4lo not going into gear

Hi All-
Put my truck (4wd T/X auto) into 4lo to get up a driveway last night (steep + icy). About midway up I could feel a little tire slippage, felt the traction control grab a brake, and then it felt like the truck started sliding. It was late, so I parked it and walked in.

Went back this morning and was able to get the truck to switch to 4hi and drive it up to the house. Issue is that when I switch to 4lo (dead stop, put in neutral, wait for 4lo light to go solid) and then shift into drive or reverse, it doesn't move. Engine revs and nothing happens. When I switch back to 4hi, there's a slight grinding noise and then I'm able to move again.

Anyone seen this before? Hoping it's one of those finicky Tacoma things, and not a busted transfer case.

Also- any thoughts on driving it? I'm a good ways away from home and don't want to wreck my drivetrain if there's something broken that's going to bounce around the transfer case the whole time I'm running down the highway.

 

Getting into, and out of low range can be difficult with any 4X4 vehicle. I find it works best to shift to 4hi while driving and already be in 4X4 before trying to shift to low range. Technically you should be able to go from 2wd to 4lo in one step. But I just have fewer problems breaking it into 2 steps.

And it will make the shift to low range a lot better if you are moving SLOWLY rather than at a dead stop. I think the owners manual says under 3 mph. If you're at a dead stop you have about 50/50 odds of the gears in the transfer case being aligned properly to engage. If moving slowly it will engage when everything lines up.

This is why it is best to engage 4X4 and/or low range BEFORE you get stuck. If your front wheels can't turn slightly neither may engage. Getting OUT of low range can be even harder. If driven for any distance, particularly if in areas where traction is decent the gears get bound up and don't want to disengage. Driving in reverse for a few feet will often help. This can be an issue with ALL 4X4's BTW, not just Tacoma.

Using low range wasn't going to help get you up the driveway anyway. In fact it was the opposite approach you should have taken. Low range puts too much torque on the ground and increases the odds of wheel slippage.

I'd get it on a snow covered road, gravel road or some surface where you won't break anything in 4X4 and drive a few miles in 4X4 hi. Then try to go back to 4lo as I described above. I don't think you've broken anything.

 

Yeah like stated you must be 100% all the way into 4hi before thinking about switching to 4lo. That is zero dash lights flashing etc with the selector in 4hi. Then and only then can you be under 3mph with the auto trans in neutral to shift to 4lo and again the only time it will be fully in 4lo is if there are no flashing lights, sometimes if you are in a situation where you cant move you can get away with selecting 4hi and giving it a little gas to spin a tire to line everything up, then go for 4lo (remember to put in neutral) and if its flashing while standing still in neutral put it in drive to spin things ever so slightly for it to click fully into 4lo without moving.

 

Think maybe I wasn’t explaining the situation that clearly.

I can drive in 4hi, but when I try to switch to 4lo the sensors seem to think it’s engaged (4lo light blinks then goes solid) but the truck is essentially in neutral. It will roll with whatever slope it’s on, but there’s no power to the wheels. I tried engaging 4lo in neutral at low speed and got the same result.

When I switch back from 4lo to 4hi, there’s a little grind and then it locks in. Worried that something has sheared off and I’m basically spinning gears around the drive shaft when it’s in 4lo.

 

Ahhhh ok. Sounds like the actuator on the tcase is sticky (there is a spot between 4hi and 4lo that will give a false neutral on our tcases). Id pull the actuator (with it in 2hi) and manually move the rod back n forth fully a few times, returning it to its 2hi position. Then do the same for the actuator, pull it apart and clean it.

 

This is an odd case for sure.
That rod that slide in and out, physically pushes on the 4Lo position switch. The rod almost had to be going all the way out. Other wise the 4Lo light would not stay on. Strange case case for sure.
Something is “physical” off here. I don’t think this one is going to be electronic.

 

Took it into the shop this morning. They're telling me there's a crack transfer case actuator housing, so the actuator is getting wet, acting up, and will fail entirely at some point. I don't have a garage to work in so I don't really have the option of taking care of it myself, I don't think.

