2002 automatic 3.4 TRD - 4wd not engaging

Hello all,
I been reading threads about this issue for hours and I feel like my head is spinning. I’m hoping I can get some more concentrated information from you fine folks here.

First off, I use 4wd often and presently nearly everyday now that it’s winter in Tahoe. Today I was in 2wd and my wheels were slipping so I pushed the 2-4 selector button to engage 4wd. In the past, I don’t believe I’ve ever switched over while the wheels were slipping, but there’s a first time for everything... There was a loud clunk, a bit louder than the usual clunk, but 4wd never engaged and the 4wd indicator light didn’t come on. I pressed it again and nothing. I pulled over, restarted the truck, pressed the button and thankfully 4wd did engage. Thinking it was a fluke, minutes later I pressed the button to disengage 4wd, to which it did, and then tried engaging into 4wd again and nothing. No indicator light, no sounds, no 4wd.

I couldn’t even get all the way up my driveway and into my parking spot which was quite embarrassing haha.

Fast forward after a couple of hours of research and I’m out there tapping on the transfer case actuator. Upon startup I notice the indicator light is now on, however it isn’t in 4wd. Wheels are spinning, definitely still in 2wd. Pushing the button does nothing, light remains on throughout. An hour later I decide to try again. After startup I notice the indicator light is off now, I press the button and out of dumb luck it pops into 4wd and the indicator light comes on. I’m able to effortlessly pull the truck into my parking spot; thankfully out of the way and into in a safe spot in case the issue becomes reoccurring. Well it does. I disengage 4wd, to which it does, but the indicator light stays on. Pressing button doesn’t do anything. I restart, and while the light is off this time, the button has no effect and it’s stuck in 2wd again.

Few things:

-When I press the 2-4 selector switch I hear no sounds at all (I would usually hear the electrical motor whirring in the transfer case actuator)

-I pulled off the plastic portion of the transfer case actuator and it look like this (pictures below). I’m not sure if this looks bad or decent, but regardless I cleaned and regreased it before putting it back on the truck.

-Even with PB Blaster I unfortunately wasn’t able to break the Phillips screws loose on the motor section of the actuator in the picture, so I’m not sure how it looks in there.

-the tubes that run to both actuators appear intact and connected (still not sure if those are breather tubes or vacuum tubes)

-The electrical connectors appear clean and are connected. Are these what people refer to as “switches?” How many do I have? I see two connections on the transfer case actuator, and although I can’t get a good look at the front ADD actuator I see at least one connection.

-4wd fuse looks intact in the fuse box. Any other fuses or relays I can check?

I haven’t yet got to pulling the ADD actuator, but I plan to tomorrow. It’s absolutely dumping snow right now...

Could it be a bad transfer case actuator since I’m not hearing that motor whirring sound? Switch? Tube? ADD actuator? Why did 4wd randomly engage that one time? I honestly have no clue...

Any advice is greatly appreciated and I apologize for what seems like redundant thread, however all the info is so all over the place I’m struggling to find a solution.

My deepest thanks,
Elias

 

Hello my friend. I am in New Mexico....I am having the same issue with my 2nd Gen, 2015. Switch from 2 hi to 4 hi to back my truck up on a small incline in the snow and ice. As I was started rolling forward I switched it back to 2 hi. Heard a louder than normal "clunk noise." Noticed the green light flashing. So I stop and tried to get the light from flashing. Long story. I lost my 4wd... I am in 2 hi but this sucks cause My elk hunt starts on Monday. lol Anyways, from going through the whole 4x4 system what I am now reading it maybe the front actuator, ADD or the ECU. So, I am about to log off and got get my tools and start crawling around in the cold mud and snow but checking the motor on the from axle is good or not. After that it maybe the ECU. This is want I have determined after two days of physically on the truck and now reading posting on this site. "Good luck to both of us!" Please post what you might find with your truck. Cheers!

