for a diagnosis (before throwing new parts on).

 

6I hate to get back on this thread looking like a dummy but I finally got to work on it again tonight but how do I identify the correct connectors on the ECU so I can check my specs? From what I read it's F12 &F13 which shows to be 6 pins across in row next to retainer clip. Mine are all 7 pin. Also the specs that 6 gear sent me are calling it a 4wd ecu but on the back of mine it says engine control. I've included a picture of what I have been looking at.

 

you need to look straight up from there. It’s above the glovebox. Only two plugs on it.

 

I found it and checked the voltage as per the specs you sent and it appears the ADD is what's giving the problem. Guess I'll have to drop the diff a little to get it where I can work on it. If I get the diff locked and unhook it is there any chance the ecu will let me go to H4 and back to H2 or is it a crapshoot to get anything to work? Rktman I did what you recommended and checked the position switches on the t/c. They were ok and I hot wired it to shift to L4. Hooked all switches up and actuator harness to see what would happen. Selector switch was in L4 position when I started the truck and everything worked as it should except front diff. When I switched to H2 it shifted as it should but would not shift back to H4 or L4. I've decided my biggest problem is the ADD. Guess I'll start on it after Thanksgiving. 6gear thanks for your help. If I eliminate the ADD will that force me to build my own switch to control the 4wd?

 

If its just the front actuator, it may be the motor contacts need a little soldering:

If you need a new one, Amazon or Rock Auto has the Dorman 600-488 actuator for around $200 (about 1/2 of Oreilly or Autozone for the same part.)

I found that a 1/4 ratchet, 6" extension, & wobble extension +12mm socket makes it easy to remove/install without dropping the diff.

 

The transfer case will look for feedback from the ADD limit switch when shifting back to H2 so if you force anything into position it will no longer function automatically. You can replace everything with a couple of DPDT switches and some common sense though.

 

Here is a schematic in which I drew to control the ADD using a simple DPDT switch, you can cut and splice into the existing 4wd ECU harness and wire to control it independently. Same theory can be had for the transfer case, most people just opt to swap in the FJ cruiser transfer case to rid themselves of the electronics.

 

I removed the ADD and couldn't see anything wrong other than a little corrosion on the motor. It still ran ok and limit switch contacts were in great shape so I sealed it up and reinstalled it. During the test my 4x4 light quit blinking and the shift in and out of 4x4 works as it should. Only problem now is it will not go in 4L. When trying it makes a chattering sound like antilock brakes do and with light pressure on the brake pedal there is a pulsation. I'm thinking I may have a problem with a speed sensor. A trip to a shop with a scanner is probably the best option. Very seldom would I ever need 4L but I want it to work. So far this whole ordeal has cost me nothing but my time and a few things I had on hand already. Now in H2 there is no light, in H4 it is on steady not blinking so I've just got one more to go. My thanks again to all who responded, it was valuable info to me.

 

just remember, the problem can be intermittent so just because you checked the voltage once and it worked doesn't mean it will work again the next time. Your best bet is something like an astromed or yokogawa data recorder and swap between 2 and 4wd multiple times to see where it hangs up each time to pinpoint the problem. The issue there is most folks would not want to dedicate that much time and/or money into troubleshooting and instead just buy new parts that yield the old shotgun affect. The good news as I said, was you can eliminate all the electronics for less than the cost of the transfer and differential actuators. Don't give into the Toyota electronic mind games.

The speed sensors are known to fail occasionally but I would not point that as a failure to shift into 4wd. Are you an auto or a manual? The manual gets its speed from the transfer case so if you have speed display on the cluster your speed sensor is working. If you are an automatic and have issues with wheel speed sensors (which generate their own trouble codes) you could have issues there, but the ECM generates a "speed signal" that is representative of the truck speed based on the number of operable sensors. Normally there are 4, there is algorithm built into the ECM to calculate the speed if a sensor or two were to fail.

 

I've had what sounds like road noise in the truck since I got it. Everyone who rode in it said it was tire noise but I thought it was a bearing. A Toyota mechanic said some sensors are a part of the hub bearings which would explain a possible failure if there is a bad brg. I have the a/t so that increases the possibility. Now that I understand more about how the system operates I don't think my actuators are the problem, it's getting the information to them so they know what to do. Both actuators work as designed when they get the right signal. I just need to locate the sensor giving the wrong signal or no signal at all. I do not believe in throwing money at a problem, I would much rather find the problem and fix it. Like I said earlier I'm retired and on a fixed income and have a hell of a lot more time than money plus I had much rather repair something than replace it. I've rebuilt a lot of starters, alternators, generators and even a few water pumps back in the day but nowadays they just go buy a new one. I guess I'm just too much old school. I won't be putting parts on till I am sure I need them.

 

I know this thread is a little stale...could be the front diff needle bearing though, i have the same thing and just replaced with the ECGS bushing...haven't gotten to test drive yet though because my front diff is empty and the truck is stuck in 4wd (separate issue).

 

Hey folks,
I am in a very similar boat as Cobra44. I have the m/t version, 2nd Gen Tacoma. I have no power to my transfer case motor.
I have replaced the tc motor once before, and it worked for a few months. I have inspected and tested both ADD and tc motors (both actuators) and they seem to work fine. During testing, I could hold the rear tc motors in my hand (disconnected from the vehicle), manually switch between 4wd positions, and the motor would move upon ignition to 2wd position (sometimes, other positions depending on where I slid in the terminal gear on the tc motor). I could also see the ADD switch back and forth (had this hanging off the differential as well).
After enough testing, suddenly the tc motor stopped moving at all. My lights are constantly flashing, unless I unplug the ECU. I tested voltages on the ECU and got wacky results. I replaced the ECU, which wasn't cheap, but it did not fix the issue. I have also bypassed the 4wd switch on the console, no different results.
As it 'appears':
- Good actuators
- New ECU
- Good 4wd console switch
- Good fuses (20 amp in console, 40 amp in engine bay)
- good switches on tc motor (those position sensors for the rod that sticks into the tc case)

I am sitting with lights flashing and now power to my tc motor.
I do not want to replace my whole wiring harness. I wonder if there are any other connectors I can test on the transmission, tc case, or front differential. Maybe even other fuses I am not aware of. I am at a loss and really need my 4WD, but don't have the need nor trust for another mechanic to throw my money at troubleshooting.

ANY ADVICE PLEASE
Cobra44, did you ever get yours working right? What were the issue verdicts?

 

Check your limit switch voltages as outlined in the thread below and post your results.

https://www.tacomaworld.com/threads/4wd-system-operation-help-thread.742420/

 

I'd rather change a CV on the trail than do this again. I was not getting any continuity in those first 2 pins. One of the springs was mangled and not pushing the contacts up to the motor.



it took me forever but I was able to reset the springs and contacts and I'm now good to go. One of my springs is definitely mangled but I hope it will do for a bit.


I couldn't keep the contacts 'down' in the springs so I put some tap across the wires holding one down ... then the other. then slide the motor in. Patience. Frustration. Patience. Trial and error. Not sure if anyone else knows any tricks to keeping those contacts in place while trying to put the motor in?

I opened the front diff ADD to see and water poured out of it haha. I didn't take pics. The motor looks a bit corroded but I cleaned it up and all is well for now.

The good news is I now how to easily switch to 4wd manually if necessary and /or fix this. And if this becomes an issue I'll definitely go the manual fj case route. If you get into this I'd bench test everything before and while re-assembling.

Great thread -- thanks!!!