4wd Actuator Teardown/Repair (Seized 4lo)

Similar to my engine swap write-up, I haven't seen a lot of documentation on this project as a whole - just the first half about working on the 4hi/CDL, or mentions of doing this, but no real write-ups. Each work "segment" will be a separate post to make things more convenient (and shorten the post lengths). I will also repost all timing reference photos and tips I have at the end for easy access. My hope is to help others get theirs fixed by removing some of the fears with all the unknowns. I apologize in advance because this write up is probably obnoxiously long. [MENTION=429038]y=mx+b[/MENTION] maybe this can make the list under Eturtle's?

Story is: my 4hi/CDL intermittently worked, and my 4lo that was seized up beyond repair. So here's my documentation on how to remove the actuator, how to tear it down, and how to time it and reinstall it without cracking open the transfer case. Now obviously this isn't ideal, but when Toyota calls it "non-serviceable" and charges a grand for a new one, we gotta make due. I had already tried the jiggle it and beat it with a deadblow hammer trick (That's why my 4hi worked, cause it used to not). But if you're having issues like me, you may want to go ahead and do this to prevent it getting worse.

I was able to get it back on the truck, working good, and accurately timed as far as I can tell (at least close). I haven't had any errors while shifting (yet), and I can confirm all three actuator positions are engaging

Update: I've had a few issues with the actuator now that I've tested it more. 4lo is still good, but it seems to get confused and not want to shift into 4hi half the time. Or it tries to shift to 4hi, but locks up in an error state, so I have to take the drive gear out, manually shove it back to 2hi, and then put it back together. I think something else has gone wrong electrically (meaning not my timing from the teardown), so I'm going to go back and use the electrical diagrams to make sure everything is ok. I'll reupdate once I know more.

Reupdate: I got everything working perfectly. It was exactly what I suspected - Something electrical. It was the bad encoder wheel I talk about in this post: https://www.toyota-4runner.org/3841567-post12.html

Before we begin, please note, this is an overnight, two day job at minimum - so make sure you have the time to complete it (I was ambitious and ended up using my whole weekend plus a sick day). I would not drive my truck with the actuator off, so make sure you get everything you need beforehand, or have a second method of transportation. Also, I read this thread by [MENTION=88240]Eturtle53[/MENTION] to get familiar with the process - I recommend checking it out: DIY Transfer Case Actuator Repair. This is also a video that talks about it: https://www.youtube.com/watch?si=j4zVEmo8GH-xJqRS&v=aZNKwHdbXa8&feature=youtu.be
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Tools/Items used:

-Philips head screwdriver
-Metallic sharpie/paint pen
-Needle nose pliers
-Multimeter
-WD-40
-Evaporust
-Silicone Spray
-QD Contact cleaner
-Dielectric/Silicone grease (I've seen people recommend white lithium grease, but from my research, its petroleum base is harmful to plastic and rubber)
-Toothbrush
-Qtips
-Dewalt 20v battery (or bench power supply)
-Wire w/ male+female flat blade terminals on ends

Actuator Testing/Removal

Testing/Removal:

Step one: diagnose a seized motor is actually the issue. Using the very handy pdf reference charts and diagrams attached to this post, probe the 4wd computer (while it's plugged in and the truck is on). I used some small test wire (22g I think) to shove in the back of the pin and then put the multimeter on that.

Once I knew the only issue I was dealing with was a seized 4lo motor, I tried overvolting the motor to break it loose as mentioned by [MENTION=173290]feralcomprehension[/MENTION] in this thread: Fixed my T-case Actuator w/ electricity and logic. Except I didn't have access to a bench power supply, so I just used a wire with a flat blade connector shoved in the terminals of a 20v Dewalt battery :laugh: As mentioned by Feral, the motors are good up to 30v, so I knew the 20v battery was fine

The motor was way too seized for that to work, so disassembly was my next option. I jacked the truck up and got one front tire and one rear tire off the ground so I could have the truck in neutral and spin the driveshafts by hand to move the shift forks as needed. I unplugged the actuator, unscrewed the cover, and sprayed what I could see with contact cleaner. As recommended by Eturtle, I marked the large gear with metal tabs (in reference to the case) and the blue encoder wheel with my sharpie (Side note: the sharpie will wipe off, especially when you go to clean everything, so I think a paint marker would be better. If you use a sharpie like me, take some good reference photos - that's the only thing that saved me)

This is what mine looked like (rusty). You can see my silver sharpie marks



After marking, take out the two screws holding in the first layer with the blue encoder wheel. It just pulls out with a little wiggling. With that out, the drive gears for the 4hi/CDL shaft are exposed and will just slide off the shaft. The only important gear here that needs to be timed is the one with the metal tabs that actually drives the shift fork, so that is why we marked it. The other two gears just move the drive gear and spin the encoder. With these out of the way, the 4hi/CDL shift fork is now exposed. You can move it around if you want, you won't mess anything up. At this stage, you want to mark the tan encoder wheel that tracks the 4lo system.




