How to: Rebuild 4X4 Shift Motor

[adamsbro2]

I took my shift motor off and mine is slightly different than the picture below. In place of:
2H I have H
4H I have N
4L I have L

I would assume leaving the selector in "N"/"2H" is 2wd, correct?

And I would tend to agree N is meaning the transfer is in neutral doing nothing H is 4x4 high and L is 4x4 low range! I'm not positive but I would bet on it! The awds usually have an auto 4x4 not really a neutral. I think!

 

[Russ in CT]

Help! Stuck in 4x4. With the shift motor off, can't manually rotate the xfer case into 2H. I can turn it past 2H, but it won't click into place. Soon as I let go the pliers, it spins back to 4H.

2002 Ex EB, ~200K miles. Went to drive it, found it was stuck in 4x4. Had driven it earlier in the day, it was fine then. I haven't used 4x4 in a while (no snow last winter).

Truck has never gone into 4L since I bought it at ~115K miles. Now that its also stuck in 4x4, I figure its the shift motor. Took it apart, everything looked perfect. Hooked it up to 12V, motor spins fine. Cleaned it and replaced the plastic bushing for good measure (bushing broke anyway when I went to remove it).

So while I had motor off, I thought I should manually shift xfer case into 2H while I had the opportunity. To my dismay, I was not able (as mentioned above, can turn shaft, but it won't stay in 2H, just spins back to 4H).

Note, on my 2002, the shaft is actually labeled H - N - L (I presume H=4H, N=2H, L=4L.)

So I put the motor back on anyway, problem still not resolved. I have a spare Control Module (new from dealer, correct for my VIN), so I replaced it just to rule that out.

After the new module, when I first start the truck, 4x4 dash light flashes several times then turns off. But its still stuck in 4x4 (as indicated by trying to turn on pavement).

Its not the shift motor, its not the CM, is it the xfer case itself? Do I need to replace the xfer case? Should I attempt to rebuild it myself, buy a rebuilt one, buy a used one? Looking for advice.

Oh, one more thing, in my hours of research on ExplorerForum, I saw several posts that mention the ABS light. Interestingly, mine has been on intermittently for a few weeks. Haven't had a chance to look into it. Related?

 

[mekaneck]

You may want to try lifting an axle off the ground (front or rear, doesn't matter) and then try switching the selector with your pliers. There may be too much torque wind-up for the xfer case to switch.

Also as noted in the posts above yours, the H-N-L xfer case markings are more likely 4high-Neutral-4low, meaning you have an AWD system different from the 4wd sytem being talked about here. There is probably a disconnect for your 4wd somewhere else (front diff? Automatic hubs?) that is not disconnecting properly, and therefore keeping you in 4wd.

 

[Russ in CT]

Thanks, will try lifting an axle, and putting trans in Neutral.

Is this thread exclusive to 2nd gen Ex? Never saw that spelled out in the thread.

If my hubs (which are auto) were stuck, that would just mean I would be spinning the front axle and front driveshaft unnecessarily, right? I wouldn't actually still be stuck in 4x4 unless the xfer case was engaged, locking front and rear driveshafts, right?

 

[Russ in CT]

ok, all 4 corners on jackstands, I can move the xfer case shaft now. What I found is, the N really does mean Neutral, not 2H as I had assumed. There is no detent for N, anything that is not or L is just a free floating Neutral space. When xfer case is in N, even though trans in D (or R, or anything else), wheels don't move.

So H is for both 4h and 2H. Like Mekaneck said, something else controls 4x4. I'm guessing its a duty cycle signal thing to the xfer case, like I've read some of the older Ex's use (mines an '02).

So if putting xfer case into H is always giving me 4H, then something thinks the rear wheels are slipping, and is trying to engage the fronts to get traction. I'm guessing that the ABS sensors are also used to tell computer when rear wheels are slipping, so it knows when to duty cycle the xfer case into action.

So I should be looking at the ABS system, not the xfer case, I think. Interestingly, I was getting an ABS dash light for a week or two before this stuck in 4x4 thing started.

So it has to be the front ABS sensors, right? No signal = it thinks those (front) wheels aren't turning so it duty cycles the xfer case trying to see them move? (to get the symptom I have, it would have to think rears are moving, fronts are not). Should I just change both front ABS sensors, or is there an easy way to troubleshoot them?

Can anyone tell me if I'm even on the right track here?

 

[Russ in CT]

OK, futher research tells me the xfer case uses speed sensors mounted to xfer case, one for front driveshaft, one for rear (ABS sensors used for traction control and AdvanceTrac, which I don't have).

So either I have tire size differences (uneven wear), or bad speed sensor(s) (I think).

How likely is it the speed sensors go bad?

