4wd Will Not Disengage

[GJarrett]

Need help ASAP, I'm 1,500 miles from home.

'99 4x4 Auto system. When selecting from 4 High and/or 4 Low to 4 Auto, it will not release. I have tried every trick from driving in reverse, trying to disengage it from multiple positions and situations, etc etc etc. I am now in full-time 4wd. Ray Lobato and I have disconnected the shift motor and compared how mine operates to his old one that is still on his old transfer case.

The shift motor seems to be operating properly. It shifts from 4 Low to 4 High. Evidently that is the only two positions for the shift motor since it didn't turn a third time for the Auto position on Ray's either. I removed the shift motor and it doesn't have a auto position to move to so we don't think the motor is the problem.

The dash light that reads "4high" and "4low" turns on properly when the selector is turned to that position. The light turns off like it should when I select 4 auto, so it thinks it disconnected it, but it doesn't.

I remember thinking I heard something metallic snap while on the trail before the problem developed. Is it possible to break the Borg-Warner transfer case and have it lock out 2wd?

Does anyone have a knowledgeable guess to what happened?

I need some ideas, fellas. I was supposed to head back for Texas tomorrow morning. I may end up removing my front driveshaft to get home.

 

[leebo]

Gerald,
You had to mess something up didn't you.

I'm sure you've thought of this, did you try to disconnect the battery?

 

[Rick]

From Jeff Singleton's page:

There are Hall Effect sensors in the transfer case on both the front and rear drive shaft outputs. These signals are sent to the GEM (Generic Electronic Module) and the GEM, using additional input signals, drives a magnetic clutch in the transfer case to engage FWD power


This could be the sourc of the problem.

Good luck, I hope it works it self out quickly and inexpensively!

 

[yob_yeknom]

Since it is electric, I'd try disconnecting the battery like Leebo suggested. If that doesn't work, pull the fuses for the 4wd system.

 

[Jason_25]

I say put it all back together. Switch to 4-auto, and have someone tap the case with a hammer. The clutch may have gotten stuck.

 

[BislamJoe]

What? There's a 2wd position?

 

[GJarrett]

Disconnecting the battery and resetting the computer is the first thing we tried. We have also banged on the case with a hammer to try to get the magnetic clutch to release. I can't find a fuse for the 4wd system, though the underhood maxi fuses have a transfer case relay fuse which is still good.

These Hall effect sensor thingies, are they part of the plugins to the Tcase, or are they internal? Is there any way to test the magnetic clutch?

Ray still has his original Tcase sitting in his garage. I am afraid I will have to swap his in tomorrow to see if that fixes it. If I still have the problem after putting Ray's transfer case and shift motor in, I guess that means the GEM is bad; I cannot think of anything else? But if the GEM went bad, wouldn't I have more problems than just this one? I'm not messing with removing a dash; if the GEM's the problem I'll probably end up paying to get it done.

Crap. I gotta be in Dallas on Thursday. The last thing I want to do is swap out a transfer case tomorrow. That top bolt that holds it to the transmission is a motherbear to get to. I'll search those Singleton pages to see if I can learn anything else.

 

[COMMOCOZY]

G-

I just pulled my x-case shift motor. Do this it will only get you 2WD no more 4WD till you get it fixed.


Pull the harrness that goes into the 4x4 **** motor. I did this and i have the Auto 4wd and i was in 2wd all the time.. the computer can't make any readings so you O?D lights will flash but it will get the job done!!!!


I KNOW YOU SAID YOU PULLED THE MOTOR, BUT TRY DRIVING IT WITHOUT THE HARNESS HOOKED UP.



HOPE THIS HELPS

 

[GJarrett]

Thanks, but yep we've driven it several miles with the harness disconnected and it didn't make a difference either.

 

[tdavis]

Pull the front drive shaft, and drive it home in 4hi.

It shouldn't hurt it any..

 

[KEbert]

At this point in your problem, I have to agree. Pull the drive shaft. It should not have any harm.

 

[GJarrett]

Thanks to all for their suggestions.

Yep after sleeping on it, that's the plan for this morning. I think I probably snapped something in the tcase and won't need a whole new one, so I'll pull it once I get back to Texas and open it up and see what I find, then replace whatever is broken.

 

[Robert]

Since pulling the transfer case shift solenoid connector didn't release it, it says to me that it is internal to the transfer case, not the GEM. It looks like you already figured on that, just backing it up.

 

[rpenner54]

Gerald you got it all wrong! LOL

What you are supposed to do is give Ray a few sleeping pills and swap cases with him. He won't know till your 300 miles away! LOL

 

[tdavis]

I'll go out on a limb here.

From you've posted, it sounds like a shift fork broke off, or is jammed.

As for Ryan's suggestion, yup, you missed it big time!

 

[GJarrett]

Hehe, great idea, but....

When Ray volunteered to swap the tcases, I do believe he meant the old one sitting in his garage. He probably would have noticed if his Atlas was missing, lol.

We've dropped the driveshaft and I am leaving for Texas in the next hour or so. Cya later!

 

[Yomie]

Good Luck, let us know when you find out the exact problem