This is where things get tricky. Because from this point on, the actuator needs to be removed from the transfer case. The *proper* way is to drop the whole transfer case, crack it open, and actually unbolt the shift forks. But I didn't want to do all that, so this'll work. Be careful during this part because there are rubber seals around the shift forks that you don't want to destroy. The best way I found, and what ended up working for me, was pulling the metal shaft closest to the inside (that the idler gear for the 4hi/CDL worm gear sits on). That shaft also holds the the 4lo worm gear idler, so pulling it out allows the idler to fall to the side so the drive gear can free spin as you pull the actuator off the shaft (otherwise the gears lock it on). To keep from damaging/scoring the shaft, I wrapped the teeth of my pliers in electrical tape, then used them to pull it out. With the gears freed up, take out the three bolts holding the actuator on, and pull it off. Mine was stuck and I had to work it back and forth. Same as the 4hi/CDL shaft, its ok to move the now exposed 4lo shaft

Actuator Teardown/Repair

Teardown/Repair:

With the actuator off the truck, take it inside so you can work on it in the A/C with snacks and drinks nearby. Remove the 5 screws holding the second layer in, and same as the first layer, pull it out while wiggling it, Because it slides on the middle shaft, you may need to use your pliers to help persuade it out. That will expose the 4lo actuator gear set. The last thing to do is to remove the two screws holding in the third layer with the 4lo motor and pull it out. Theoretically, you could just buy new motors to replace the old ones at this point, but I went with fixing the stock ones.




With the actuator dissembled, clean everything off with contact cleaner. Using the cleaner and a toothbrush, clean all the old grease off. Separate all the gears (be careful with the spring gears, they have a small metal washer/disk between the spring gear and the plastic gear that you don't want to lose). Soak every metal part in Evaporust (I don't have a pic, but I also soaked a paper towel in the Evaporust and wrapped it around the shift forks on the truck to clean those up too). I did a lot of reading to find something safe to use on the actuator parts - this stuff works incredibly well and is safe on plastic and rubber. Mine was pretty bad, so I let mine soak over night before I scrubbed and rinsed them off. After rinsing, I put the bad pieces back in to soak for another few hours. I unscrewed the 4lo motor and took the worm gear out so I could use a pair of pliers to work the motor loose. It was pretty stuck, but I was able to break it free. Then I sprayed WD-40 in it and used the Dewalt battery to confirm it was working. I sprayed it out with contact cleaner and put it back in the Evaporust, then I spun it with my finger and moved it around to work out all the air and make sure it filled the inside.



After the last few parts soaked in the evaporust a few more hours, I took them out and rinsed them. After rinsing, I set everything out in the sun so it could dry. Once that was done, I sprayed WD-40 and silicone spray inside both the motors and used my Dewalt battery setup to clean and lube the inside of the motors.

Actuator Reassembly + Testing

Reassembly:
With everything de-rusted and working, it's time to put it all back together. This part sucks to be honest. The grease is sticky, it gets on everything, everything is slick and hard to hold, and timing everything is tedious. But it's worth it, and it's 100% do-able, so stick in there.

I didn't have any rust block, so I sprayed all the metal parts with a coating of WD-40 that I let dry to help prevent rust in the future. All gear teeth, moving parts, and contact points got greased. I also sprayed the silicone on the shafts to give it a lubricating film, and used a qtip to get a little grease in the holes the shafts ride in. Start by screwing the 4lo motor back in. Using the dielectric grease, apply a generous glob to the brass worm gear and the slot the 4lo shift fork slides in. You can even take the worm gear plate off and shove some behind it too. Next goes the shafts, idler gear, and the half-moon gear (Grease the bottom face as well, because the bottom side slides over the shift fork). Now you gotta time the drive gear. I used this video as a reference. Look around the 11 minute mark: https://www.youtube.com/watch?si=GqMBeP26i7S5Z7qK&v=aZNKwHdbXa8&feature=youtu.be

Except what he says is backwards. The gear fully forward is 4lo, so time it as he says (first pic), then spin it backwards until it looks like two teeth would contacting the shift fork (the second picture). I know this isn't exact, but the gear doesn't spin completely back (the teeth lose contact and it comes loose), so this is the best way I found that works.