 

Best of luck to you! Let me know how it turns out.
I’ve continued to hit more dead ends unfortunately. Took my whole transfer case actuator motor apart for inspection and everything looked good and read fine on the multimeter. It was already clean, but I cleaned it some more and reinstalled it. Still no action when I push the 2-4 selector switch.
I’m feeling like maybe the problem is either with the 4wd ECU or the front differential ADD actuator. If it’s the ECU it’s beyond me, and I’m unable to pull the ADD because I can’t get the truck off the ground at the moment. I mean, maybe I could pull it, but it doesn’t seem likely with how tight it’s packed in there.
I have a diagnostic appointment on Tuesday at the dealership. At this point I’m willing to pay the $140 to have them figure out the issue. Really hoping it’s something I can repair myself. Fingers crossed.

I was hoping some more people would chime in here and offer some advice on what else to look at. I have the 4wd wiring diagram for the 2003 (thinking it’s the same as the 2002), but I’m feeling pretty overwhelmed by it. Not sure how to go about testing all the paths... definitely novice experience here, but very tenacious and willing to put in the work.

From all the threads I’ve read, it appears we’ve entered into one of the more complicated systems and the threads kinda seem to just fall off

 

Just to note, I also pulled the “transfer 4wd position switch” on the metal portion of the transfer case actuator. It was clean, but I cleaned it anyway and it read fine on the multimeter. Reinstalled, but yeah, no luck.
A lot of diagrams and photos I’ve seen have two switches in this location, however my specific model only has one.

 

Started to remove the front axle actuator and ran into a big problem. I am going to have to remove part of the lift kit to get the actuator out. Fun fun fun! Stay tune! lol

 

I could not figure how to upload a video so I put one on youtube. Check out the link. Did you get your trunk fixed?
https://www.youtube.com/watch?v=8S7xEXl4Blc&t=2s

 

@Taco_eater2015 That’s awesome! Great job, man!
I’m going through hell right now with the dealership haha. The front actuator broke a tooth so that definitely had to be replaced, but the 4wd still isn’t working. The t-case actuator is working, but apparently it’s not moving the shaft far enough into or out of the transfer case to engage the 4wd. They say it’s probably another broken tooth in the gears causing the shaft to slip. It could be, but I’m really damn curious if it’s because I removed the black plastic section of the t-case actuator and didn’t set the timing right when reassembling it. The contacts are lined up to where I found them when I removed it, however I did notice when I first took it off there was a type of spring-loaded tension that was released. So I’m wondering now if I could reset that tension if it would resolve the new issue of that shaft not moving far enough.

Unfortunately I haven’t found any answers to that query yet...

 

My friend....I will only take my vehicle to the "dealershit" for maintenance. Never again will I have them work on my vehicles for repairs. What a rip off! Did you by change view my YouTube video? https://www.youtube.com/watch?v=8S7xEXl4Blc
Reading your post... Broke a tooth on the actuator....That I can see... being its a plastic type gear. But the transfer case.... It can be believable it's the actuator as well??? But I am doubtful the actual transfer case has issues. They are pretty darn durable. Replace the actuators yourself. I found at https://www.carparts.com is the cheapest. I believe, from my experience Dorman is a decent parts. Again, piss on them dealerships. They don't give shit away for free...and that's for sure! Good luck my friend. Please keep me posted as to what becomes of getting your rig back on the road. On, by the way. I been taking my Tacoma out to the high mountains on the Navajo Rez for my Cow Elk Hunt. Driving through mud and snow daily. Everyday when I get home I have to wash the windows off of mud. Serious overland terrain I am covering. I am doing it with confidence and caution! lol

 

NEVER TAKE THE PLASTIC CASING OFF THE TCASE ACTUATOR! ALL BAD YOUR NIW GONNA NEED TO PURCHASE A NEW ONE AND HAVE SOMEONE INSTALL IT

 

Jayrod666,
Don't believe that crap... I pulled the transfer case actuator off and apart at least six times. It's working fine. I have 2 Hi, 4 Hi and 4 Low.