Stuck in 4wd - troubleshooting? Fixed!

[thezentree]

2001 SR5 with multi mode t-case.

I’m at the end of a 5 day 4x4 trip with some friends and have been stuck in AWD since midday yesterday, and now I finally have cell signal.

Front driveshaft is locked in and I’m definitely getting power to the front end, but the 4wd dash light is either flashing or just off entirely, even though it’s in 4wd and the 4wd button is engaged. No problem shifting in and out of 4LO.

I can’t lock the center diff, or get it out of 4wd. Putting the shifter in the 2HI pos gets me a flashing dash light and will eventually cause a godawful squeal (sounds like worn out brakes). Stopping and turning the front driveshaft will cause it to lock back in to 4wd.

I’ll be home tomorrow and am going to clean it off and start troubleshooting, but am not sure where to start. I remember reading a good thread about checking the position switches on the tcase and front diff but I can’t find the thread.

Any ideas?

 

[Cree]

Sounds like you lost a position switch on the T-Case. Not sure which one it might be, don't have a diagram in front of me. But there's 2 on the case.

 

[thezentree]

Sounds like you lost a position switch on the T-Case. Not sure which one it might be, don't have a diagram in front of me. But there's 2 on the case.

I’ll pull those when I get home and check them. Just a matter of continuity when depressed and not looking for specific resistance, right?

 

[Wraytex]

That's correct. I used some brake cleaner and vigorous actuations (tapping the ball on the workbench) to clean the contact points until the replacement arrived.

 

[thezentree]

Welp, both switches on the tcase and the one on the tcase actuator test good.

Is there a switch on the front diff I didn’t see?

If not, any advice for checking the tcase and ADD actuators? Is there a separate actuator for the center diff lock?

I saw the little vent tube between the tcase actuator and tcase was disconnected at the actuator, and I got into some pretty deep water the other day, so that doesn’t bode well for my tcase actuator...

 

[Bad Luck]

Welp, both switches on the tcase and the one on the tcase actuator test good.

Is there a switch on the front diff I didn’t see?

If not, any advice for checking the tcase and ADD actuators? Is there a separate actuator for the center diff lock?

I saw the little vent tube between the tcase actuator and tcase was disconnected at the actuator, and I got into some pretty deep water the other day, so that doesn’t bode well for my tcase actuator...

Disclaimer: I have a 2000 which is a vacuum operated front diff actuator. 2001-2002 use an electric front diff actuator.

On mine there is a switch on the front diff.

The transfer case actuator controls the 2hi/4hi/4hi locked shifting and the transfer case shift lever manually changes the high and low transfer case gear selection. My assumption is that your transfer case actuator got water in it and fried. If you can find a pinout for the transfer case actuator you can apply power and ground to the actuator. If the actuator is good then it will shift. I did this on a lift so there wouldn't be any drivetrain binding. You may want to put all 4 corners on jack stands to avoid any drivetrain binding that may be present.

 

[thezentree]

Well, I dumped 2 or 3 ounces of water out of the actuator motor cover, so that'd be the problem.


But, I took the motor apart and cleaned the commutator/brushes and all the rotary contacts in the case. They're pretty pitted from either arcing or corrosion, but some 800 grit sandpaper, MAF sensor cleaner, and white lithium grease later and it works again. Not sure for how long, but it works great. In and out of 4wd and center diff lock without problems at all.


Also, for anyone who might need to replace the actuator, this might actually be possible without having to split the case.

This morning I found this video, which deals with an older style multimode tcase where you can pull the pinion gear on the shift rod out through that little triangular inspection cover. The 01-02 style case doesn't have that cover, so you can't get the actuator off that way. But, when I had the motor assembly off to clean it, I gently tugged on the spur gear with the electrical contacts that's attached to the pinion/shift rod and got a face full of gear oil, so I think you can probably get that little pinion gear out that way and then pull the actuator off the shift rod without splitting the case. Timing it when you put it back together looks like it'd be a *****, but if it'll come off like that, timing is doable and WAY cheaper than splitting the case.