4wd not disengaging, brown wire mod no help

[Buckshot]

I never post in 911, but I figured I'd ask in case I'm going to damage my front end worse than the 35s are already doing.

Went wheeling this weekend. Lots of sandy creekbottoms and water. Pics later - including a 30ft roostertail of water....Have had to take apart a lot of stuff to clean out the sand. I'll be asking about my interior fan for the AC/Heat soon too....blowing sand in car and making horrible noise like intakes are plugged or motor is being resisted. But my real problem at the moment I think is that 4wd won't disengage.

I completed the brown wire mod a while back and have been using it with a great deal of success. So I go wheeling, connect my brown wire, drop into 4lo and had a great time. After getting back out of the muck and dropping back to Auto, I still get serious binding and poping from the front end when turning. So much so that I can barely overpower it to continue any forward motion. Feels worse than just 4wd on dry pavement, but I haven't done it before with these 35s on, so maybe that will be normal.

With it in Auto and both with the brown wire connected and with it disconnected, I've backed up, gone back and forth from P, D, to N and back, driven 30 miles or so, and used a mallet on the Tcase shift motor. No joy. I just put all four wheels in the air on jackstands and confirmed that my front is still engaged...even with the brown wire disconnected.

1. Everything points to tcase itself since the brown wire should eliminate tcase shift motor issues, right?
2. I'll be doing a Tcase fluid change this weekend, but is there anything else I can use to narrow down possible issues?
3. How long would you drive in this condition on dry pavement before resolving it? Its my DD, so I'd like to keep driving unless I'm doing more damage.

Thanks in advance for the help.

 

[TPLYNCH]

Have you tried disconnecting the battery to try and reset the computer/shift motor. Sounds like it's stuck. You can also remove the shift motor and manually shift it out of 4Lo and back to "neutral". Also, if you haven't already, make sure you didn't break/disconnect any of the wires to the t/f case while you were mucking about.

 

[Buckshot]

Doesn't look like any wires are broken, but I guess I could have stressed one enough to screw it up where I can't see it. But I would think I'd get more indicator lights and issues. As it is, the lights all come on appropriately when shifting to 4hi, 4lo, and back to auto, but the front wheels never actually disengage. The computer thinks the shift motor is working fine.

I'll try the battery first, but I'll probably be taking the shift motor off when I get home if it's not raining just to check.

Is there a possibility that the transfer case itself is mechanically stuck in the "engage" position? How would I go about checking that?

 

[DeRocha]

I believe GJarrett had the exact same problem. He thought it was his T-case as well, but it turned out to be a short in the brown wire mod. If I remember correctly one of the wires he spliced into for the mod had evidently worn through its insulation and begun to intermittently short out causing the t-case to engage 4x4...

 

[Buckshot]

Hmm....I would think that the short would cause the tcase to actually disengage 4wd because interruption of power to the brown wire is what makes it a 2WD mod.

My problem is that 4wd won't disengage. Maybe ole Herc will give me some clues.......

 

[dman726749]

ya can take the d-shaft out as a short fix...tcase motor may be on the way out.......also werent you having troubles with it in jan at haspin?

 

[gijoecam]

As to whether or not the brown wire could be the cause, where EXACTLY did you make the splice?

To eliminate it, disconnect it right at the transfer case. The shift motor doesn't turn anything unless you are going into/out of 4 low. When you click it into high, the TCS relay puts power to the brown wire, which engages a clutch in the transfer case. As near as I can determine, that clutch operates in a similar manner as the one on your AC compressor. Cutting the power to it by unplugging it should, if it's not frozen, release the clutch and disengage the 4wd. That's why interrupting the signal by putting the switch in the brown wire works so well.

On a side note, if you break the wire in the proper spot, you can provide yourself with 2wd low as well, but that's another mod for another discussion.

Back to the problem at hand. If unplugging the transfer case doesn't work (and make sure that the plug has the brown wire in it), you could easily remove the front driveshaft in the mean-time. It's just two yokes at the front, and ummm.... can't remember at the rear, but it's not too bad. For a DD, I wouldn;t drive it like that any longer than absolutely necessary.

-Joe

 

[Buckshot]

Ok - damn its cold outside, but I pulled the shift motor. I see H---N----L settings. Since Neutral is beween H and L settings, and my switch from 4H to 4L still works, I can't imagine it is the shift motor.

What controls the power to the front driveshaft? I cut my brown wire under the drivers seat where the brown wire goes back through the floor. I thought that was it, since if I drop into 4L I used to be able to get 2L. (before my front driveshaft wouldn't disengage!)

Next step is a transfer case flush and fill. But can someone answer my question: Can I manually switch to Neutral? What position should the switch be in to disengage the front driveshaft completely?

I'm going back out to try exactly that, but I figured I'd start the Explorer internet research team (you guys!) on it while I was at it. Thanks for any help in advance!

 

[Buckshot]

Ok - attempted a manual turn of the selector switch the electric motor moves and I get maybe a 15 degree range of motion. Certainly not the range that seems to be indicated by the selector switch.

I have disconnected the battery terminal to reset everything also - but i am highly suspect of mechanical issues inside the transfer case since i cannot turn the switch manually. I get only two "positions" I can feel it clicking in - not three as I have been led to believe.

1. Is this a three position switch?
2. What range of motion should it have?

I'm going to go try the console switch and see how far the electric motor "wants" to turn the switch. This may answer my questions for me. I have been led to believe from other posts that I can "re-align" the switch later once I try this. If not, I guess that will be my next 911 post.....