Once it's timed, slide the larger idler gear in place. With that in, the drive gear can't free spin, so the timing will hold. Now make sure your tan encoder wheel is properly aligned and install the second layer. Tighten the 5 screws that hold it and generously grease the slot the shift fork rides in, and don't forget the brass worm gear too.

Edit: this would be a good place to point out that the teeth on the drive gear are large enough, that you should be able to get it pretty close since the next teeth alignment will be noticeably off



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Testing:
I recommend reassembling the whole thing at this point and plugging it in to make sure it functions as it should and the timing is right. Because the timing is independent of the shift forks, you can know if you got it right or not before installing it.

Slide the idler gear into place and then time the drive gear using your mark or reference photos. Lock it in with the larger idler gear. Now align the blue encoder wheel and install the first layer. Screw it down and put the actuator cover on. Just use the three screws that don't go in the metal shield to save time. Plug it into the truck and run the actuator through all three positions. You obviously won't hear the gears engage, but you should hear the motors move then the light on the dash come on. If anything stays blinking or you get the wrong dash light (i.e CDL light when only doing 4hi), then your timing is off and you need to take it apart and retry. If the computer goes into an error state (all three lights rapidly flash), turn the key off to reset it and try again. If it keeps doing that and it didn't just get confused the first time, then that also means the timing is off.

This is where I discovered another issue I had. Because a seized DC motor is basically a direct short that will pull as much power as it can, I developed this issue from all the times I "checked it was still stuck" (I know for a fact it wasn't from me overvolting the motor with the battery because my actuator had stopped giving the seized motor error beep a week or two prior to taking it apart, meaning the motor lost power before I started working on it)



That's melted copper tracing in the 4wd computer. IDK why it didn't pop the fuse before it did that. But that's the tracing that provides power to the pins for the 4lo motor. So when I plugged mine in and moved the switch, it wasn't moving - even though I had confirmed it worked with my dewalt battery. So I soldered in a jumper wire and covered it in hot glue



Not the best work, but I'll take what I can get with a borrowed Walmart soldering iron. Now that I fixed that, my actuator worked! It was such a relief to 1) finally have a fully functioning actuator again, and 2) know I was at least close with the timing since I basically guessed off of visual references

Actuator Reinstall + Functionality Confirmation

Reinstall:
Time to try and get it back on the truck. Take the 4hi/CDL gears back out (you should already know how to align the timing, so it's ok). With the bottom half of the actuator out, now you only have to worry about getting 4lo on, which is a lot easier than trying to do both. The way I did it, was I pushed the actuator on as far as I could (be careful putting it on. There's rubber seals that go around the shift forks that you don't want to tear up - I'm pretty sure I nicked mine with the teeth on the fork, so we'll see if I get any leaks). Since the gears are locked and won't free spin, I needed the motor to help me out. Thankfully, the shaft is only keyed for its designed range of motion (as far as I could tell), meaning you should be able to use the motor to pull it onto the shaft without messing up the timing - which seemed to work for me

So, as I said, I pushed the actuator as far as I could by hand (which should also push the 4lo shift fork completely in, engaging the hi range), then using my dewalt battery setup again, I slid the female blade terminals onto the power prongs for the 4lo motor (t3-7 and t3-8) and gave it a few quick bursts of power while pushing on the actuator so the teeth would grab and pull itself into the shaft. I did that a few times until was far enough on that the actuator was fully seated. Then I put the three bolts in and tightened them up. No need to worry about the shaft being in between positions - As long as you had it correctly timed to begin with, the computer should reposition to the proper state when you turn it on and it does the self-check.

With that hopefully on correctly, you can put the 4hi/CDL section back. Make sure the shift fork is pushed all the way in (you may need to wiggle the driveshafts if it doesn't want to go). Then you can reinstall the gears and time them like you did earlier. Put the cover back on too.


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Confirm Functionality:
With it back on the truck, you'll want to make sure it's still working. Plug the actuator in, turn the truck on, and cycle it through the three positions. Again, if the computer locks up in the error state the first time or two, just power cycle it and see if it starts working. Same as earlier, if it doesn't engage, the wrong lights come on, or it keeps locking up in an error state, then something is wrong - most likely the timing. You'll need to take it off and open it up and retime it, then just keep repeating the install and test until it cycles on the truck without error.

