06 Will not disengage 4wd HI, ECU clicking

I've seen lots of posts about 4wd not disengaging but, this usually includes not able to shift to 4wd LO. I can shift into 4wd HI or LO but I cannot switch out of 4wd LO. When I attempt shifting out of 4wd HI, I hear a series of clicking come from the ECU behind the passenger dash. The clicking has been normal in the past but this sounds as though it's not being successful. Could the ECU be going bad? Shifting out of 4wd HI has always been a bit lengthy but, if it's successful, it can take up to 10 miles before successfully disengaging.

 

Check your limit switch voltages as outlined in the thread below and post your results so we can see what we need to look at.

4wd System Operation & Help Thread | Tacoma World

 

10-4. I gotta grab some needle probes first. You perform the check while cables are plugged into the ECU and truck is on?

 

Yes key on engine off, make sure to check it when the problem occurs.

 

Front actuator, may have water or corrosion in it.

 

I was thinking the same. Don't you have to take actuator off to confirm?

 

You would but this typically would only happen if the vent line becomes disconnected or has a hole in it, same thing with the Transfer Case Actuator.

I'd rather do the limit switch voltage checks and know what we're after but it certainly wouldn't hurt to crawl under the truck and check the vent hoses on the actuators. If one is broken or disconnected odds are the actuator has water and dirt in it.

 

Here's the results of the terminal test trying to go back into 2wd:

 

Based upon these readings, what's my best plan of action?

 

Is TL1 at 12v

So it looks like the actuator moved but the transfer case is not wanting to come out of 4wd for some reason, are you sure the driveline isn't in a bind?

 

As far as "a bind", do you mean was pressure put on the front end like going uphill in 4wd? If so, no. The only thing I've done was change out the diff fluid a while back. I was just testing the 4wd on level ground 'cause it had begun taking forever to come out of 4wd HI.

 

When I say bind I don't nesseaarily mean like your going uphill, just turning in 4wd will put it in a bind. That's why it's not reccomended to use 4wd on high traction surfaces.
Usually you can back up a few feet to relieve any binding on the driveline or jack up the front wheels would do it too.

The only other 3 things I can think of it could be is the 4wd switch on the back of the actuator getting stuck, a problem in the transfer case itself that’s causing it to get hung. or a broken/weak spring in the actuator (which I have never seen).

 

Based upon your knowledge, is it a good idea to take down the actuator and check it?

 

Unless the 4WD detection switch is bad. But that’s unlikely. As to have it go bad, it would almost need to be “stuck”.

I’m intrigued as to how the TL switches are correct yet the 4WD switch detent is “stuck”. I mean the shift rod would have to move, or the gears in the actuator would have to slip.

 

It's no doubt still in 4wd. Just looking for some guidance here before I go to the auto parts store and pickup some diff fluid.

 

It isn’t going to come out of 4wd until the the detection switch on the transfer case is in the correct position. Diff fluid won’t help. Pulling the transfer case actuator and pressing the rod all the way in will get you in 2WD. So long as the detent switch is working. But won’t fix the issue.

 

If I take down the actuator it'll break the seal and drain some, if not all, of the diff fluid. Am I correct?
https://www.youtube.com/watch?v=ZJESG91GbCQ

 

Not if you just pull the motor.
You can not pull the whole actuator anyways.
The shift rod can only be removed form inside the transfer case. AKA dropping the transfer case. And you don’t want if need to do that. All the detection switches can be reached and serviced from outside the case.

 

BTW, we are not talking about the actuator on the front axle. It’s the one on the transfer case that isn’t reporting right.

 

This one.