PLEASE HELP!!! 4 Wheel Drive Intermittent

I have read most every forum on the page for second gen 4 wheel drive problems. Here are my problems- (2006 TRD 6 speed)
- When the trucks cold, it shifts in and out of 4 hi and lo quickly with no issues.
- When you drive around in 2 hi for a while, (about 20-30 minutes) the truck will not shift into 4 hi. (flashing light)
- I can hear the relay click in the dash and the actuator under the cab working but I don't hear the front diff connect. Truck will not shift into 4 lo during this time.
- Park the truck for about an hour, go start it and it will shift into 4 hi and lo again and once again will repeat the problems after driving in 2 hi for the same amount of time.
HERES WHAT I'VE DONE
- I pulled the front ADD and soldered the connections, and cleaned everything up.
- Lost some fluid when I did the ADD so I made sure to pull the fill plug and pump more fluid in there
- It shifted in and out of 4 wheel drive after I did the pull the ADD with ease but after driving for the same amount of time (20-30) minutes the same exact symptoms occur as above.
- I can occasionally get the truck to shift into 4 wheel after driving for a while but I have to play with vehicle speeds and keep flipping the switch back and fourth. This still does not always work.

I can definitely hear the transfer case motor working. There was one time this winter where this issue occurred an there was no way I was going to get out without 4 wheel drive so I got under the truck and banged on the TRANSFER CASE motor and I was then able to get 4 wheel drive to go in.

If anyone could please shed some insight, I love my truck but this is starting to make me lose my mind. I need 4 wheel drive and want to be able to depend on it when ever and never have to worry about it. Thank you in advance.

 

If banging on the transfer case helped, and you can hear the t case actuator going, that would suggest to me that whatever switch that detects the state of the transfer case is faulty. I don't have a wiring diagram , but that is where I would start looking if I did.

 

Thanks, I think that might be where my problem lies, I will take a look! if anyone is having similar issues I found a great write up on Toyota Nation.

-https://www.toyotanation.com/threads/2nd-gen-tacoma-with-4x4-issues.726161/

 

Did you ever end up figuring it out? I’m having the same issue. 4wd works when cold, but after driving a while and truck warms up, it will not lock in.

 

If you want to definitively figure out the issue.
We have a great thread here on TW that goes over the entire process of diagnosing the 4WD system. Don’t be intimidated by the process, we’ve helped many people with it. We don’t care to walk you through it. We do ask that you read the entire post first, then ask any questions you may have.
Once you get us your voltage reading, we can help further there assist you.

Voltage reading chart is in the link.

You need a voltage meter, a sewing needle or paper clip, pen and paper.

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

 

https://www.tacomaworld.com/threads/lets-see-your-fj-case-swap.455278/page-136#post-28806736

 

I have a 1999 toyota tacoma, had same issues, 4 wheel drive only worked when cold and after 20 to 30 minutes of driving it would not engage anymore and periodically it would engage when hot. Changed the actuator, same problem, finally today I tested my vacuum solenoids on the fender wall , one was not clicking when I ran wires to it from the battery. Changed the two solenoid and now it works fine, 4high and 4 low drove around for 2 hours engaging it and disengaging. So those who have problems check your solenoid first, it's an easy fix, easier than changing the actuator.

 

I have to note that this only applies to earlier 1st gens 95 to around 2000, later 1st gens and all 2nd gens have electric actuators on the ADD.