Once it's cycling on the truck without problems, it's time to drive it and confirm the shift forks are engaging properly. Drop the truck off the jack stands and take it for a drive. Obviously 2wd should be fine, but it's always good to confirm and listen for any odd noises. Then cycle the actuator is make sure its doing what it should. Here's some easy ways to know everything is engaging: 4wd will "pull" the steering wheel to center when accelerating out of turns, a locked center diff will bind while turning full lock at idle, and 4lo is obvious because the rpm range changes.

Actuator Timing References

These are my timing references. I didn't get it perfect, but I got it close enough to work. I recommend taking your own, these are more for that "oh crap my mark is gone" moment

Stock 2hi timing for 4hi/CDL gears:


Stock 4hi timing for 4lo gears (tan encoder wheel):


Stock 4hi timing for 4lo gears (around 11 minutes, the timing he talks about is 4lo, so time it and then spin it into 4hi):
https://youtu.be/aZNKwHdbXa8?si=j4zVEmo8GH-xJqRS

Awesome write up. I haven't (and hopefully never) had to do this, but I have looked into it just in case. There was some info out there, scattered amongst posts, but this is the comprehensive write up that was needed. Thanks!

Nice!

Excellent write up, good job on all the details. People probably wonder why you always have a smile on your face when you are in the T4R...cuz you fixed it yourself :rockon:

Awesome pics and service manual pdf attachments. Thanks for writing this up! I have this added to the mega list now!

Excellent work! Glad to see the mechanical and trouble shooting skills in a young person!
I was too busy being a dumb ass at your age.

4RunnerAquasport said:

Excellent work! Glad to see the mechanical and trouble shooting skills in a young person!
I was too busy being a dumb ass at your age.

Click to expand...

Oh trust me, its a good mix of both :laugh:

P_nlsn said:

Update: I've had a few issues with the actuator now that I've tested it more. 4lo is still good, but it seems to get confused and not want to shift into 4hi half the time. Or it tries to shift to 4hi, but locks up in an error state, so I have to take the drive gear out, manually shove it back to 2hi, and then put it back together. I think something else has gone wrong electrically (meaning not my timing from the teardown), so I'm going to go back and use the electrical diagrams to make sure everything is ok. I'll reupdate once I know more.

Update: I got everything working perfectly. It was exactly what I suspected - Something electrical. It was the bad encoder wheel I talk about in this post

Click to expand...

Well, I found the problem. This guy right here:


I was using the electrical diagrams and service manuals to try and figure out what was going on. Found a couple sensors that weren't in the right position, so I opened it up and took the the blue 4hi encoder wheel out. I started probing it with a multimeter while I spun it and realized one the posts wasn't ever being engaged. I popped the gear off and found that. The second from the right was so corroded it wasn't contacting even when pushed down. I cleaned it up with another evaporust bath and some scraping. Confirmed it was fixed with the multimeter, and put it back together. Works good as new :thumb3:

I'm super relieved I was able to get it fixed, and that it wasn't something I messed up :laugh:

Morning!

I recently purchased my T4R. There have been a host of repairs to the vehicle since I bought it; weld-work, cv axles, brake assembly, interior strip out, etc.

While driving into work this morning, my CEL kicked on and started flashing. I pulled off, turned the vehicle off as it definitely felt like a misfire issue. I kicked it back on to get to work because frankly there just aren't that many options down here.

While driving the 4LO light came on and stayed on until I got to work. No more flashing CEL though.

My ECU is not reading. The OBD-II scanner I have works on other vehicles with testing, so I've determined it's most likely my ECU connection.

Any insight as to whether I may be having a similar issue to what you were dealing with?

Appreciate you reading through this and giving your insight. All the best!

CayRunner said:

Morning!

I recently purchased my T4R. There have been a host of repairs to the vehicle since I bought it; weld-work, cv axles, brake assembly, interior strip out, etc.

While driving into work this morning, my CEL kicked on and started flashing. I pulled off, turned the vehicle off as it definitely felt like a misfire issue. I kicked it back on to get to work because frankly there just aren't that many options down here.

While driving the 4LO light came on and stayed on until I got to work. No more flashing CEL though.

My ECU is not reading. The OBD-II scanner I have works on other vehicles with testing, so I've determined it's most likely my ECU connection.

Any insight as to whether I may be having a similar issue to what you were dealing with?

Appreciate you reading through this and giving your insight. All the best!

Click to expand...

As far as I know, the transfer case should have zero effect on the CEL, so it sounds like you're experiencing two separate issues; whatever is causing the CEL/misfire and then whatever made the 4LO light come on when it wasn't actually engaged.

If you're getting absolutely nothing on the OBD then it does sound like it could be an ECU issue, but I would start with checking the fuse. Wish I could be more help, good luck!