 

Is there? Like @TnShooter said above I thought the rod had to be in the 4Lo position before the indicator would be made. Slightly different design than the 3rd gens

 

Im pretty sure there is cus there have been a few who have rebuilt the actuator and not indexed it proper and end up with a false neutral. But i could be wrong.

 

The 4WD ECU controls the indicator light.
The 4Lo light should not come on if all the correct parameters are met.

This is a strange case, without knowing the “coding” of the ECU, we can’t be sure what the actual parameters are. I would want the Transfer case Actuator and the L4 indicator switch to be in agreeance before the 4Lo light would be turned on.

This is one that @Dm93 could probably figure out.

According to OP, his 4Lo light comes on.
But he is NOT in 4Lo. To me, this says that signal for the light is based on the Actuator signal, and not the L4 indicator switch.

 

For clarification, this is the position indicator switch.

 

It also got significantly slower in terms of locking into 4hi (i.e. switch to 4hi, definitely have power to the front end, but light blinks for 100 yds before going solid) which does seem to point to the actuator being an issue.

I've looked up enough stuff on these forums to know that this answer probably exists somewhere, but I can't seem to find it: Is there a thread that lists solid/recommended shops? I like my local guy in Brooklyn, but I'd love to find someone who's a Tacoma expert to deal with this kind of issue.

 

IMO all 2nd gen "4WD help" threads / requests should at least mention the existence of the comprehensive 2nd gen 4WD system discussion, diagramming, operation guide, & pinout thread here:

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

 

My tcase got stuck in Neutral in between 4hi and 4low. Engine would rev, no drive shafts would turn. I manually moved the shift rod on tcase to get it out of 4L and reindexed the actuator. After that drove it for a bit shifting from 4H to 2H to 4H....no problems. When I try 4L, it doesn't like to go, but if it makes it from H and starts to go towards L, it gets jammed in N... which requires manual actuator movement /resetting.

I am convinced I bent something inside the tcase that is preventing it from going into 4L. I have been driving in 4H or 2H for a while, no issues. When it gets warmer, I'm pulling the tcase and opening it up to see what's going on.

 

I could test and see but I'm almost certain the 4wd ECU will not turn the 4LO light solid until it sees the L4 switch close.
Theoretically there should be now way for the switch to be closed unless the transfer case is fully in 4low but it seems this is not always the case. Now whether this is due to wear or a mechanical problem in the transfer case or an issue with the Transfer Case Actuator is unknown but I would tend to lean toward a mechanical problem or wear on a shift fork in the transfer case based on how the system is designed.
I'm not exactly sure how the shift forks are actuated in the transfer case itself having never been in one, I watched the video below but it's not clear exactly how the high/low shift fork operates.

https://www.youtube.com/watch?v=ak2jDzVQIdU

 

This video, non-English, shows how the tcase shifts from 2H to 4H. I don't think it shows how it shifts from 4H to 4L, but you get the idea.

When the actuator is all the way into the case that is 2H. Pulling actuator out 1 position gets you 4H. One more spot out gets you 4L. For 4L, the fork pulls the planetary gear closer to the rear of the truck. The video shows the fork pulling the chain gear closer to the rear to engage 4H. Must be the same concept for 4L, but with the planetary gear.

https://youtu.be/6ne-Xq2bNA8

 

Interesting, I wish I knew what he was saying. I wonder if the wear shown in the video is a possible cause of this problem.



I did find this, pretty good explanation of how it moves.

 

This video is for the mid-2010's-era Tundra T-case, but this one is probably very similar in design & operation to a Tacoma's, only with bigger parts inside for more load capacity.
Toward the last 1/4th of the video he uses 12V power to force the actuator to actually move the shift fork in & out.

https://www.youtube.com/watch?v=4UoBCIjWIoU

 

I watched it, while the shift forks move in a similar fashion the way they are interconnected is quite different from the Tacoma as both shift rods are part of the actuator on the Tundra transfer case.

 

Whoops, my bad. LMK if you think I should just delete the post entirely.