 

[Russ in CT]

Tire sizes all check out. Used string to measure, all exactly the same.

Is there a way to temporarily disable the 4x4 so I can drive while I figure out the fix? Tried pulling fuse 17 & 18 (20A) under the hood, that control 4x4. Tried unplugging 4x4 CM. Still stuck in 4x4.

Is the xfer case default mode 4x4, and the CM tells it how much to unlock to go into 2H?

 

[mekaneck]

First of all we need to figure out what type of 4WD or AWD system your explorer has. What buttons are on your dash? 4x4 auto, 4x4 high, and 4x4 low?

Assuming the answer is yes, then my diagnosis is that the viscous coupling (VC) in your xfer case has seized. If this is the case, there is nothing you can do to put your explorer in 2WD, short of removing the front driveshaft.


The VC is contained within the xfer case and does not operate via any electronic inputs. It is merely a coupling that transfers torque based on the relative difference in speed between its input and output (front and rear driveshaft). Basically like a miniature torque converter. If the input and output are rotating at the same speed, there is no torque transfer. If there is a significant difference in speed, the vicsous fluid in the coupling heats up and tries to lock the input & output together, creating torque transfer. For example, if your rear tires start spinning, the VC will heat up and transfer more torque to the front driveshaft. If the VC has siezed, your front & rear driveshafts will be locked together, making your explorer a full time 4wd machine.

See this thread for more info on the BW4404 xfer case:
http://www.explorerforum.com/forums/showthread.php?t=225515


Edit: Upon further investigation, I think my diagnosis may not be correct. Firstly I'm not certain you have the BW4404 or BW4405 T-case (the only ones with VC's). Secondly, even if you have a VC, there must be another mechanism in the t-case which locks the 4x4 on, for when you are not in "4x4 AUTO" mode. I haven't figured out what this mechanism is, but that would be another avenue to pursue.

 

[Russ in CT]

I think your Edit is correct. I do not believe I have a VC xfer case. I was under the impression the AWD Ex's had those. 4x4 Ex's (I have 3 buttons, 4x4 Auto, 4x4 High, 4x4 Low) I thought had locking xfer cases. The 'Auto' mode accomplished by sensing wheel slip and auto locking the xfer case (along with auto hubs).

I believe my xfer case might use a mag clutch, variably activated by a duty cycle signal sent from one of the modules when slip is detected.

I believe my problem is a faulty sensor misleading the 4x4 system into thinking there is rear wheel slip, hence it activates 4x4. The question is, is it the speed sensors on the xfer case or the ABS sensors (or both) that tell the 4x4 system if there is slip?

Gut would tell me its xfer case speed sensors. Otherwise, why do they exist? But oddly, I had an ABS light on intermittently for the past 2 weeks, which seems suspiciously related.

If I could drive it, I could get the ABS codes pulled, and at least correct that, which would rule out that as the 4x4 locking issue (or fix my problem).

Anyone know how this system really operates?

 

[Russ in CT]

Found someone that knows how this system really operates. Check out the last page in this very informative link:

http://www.rsgear.com/articles/2008_05.pdf

If you do not have stability control (like me), the xfer case speed sensors do all the work of detecting slip between front and rear. With stability control, the ABS sensors do the task, and xfer case speed sensors do nothing. In 2005 they eliminated the speed sensors, since by then all Ex's had the stability control standard.

Link also mentions ground strap needed if aftermarket gasket (without metal washer inserts) used between trans and xfer case (like when trans rebuild done). Read that posted here as well.

This doesn't make sense to me. You've got metal bolts with its head making metal contact to trans, that same bolts threads making metal contact to xfer case (or maybe its the other way round. Etheir way there are several of these bolts). So regardless of gasket material, how could the gasket disrupt the electrical path?

Plus, on my shift motor there is a factory ground lead on one of the mounting bolts. The bolt head touching the shift motor, then threads touching the xfer case, hence xfer case, shift motor & ground lead all electrically connected = grounded xfer case, no?

I will get under there and measure resistance xfer case to ground to make sure its well grounded. I'll try removing the ground lead to see if it makes a difference. Just for curiosity, and to see if I would benefit from an added xfer case to ground strap.

Meanwhile, my actual issue(s). Seems like ABS light is not related to my 4x4 lockup, and my issue must be a speed sensor? (its not shift motor, not 4x4 CM, yet 4x4 system thinks rear wheel slipping and sending power to front = speed sensor issue).

 

[Campnham]

I've been reading thru almost all 25 pages of this thread with no luck finding a fix for my shift motor problem. While I was going thru some hints with a flashing 4x4 light, I had removed the shift motor, and had it disassembled. While I was under the hood tracing the brown wire, my neighbor thought he was helping out by re orienting the selector switch on the end of the motor gear. Now it's lost it's way home & can't find 4 low. How is the easiest way to get everything 'happy' and functional again????

