Sticky 4-low

My new-to-me tacoma is sticking in 4-low.

When I bought it, it shifted in and out just fine on the test drive-
in the woods I couldn't get it into 4L and made do with 4WD.
I have NO idea if the guy who owned this truck before me had ever used 4wd or not, and he put ~120k on it.

it beeps and flashes and generally annoys me- but if I turn the truck off and let it cool down for a few minutes, when I start it I hear it ca-chunk back into 2WD.
I've done this twice, but I'm afraid to try it more because if I get stuck in Low I can't really go anywhere

I'm thinking this is likely a fairly common problem on the 2013 tacoma- so before I write two pages on what I've noticed I figured I'd throw it out here and see if there's a well known cause.

My first thoughts are a failing servo of some sort, or maybe something just needs to be taken apart and lubricated etc... I won't have time to look at it for another week or so, any input in the mean time could save me a ton of time.
cheers!

 

Sounds like you've owned Tacoma's before, but just in case - 4Lo you need to be under the computers speeds limit to make the Hi/Lo shift (into or out of 4Lo). But it shifts much easier if the truck is rolling fwd or backwards just a bit, not at a total standstill.

If that's not your issue, I would look under the truck at the actuator on the transfer case. Should see a small rubber vent hose coming off the plastic case. If thats missing or disconnected there's probably water and other crap inside the actuator. Which would be your issue.

If that's the case you might be able to take it apart, clean it and dry it, then grease it. But if the corrosion is too bad or if it got the motor you might need a new one.

 

If it's beeping it's not seeing the correct conditions to shift into or out of 4lo:

Transmission in neutral (AT) or clutch fully depressed (MT) and vehicle speed under 3 mph.

It helps to be rolling slightly with the wheels straight ahead when you attempt a shift.

Also check the vent hoses on the actuators and make sure they are connected and in good condition.

See the thread below for more information about the 4wd system.
https://www.tacomaworld.com/threads/4wd-system-operation-help-thread.742420/

 

If 4X4 isn't used regularly it can be hard to engage/disengage. Some tips:

It is best to shift into 4hi on the move. Simply move the dial to 4X4 while you're driving on a surface with somewhat loose traction. A loose dirt or gravel road is best, but grass is OK. It may take a few seconds to engage. The gears in the transfer case need to be aligned in the right position in order to engage. If you try to do this from a dead stop you have roughly 50/50 odds the gears are aligned right. If not, it won't engage until you start driving and the wheels have turned a partial rotation. To get out, do the same. Once again it may take a few seconds. If the truck hasn't been used in 4X4 regularly it may take more than a few seconds, and may not engage/disengage at all until repaired.

Getting into and out of low range can be difficult with any 4X4. To engage I find it best to get into 4hi as described above. Once you're engaged come to a near stop. Place the transmission in neutral. Or with a manual fully depress the clutch. Once again it is best if you're moving SLOWLY in this case. No more than 1-3 mph. The gears need to be aligned before they will engage. And if at a dead stop may not engage unless the truck is moving slowly. Low range won't engage above about 3 mph. I may come to a dead stop, but on a slight incline. As I make the shift I'll release the brake and allow the truck to roll slightly to engage low range.

If you've been in low range for a while, especially if you've been driving in conditions where traction is not really slippery the gears get bound up tight and they don't want to release. If this happens you need to leave the selector in 4 low and back up 10-15', then pull forward 10-15' and try again. Driving in reverse helps relieve the binding. It isn't unusual to have to do this little dance 3-4 times before you get things to let go.

Once again, don't try to go directly from 4lo to 2hi. I find it works best to go from 4lo to 4hi. Then after you're in 4hi you can then shift to 2hi as you're driving away.

Technically you should be able to do this in 1 step. And often you can. I just have less problems doing it in 2 separate steps.

 

I'll crawl under there this weekend and see about the vent hose... I'm due for an oil change anyway

I had to let the truck sit and cool off for it to shift out- no combination of moving around or shifting or fiddling with switches or holding the clutch in etc etc made any difference. Cursing at it didn't help either... stupid computers.
My money is on whatever electronic device in charge of moving from 4l to 4h is failing, I'm assuming it's going to be the only plastic thing bolted to the transfer case.

I have had a tacoma before- but this is my first 4wd one, and my second ever 4wd vehicle- first 4wd was a chevy, and the lever physically moved the gears so it never had a problem.
Electronics always fail...

 

All it is in there is 3 limit switch contacts, some gears, and a motor, does it shift fine from 2h to 4h and from 4h to 2h?
Take a look here, I have pictures, diagrams, system info, and more.
4wd System Operation & Help Thread | Tacoma World

 

so far it's shifted from 2H to 4H just fine, and even into 4L just fine- but going the other way can take 20 minutes or more to get out of 4L. I haven't tried much going from 4H to 2H.

The best luck I've had is just shutting off the truck and letting it cool off for 15 minutes, then the instant I start the truck again I hear a CLUNK and it's back in 2H

I was just outside taking another photo for another project and remembered this, so I popped my head under and took a quick picture-

Sure enough, I only saw one plastic thing down there and...
This appears to be the actuator covered in those other links, with a lovely big crack in it. Stupid plastic parts.
I can't tell if this crack is just on the area the bolt is in or bad enough to allow water into the device, so I guess once I wrap up my current driveway project I'll be taking this off to see inside.

 

Take the cover off and inspect, clean as necessary. You can probably get away with sealing the crack back up with some silicone.

 

I hate the factory actuated transfer case. Had many issues of it freezing while snow wheeling and or camping in the snow. it would lock into 4lo and id have to drive home like that or hope that by the time the trail ended it was warm enough to switch. The final straw was camping for a week and while traveling the coast we found a cool spot that let us camp on the side of a river.. I stacked rocks and went 4lo to get up on them. left the truck like that all night. Next morning the truck wouldnt leave 4lo.. we drove almost 25m trying to get it unlocked. after about an hour of backing up, going forward, lock to lock turning , shutting the truck off, having to disconnect my trailer... I was over it! Running a 2016 4runner manual Tcase with twin sticks.. Its so much better!

 

I still haven't had a chance to pull this apart (just moved into a new house, still trying to get the lawnmower/garden tractor back together... and soon I'll be getting ready for the snowblower!)

I did however have two days last weekend where I had to head up to the hill, and switching to 4H from 2H and back worked just fine both times!

Not sure what the difference is with 4l- might it be related to the harder-to-reach box up front?

 

Nope, the ADD (on the front diff) only actuates during the 2Hi > 4Hi or 4Hi > 2Hi shifts. The ADD doesn't do anything shifting into or out of 4Lo, thats all in the T-case.

 

That makes sense, now that I think about it. Excellent news!

I've been headed up to my hill (half mile offroad in and out) about once a week for various reasons, and switching into and out of 4H at the gate without issue.
I've not been brave enough to try 4L again just yet. Might be going into the shop for engine problems, I don't have time for the DD to be breaking down