Strange 4WD Engagement Issues

[theonlycola]

Hey all, I've scoured the forum and haven't been able to find anything similar to the issue I'm having so here goes:

(2001 4runner SR5)

A few weeks ago I attempted to shift into 4WD with the 2-4 selector switch and the indicator lights just kept blinking. A few days after that the button was still depressed and the car did shift into 4wd but I could not shift is back to 2H. Here are the test and symptoms.

Verified ADD actuator was working by jumping it (done)
Verified T-case actuator functioned in both direction by jumping (done)
Checked all indicator switches on T-case for continuity (done)
Checked 2-4 selector switch for continuity (done)

At this point I know is is an issue with the T-case actuator receiving the signal to shift back into the 2H position. I can jump it back into the 2H position and the ADD subsequently shifts so I know the indicator switches are working between the two actuators. The 4wd ECU also appears to be in somewhat operable condition because when the 2-4 selector switch is depressed the T-case actuator shifts and 4wd is achieved, however the indicator lights still flash. All this leads me to believe its an electrical issue but I don't really know where/how to start testing. Any help would be awesome!

 

[wake_rider]

Going through a similar issue, so I'm here to ask rather than give advice. My apologies.

How are you "jumping" the actuator to be certain they're working?

 

[theonlycola]

I jumped them using a 12v battery with some alligator clips on wires. Jack the car up so all 4 wheels are off the ground. For the front diff actuator I applied power to terminals 2 and 6 and could verify by spinning the tires that the diff was locked/unlocked. Same process for the T-case actuator except it is terminals 1-2. If you’re not sure which terminals to jump just look for where the thicker wires are on the plug. You should be able to hear the motors spinning in the actuator, if they aren’t try giving the driveshafts a spin and the gears might engage.


Sent from my iPhone using Tapatalk

 

[theonlycola]

Update

Update to the pending issue:

I am able to get the 4runner into 4H (center diff unlocked) by:

1) Jump transfer case actuator into 2H position
2) Plug connector back into tc actuator
3) Turn car off/on (causes ADD to shift into 4H position)
4) Press 2-4 selector switch to 4wd position
5) 4 green lights appear

At this point the car will continue to shift back and forth (4WD to 2WD) a few times by itself when i push the selector switch, however after a few shift cycles it sounds like the T-case actuator is not fully locking and i have to resort to the steps above.

I measure the voltage at the connector that powers the actuator and it read only 8V.........could this be the problem?

If anyone has info/experience with electrical problems in the 4WD system I would really appreciate some help.

 

[jgue467]

Have you changed diff fluids? My 01 was 'stiff' at best a few years ago. It would shift in/out with a struggle and few minutes. A couple diff fluid changes and repeated attempts especially including a mild turns yielded consistent in/out of 4wd. It's on demand now, i think po didn't ever use it.

Luck and enjoy that runner. :cowboy: