Four Wheel Drive Operation (4WD)

See the operation and power flow of a part-time 4WD front differential and transfer case

Timeline:
0:00 Introduction
0:39 The Toyota JF1A electric shift transfer case and parts
2:58 The front driveshaft (Propeller shaft)
3:05 The front Automatically Disconnecting Differential (ADD) front axle
6:21 Transfer case operation
7:42 2WD mode
7:54 The shift into 4WD mode high range
8:36 The shift into 4WD mode low range
9:50 The shift back into 4WD mode high range
10:09 The shift back into 2WD mode
11:15 Operation of the ADD front axle
11:43 2WD mode of the ADD front differential
14:19 The function of the ADD
15:12 The shift sleeve and fork of the ADD
15:54 Two shafts spinning in opposite directions
16:03 The order of events required to connect the two shafts together
16:55 Shifting the ADD into 4WD mode
19:17 Front ADD actuator electrical signals
20:02 The order of events required to engage 4WD operation
20:40 The order of events required to disengage 4WD operation

Weber State University (WSU) - Automotive Technology Department - Transmission Lab. The operation and power flow of this part-time 4WD front differential and transfer case are very similar to others built by General Motors, Dodge, Ford, Toyota, Nissan, etc. This 4WD System is typically used in 2007 through 2013 Toyota Tundra trucks.

This video helps satisfy the requirements of the following NATEF Tasks:
3.F.5 – 4WD/AWD - Diagnose noise, vibration, and unusual steering
concerns; determine necessary action - Priority Level 3

Questions for teachers:
1. Is this transfer case used on a vehicle with a transversely-mounted engine or a longitudinally-mounted engine?
2. What are the two modes of transfer case operation?
3. What are the two ranges of transfer case operation?
4. How are the modes and ranges selected in this transfer case?
5. The ADD connects and disconnects which two parts?
6. What are the two modes of the Automatically Disconnecting Differential (ADD)?
7. List the order of events required to engage 4WD operation
8. List the order of events required to disengage 4WD operation
9. Tell me one thing you learned from this video

[dzineru]

truly helped me understand why, even after disconnecting the front drive shaft, it sounds like gears are trying to fight each other. Perhaps my spring is failing on that darn fork.

[mattf]

Man this cutout view is so awesome, thanks for this so much

[GulfVet]

These are truly outstanding videos. You are an excellent teacher. 

[yohanksor]

i appreciated cars more knowing the details of how it works and made. thank you for showing us.

[lowellguzman]

Wow! Thank you! You are a scholar and a gentleman! Incredible videos!

[PuzzlePicture]

excellent video and display model, thank you for keeping this video up for us newbies to learn.

[markmason]

Again another very informative video, Love watching Ur classes

[swiftymorgan]

Thank you, thank you, thank you !!! I've tried in vain to understand the drivetrain ( Transfercase ->propeller shaft -> front diff ) by reading thousands of articles and looking videos. But with this 20 minutes video you have explained all very well. Especially the open cutted cases where you can see the concurrent or opposite rotating of the axles / shafts are very helpful.

[aussieshootandhuntadventur]

Jeep chrokee kl 2014 to 2023 has two transfer cases each end on there more serious models. Love to see how it works . Great vid

[rupertgaznabbi]

thanks again, you're the best! will give you Sid feedback after I put it in next summer.

[RocketKidd]

this is a great presentation, I really enjoy every sec of this vid. Even I'm not a native English speaker, I could easily understand what are you talking about. Keep it up sir!

[snells-window]

Excellent informative video. Apart from convenience I don't understand why toyota went with this system over the old free wheeling hubs. If my understanding is correct, with the ADD disengaged (running in 2wd), you still have the internal spider gears turning as well as one axle/cv. With the earlier system, when you unlocked the free-wheeling hubs, you effectively unlocked the wheel from the axle so the only thing turning was the wheel and the wheel bearing; none of the axles or internal diff components rotated with the old system.

[mwwhatever]

I think it's amazing how people come up with this stuff

[jameswatkins]

I really enjoyed your video. Please keep up the good work.

[rahalati]

Excellent demonstration, thank you so much

[rolandhumphreyofosu]

this is an excellent delivery. Its simply awesome. I am currently transferring my 2005 Toyota Tacoma from 2WD into 4WD. I already replaced my engine and transmission with 4WD transmission with the electric shift actuator. I am currently running cables to the motor to get it to engage into differnt modes, i have the selector switch here with me. the front axle has also been installed with its shifter actuator motor. Kindly assist me with how to connect the electrical wiring to get them properly setup.

[sindhengineering]

Sir are u great explaind for everyone works u are best teacher thank

[kurianauto]

Very nice explain sir.hopfully u would able to upload this type of many advance technology video.thn u, and also congrage u for under stand me this type of system.

[othonastselikakis]

Excellent video... you explain all very nice 👍 !!!

[josephlecheminant]

Very helpful as I’m trying to figure out why my 4wd is being noisy. The noise goes away as soon as it’s back in 2wd. Now I see what moves in 4wd and what doesn’t move in 2wd. I have a 2005 sequoia.
So looks like the noise could be the transfer case chain, the front prop, or the ring gear of the front diff?

I checked/changes fluids already..
If you happen to see this comment I’d love any additional insight!