 

[Campnham]

Bump..

 

[2000ranger]

Thanks for all the time and effort put into this how to Brian. I also had the dreaded blinking 4 high 4 low lights in 6 repetitions and aprox 2 minute pause and no 4x4. I spent many hours messing with this thing and I was pulling my hair out. I then had my truck hooked up to verry good scanner at a local garage and it could not communicate with the 4x4 computer or GEM 368$ replacement cost at good ol ford dealer. Being a classy no nonsense garage Jim's spent over 6 hours checking the selector switch,fuses and grounds to this GEM of a black box and at no charge as he did not find any problem other than the lack of communication with the computer yet all other perameters of the truck were accessable, Ford would have bled my wallet dry. Thank's Jim the world needs more garages like yours. Now how is any one to diagnose a 4x4 issue when you cant talk to the 4x4 control center? What an engineering marvel 1/16 of an inch on that little bushing can throw the computer in to default and render the 4x4 useless..and dissable communication between the GEM and scan tool. I did take of the shift motor last night and spun the bushing as you posted and presto the 4x4 works in all positions. I now have 4 40 foot bear patches in the midle of my lawn lol. I didnt think it would be my issue like i said because there was so little wear on that bushing but much to my surprise it did. Thanks Brian and Jim you are true mechanics and dont rip people off, dealer ships would prosper by having people like you in charge of customer service. Thanks again 2000ranger

 

[discord]

I was going to troubleshoot the transfer case motor on a 92 ford explorer. I have the automatic locking hubs, so I think I have an electric shift motor. The 4 wheel drive is not engaging. Before it went out the 4 wheel low light would not come on. Now the lights will not come on at all. Is it worth trying a rebuild?

 

[Jonboy2002]

WAY friggin better than a Haynes manual... especially after a few beers. Thanks for the help!!

 

[compnecessity]

Transfer case motor will not pull off.

I removed the 4 bolts, the motor assembly rotates freely as in I can push the motor assembly upwards towards the sky. I can fell tension, but won't pull off to come loose. It's almost like it's bolted on under the blue plastic cover. Not any room to shove in a large flat blade screw driver to pry off.

I have to be missing something right?

 

[Stig]

Fantabulous right up... I noticed the other day if I lightly tap the trans-motor mine works fine.. this is exactly what I was looking for.
Now, can you do a write up on finding where all of my time went, so I can work on such matters? Thanks!!!

 

[cpdad93]

I took my shift motor out of my 1994. It had a heavy black ring from the brushes that cleaned right up....I bench tested it and it runs fine in both direction...Put it back in and still nothing but clicks behind the seat. My next thought obviously is that its lost and not sending signal as to where its out. The problem my gear cover is different. It is plastic with three holes in it so not a lot of room for rotating it (next to none) and I can't see the little board as its apparently inside a sealed unit unless there is a way to pry the plastic open. Any ideas? Thanks, on.

 

[DeRocha]

To re-synch the shift motor:
Remove the shift motor and turn the T-case selector shaft to 4H. Reinstall the shift motor case and geared sensor ( the bolts won't initially align). Turn the shift motor so the bolts align and button it back up. When you turn the truck on the 4x4 system will see the position somewhere in between 2H and 4H. When you press 4x4 it will move to the correct position.

 

[Fowlbal]

Shift motor position sensor on '94 X

Everyone agrees great write up and very informative posts. Wow, 25 pages over how many years, and still going. I got mine fixed today (I think) after pulling the motor and doing all the tests. Turned selector shaft manually, motor ran fine both directions,bump stop replaced,trouble all seemed to be with position sensor. Continuity check between #10 yel/w and #'s 9 or/w, 8 brn/w, 7 w, and 6 vio were very erratic, some were made all the time, some never made. My problem was getting the plastic sensor apart as it seemed to be a sealed unit as several members have noted. With nothing to lose, I pried & cut it apart where i thought it over lapped & snapped together. Tore it up pretty bad, but sure enough the round circuit board with the contacts was loose from the center post it rides on. Looked to just be glued on, so i just re-glued trying to line it up as it was. Also the little contact arms inside, that ride on the circuit board were bent up a little, I straitened them best i could trying to put more pressure on making better contact. Snapped & pried it back together, (tore it up worse) never expecting it to work. Ran the continuity test again, seemed to read ok, re-assembled & installed on X and low & behold it worked. Hope it gets me thru the winter, trying to decide on rebuilding one or buying new for spare. Thanks to Brian, and all members for the good info. on this great site.