 

[Buckshot]

Here is what I found out. With the electric motor disconnected, moving the console switch on a 97 with control trac (Auto, 4H, 4L) only changes from 4h to 4l on this transfer case. The electric shift motor seems to have only two discrete positions rather than a continuous selection. The reason I could turn the mechanical selector with my fingers must be one of high torque requirements.

So, the choice of engaging the front drive shaft must be made somewhere else?

 

[dman726749]

the shifty motor does nothing when going from 4auto to 4low...there is a magnetic clutch inside the transfercase that sends the power to the front....when you switch from 4hi to 4low is when teh shift motor is used, switching the gears.

sounds like maybe the magnetic clutch is waht may be the culpret.

 

[Buckshot]

ok - traced it. The brown wire actually does not go into the shift motor. It goes directly into the back of the transfer case. it is a part of the wiring harness the electric shift motor has attached, but only to provide a connection point.

I get .1 amp (in park - I'm sure this would rise as the computer requests more power to the front) using a clamp-on ammeter with the console selector switch on auto and .6 with it on 4h or 4l. If I use the voltmeter at the spot where I spliced in my "brown wire mod"switch, I get less than 1 vlt and with the console switch on 4h or 4l, I get 8Volts.

So, the switch works and if these numbers are correct, nothing is wrong with my brown wire. It has to be a mechanical failure within the transfer case, correct?

So next question - can someone else with a 97-99 and the brown wire mod run voltage checks at their switch and see if these numbers are correct? Meanwhile I'll see if it is on this site somewhere.

 

[Buckshot]

Thanks Dman! I knew I could count on you to keep me from just talking to myself here and getring accused of padding my post count.

That's my assessment also. But I think I have taken this diagnosis as far as I can. Now I need some suggestions as to how to repair this. I'm burning up the new 35s in 4H on dry pavement!

 

[dman726749]

i would just pull that front shaft until you get it figured out......(although you may need it with the snow we are going to get tomorrow :fire: )

also i saw a 1354m forsale over on rrorc..may be a fix and an upgrade for ya.

 

[gijoecam]

Ok - attempted a manual turn of the selector switch the electric motor moves and I get maybe a 15 degree range of motion. Certainly not the range that seems to be indicated by the selector switch.

I have disconnected the battery terminal to reset everything also - but i am highly suspect of mechanical issues inside the transfer case since i cannot turn the switch manually. I get only two "positions" I can feel it clicking in - not three as I have been led to believe.

1. Is this a three position switch?
2. What range of motion should it have?

I'm going to go try the console switch and see how far the electric motor "wants" to turn the switch. This may answer my questions for me. I have been led to believe from other posts that I can "re-align" the switch later once I try this. If not, I guess that will be my next 911 post.....

I can't speak fo the range of motion, but 15 degrees sounds about right. The only thing the shift motor does is engage and disengage the planetary reduction gears for low range. There should only be two positions for it. There may be an intermediate position for it as well, as I know some years have a neutral tow kit available for it which stops the motor in between the positions.

The clutch coil is what engages/disengages the front driveshaft. It uses a magnetic coil and ball/feed ramp assembly to lock and unlock the driveshafts. I've yet to tear one apart to see what makes it tick, but looking at the exploded diagrams, that's my best explanation.

As I already said, if disconnecting the power to that coil doesn't cause it to disengage, your problem is internal to the transfer case. The shift motor has nothing to do with it.

-Joe

 

[Buckshot]

Thanks guys. I think we have a conscensus. Now to figure out how to fix the tcase, or else I may just get pissed enough to put in a 1354 - or better yet an Atlas!

 

[Nate1]

Are you sure you didn't get sand in your front IFS somehow? Is everything well greased etc? I would start from the CV joints and work my way back to the transfercase lubing/greasing/cleaning everything I could.

 

[DeRocha]

Here is Gerald's Brown Wire problem thread. I'm posting in-case others have similiar issues and to help organize related issues together.

 

[Buckshot]

Thanks DeRocha - after reviewing Gerald's thread, I ran one more test and disconnected the entire wiring harness. Unfortunately, that didn't help. Still stuck in 4wd.

And Nweibley - thanks for the advice. Yes I know I need to clean everything again, the extra weight of the sand packed in my frame rails has lowered my suspension 1/2 inch or more and makes an already heavy vehicle feel like Rosanne Barr after a binge weekend even on flat streets. But, even if I got sand in the CV's, I can't imagine why it would keep me in 4wd.

 

[Nate1]

Thanks DeRocha - after reviewing Gerald's thread, I ran one more test and disconnected the entire wiring harness. Unfortunately, that didn't help. Still stuck in 4wd.

And Nweibley - thanks for the advice. Yes I know I need to clean everything again, the extra weight of the sand packed in my frame rails has lowered my suspension 1/2 inch or more and makes an already heavy vehicle feel like Rosanne Barr after a binge weekend even on flat streets. But, even if I got sand in the CV's, I can't imagine why it would keep me in 4wd.

Well my line of thinking is that the front drivetrain is 100% always locked, so if you have sand somewhere in you axle/diff you may be experiencing some binding because of it.

Altough I still think it is the transfercase myself, it would help to isolate out the rest of your front drivetrain and do the inevitable cleanup work that needs to be done anyways to keep it in good running order after a little sand expitidion