Stuck in 4Hi need to get back to 2WD

'15 Tacoma TRD Off Road

Did a front/rear diff & transfer case fluid drain and refill. Used Valvoline Synthetic SAE

$30 75W-90 Synthetic Gear Lube - 1 Quart (Pack of 2)

75W-90 Gear Oil, checked the oil amounts, and made sure that everything was done correctly.

Went on a test drive per usual and put the truck in 4Hi. The truck now will not go back into 2WD. The green light on the dash just flashes when I switch it from 4Hi to 2wd. I can hear the actuators in the dash and under the truck clicking as usual but the light on the dash continues to blink when the knob is set to 2WD. Goes back to solid when I put it into 4Hi.

The question is, did I use the wrong fluid? or is this 4Hi -> 2WD issue just a coincidence? Can the fluid you put into the transfer case and front diff mess with the truck's ability to switch between 4Hi and back into 2WD? No issue going from 4Hi to 4Lo and back to 4Hi. The only issue is going back to 2WD from 4Hi.

I'm at a loss.

PS - Spent about three hours scouring the site for an answer to this and it seems everyone's issue/posts are about getting INTO 4WD and not out of 4WD

 

The fluid will not interfere in the actions of any mechanical on your truck
I am sure there are some taco gurus in this form that could possibly give you a more in-depth answer on why that is happening

 

Almost certainly has nothing to do with changing the fluid.
You didn't accidentally knock any connectors off any of the 4wd actuators while you were under there did you?
Were the vent hoses still attached to the actuators?

If that's all good then 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/

 

@Geeves77 Yea I didn't think it would but seems like an odd coincidence to say the least.

 

The Transfer case vent hose was cracked and I am sure not on correctly, I trimmed it back and replaced it snuggly on the vent of the actuator. That did not fix the issue. Is there something that needs resetting after a vent hose comes off? I trimmed about 10mm off the end and it seemed to have enough extra length to just be reinstalled.

 

If the vent hose was off the actuator may be full of dirt an moisture which can cause issues.
You can take the actuator apart and clean it up if that's the case just make sure the drive gear stays in place or you will have to re-time it which can be tricky.

 

Yea, I don't think it's gotten water in it as I have not run it through any high water or excessive rain or anything. Also, am I understanding that the 2WD actuation is handled by the front diff ADD, and the 4Hi -> 4Lo is handled by the transfer case actuator?

 

Before the fluid change when did you actuate the 4WD system last?

 

I mean you basically have 2 options, check your limit switch voltages so we can find what part we need to check or start taking stuff apart looking for the problem.

They work together, the ADD locks the front axle in and the transfer case locks the front driveshaft in.

The transfer case has 2 shift forks, one locks and unlocks the front driveshaft and the other selects high and low range. The Transfer Case Actuator operates them sequentially.

 

A week or two before the fluid change

 

I'm thinking that I am going to order a new front diff ADD actuator and a new transfer case actuator and replace the old ones. Hopefully, that fixes the issue. I am less likely to spend hours troubleshooting the electrical when I can hear the actuators trying to move. The truck has 100k miles on it so replacing those parts gives me a piece of mind anyway.

 

You able to get the truck up in the air on jackstands so the wheels can spin freely? Id do it with all the wheels off

 

If anything you can remove the actuator and pull the FDSF (front drive shift fork) manually

 

There was a video on YouTube of someone doing it as thier truck was stuck in 4wd. Toyota should have given us a damn stick lever for the 4wd

 

Up to you but I would reccomend doing the voltage checks, all it takes is one of the limit switches being out of range to keep the system from operating properly and the majority of the time they can be fixed no parts required. The OE actuators don't fail very often but the aftermarket ones are hit or miss.

 

Yea I have jack stands

 

That sounds like a reasonable thing to do, where and what are these limit switches I need to check, and is there a voltage guide I can follow?

 

It's all in the thread I posted above.
https://www.tacomaworld.com/threads/4wd-system-operation-help-thread.742420/

 

I have a stick on my old Silverado, I wish Tacomas had them too. I had a previous Silverado with 2WD/4WD push buttons on the dash, and it would get stuck in 4WD. I'm fortunate so far my 2007 Tacoma has been fine, had to put it in 4WD last month when backing uphill on dirt to get firewood.

I hope the OP will find it was something minor. I thought I've seen information involving going in reverse when stuck in 4WD, but maybe that's been covered here in the links or the OP tried that.

 

Yea, I've tried all the "quick hacks/fixes" but nothing works so I am thinking it's something more involved.