Transfer Case Issues (BW4405)

[hoobs1]

The first true snow storm of the winter came this week and the 4x4 feature on my 96 Explorer decided it would be a good time to stop working . I got the famous 6 blinks of both 4Auto and 4 low. I was able to get the transfer case to mechanically shift into 4 low but I clearly was getting no traction from the front wheels in 4low either.

So I've got three things I thought I should look at after searching on this site:
1: Speed Sensors (Hall Effect)- sounded like the simpliest fix. I found the rear speed sensor (just above the fill and below the rear drive shaft), pulled it out, and everything looked OK. However, this transfer case apparently has two speed sensors. I was unable to find the speed sensor for the front drive line. Can someone give me details on where this is located and what it looks like? Is it on the shift motor side of the TC or the engine side??? Pictures???
2: Shift Motor - The shift motor is obviously working (or at least moving) since I can hear the normal klunk when I move it into 4Low and the TC is cleary in low. At least that's what I'm assuming. Can someone please verify this or is something in the actual transmission shifting and this is what I am hearing? I read some of the threads and it could be that the GEM is getting lost. My bets would be the infamous stop is broken or the contacts are corroded.
3: It could also be that the vacuum disconnect axles are not engaging properly. Of course this sounds to me like a mechanical issue and it should result in 3x4 drive first (odds are both wouldn't go at the same time) and no blinking lights in the dash so I am not ready to pursue this option. Does this sound right?

So anyway, I want to pursue the speed sensors first (#1) which means I have to find the second speed sensor (a picture or diagram would be greatly appreciated). If that doesn't look bad I'll dig into the shift motor. Any other ideas???

 

[budwich]

The other sensor is hidden by the shift motor. If you unbolt it, you will see the same plastic "plug" that you examined by the fill hole on the other side.... follow the wiring.

As for your other questions, hopefully some one will add.... but my 96 experience (same flashing... happens once I get over 60km/hr).... it probably is a sensor issue. I haven't fixed mine as I couldn't get the dam sensors out... seems frozen in place and I broke most of the plastic around it and it still won't budge. My lows work fine which is all I need when I use the system.

 

[hoobs1]

Thanks

I was afraid of that. I guess I'll just remove the shift motor and tear into that at the same time just to make sure that all looks good.
Thanks, for your reply!

 

[hoobs1]

Help!!!

I pulled the shift motor and speed sensors and surprisingly everything looked good. The bushing looked fine and the gears were fine. I'm not sure how to open the blue cover to expose the contacts. Can some explain this so I can check it out? Also is there anyway to verify the speed sensors are OK? A resistance check or something?

 

[hoobs1]

Help please!?!? 96 Explorer with BW4405 Control Trac

After reading about my issue for another 2 hours on the internet and some more work under the truck I have been able to verify the following:
1.) It is not the shift motor, I took off the shift motor, opened up looked for all the usual issues and it was in great shape. I directly hooked it to my battery and it worked perfectly in both directions. I also verified the continuity of the 6 contacts which give location. Also the truck shifts into 4 Low properly and I'm assuming 4auto as well but I don't know how to verify this. Thanks for all the excellent posts on this issue.
2.) Electronic Clutch - is working fine (I think-somebody please confirm this for me!!!). After reassembling the shift motor I verified that the famous brown wire had juice when in 4 low. It had a consistent 2 Volts. Also I grabbed the front drive line and could only rotate it 90 degrees or so. This seemed like too much to me but both front wheels were in the air and in regular 2 it rotated freely. I'm guessing that 90 degrees of motion/backlash is normal in low??? Can someone confirm??? BTW now that I know of the brown wire due to some great posts I will soon have 4High on my truck that is assuming I get 4 anything working first...
3.) Vacuum Disconnect Axle - I now realize I only have one of these and it is on the passenger side (that's good to know). It appears to me that it is not engaging as I raised the front and was in 4 Low and I was able to turn both tires freely (they did not rotate the other tire or the front drive shaft which was locked due to the electronic clutch in the TC being engaged). I'm not an expert with open differentials but I'm guessing that if the vacuum disconnect axle was engaged and the front drive shaft was locked (which I verified it was) moving one tire would have to cause the other tire to rotate or I would not even be able to move the tire, not sure which one but it must not have been engaged. Can someone please confirm this???

So now I need to read about potential causes of the vacuum disconect axle not engaging. Links to any previous threads which would help would be greatly appreciated as I'm not sure if this could be a mechanical issue or a vacuum line problem.

 

[IZwack]

I'm not an expert with open differentials but I'm guessing that if the vacuum disconnect axle was engaged and the front drive shaft was locked (which I verified it was) moving one tire would have to cause the other tire to rotate or I would not even be able to move the tire, not sure which one but it must not have been engaged. Can someone please confirm this???

Thats correct. Assuming the front driveshaft is not able to turn and that the vacuum disconnect system is working properly, if you turn one wheel, the other wheel should rotate in the opposite direction.

 

[hoobs1]

6 Flashes of 4WD Lights – Axle Disconnect

Well, I finally solved my issue. Thanks to everyone who has posted mods and repairs in relation to the Transfer Case, Shift Motor and front Drive Axle Vacuum Disconnect. All the information on this site is amazing and it makes it so easy to trouble shoot when you know exactly what does what. Of in particular use to me was the mod on Manually Controlling the Axle Disconnect and the Brown Wire mod which I will be doing shortly. So here’s my complete story…

As I mentioned the first snow storm came and my 4wd lights started flashing 6 times. When you search this everyone says it means you have a faulty speed sensor. Well I found out that is NOT necessarily the case. The 4wd flashing lights either has additional error logic or it is simply detecting that the system cannot get the two speeds to match (front and rear drive lines). I am of the opinion that it has additional logic due to the thread on manually controlling the AD and what they said about having to wire the sensors properly to trick the GEM…morale of the story don’t go straight into the speed sensors first as one is not easy to get to and there could be a simpler fix.

I should have known better but I first pulled the shift motor and rebuilt it. Luckily I didn’t see any issues with the speed sensors and nobody could tell me how to easily check functionality so I left them (instead of buying new ones) for the time being and put the shift motor back on. Then I did what I should have done first. I put the front wheels in the air, shifted into 4L and left it in park. I verified voltage to the Electronic Clutch in the TC (thanks to the knowledge gained from the brown wire mod) and verified that the front drive shaft was engaged. However both front wheels turned freely (they should have turned opposite of each other if the AD was engaged). So I knew what the issue was and had wasted my time under the truck…

Next I unscrewed the bracket holding the 2 solenoids (see Manually Controlling your Axle Disconnect Thread) in the engine compartment and found the bottom lines had a vacuum but neither of the top lines would get a vacuum in 2wd or 4wd. Next, from the Manual Disc Thread I learned that the larger 5 pin connector had a purple wire which supplied the power and should always be powered. I checked it and it had no voltage. There’s my issue…but why? First I thought about bypassing power into it and putting on the switch discussed to get a manual disconnect but then I wondered if I got a fuse for that??? I pulled about three 4x4 related fuses and bingo, fuse # 26 was fried. It also controlled the rear defrost (hadn’t used it this year as I got a garage this summer) and the manually locking of the doors when you take your foot of the brake (noticed that a few months back but didn’t care about it). The book also says it controls the backup lamps so those most have been out too and the A4LDE Trans? Oh crap , I wonder if that is why my OD switch stopped working 2 months ago???? I’ll have to see if that works now too.

Anyway morale of the story if you have a front Disconnect Axle issue or your 4wd lights are flashing check fuse 26 first…it can’t hurt!

 

[budwich]

Your post got me thinking about my "flashing 4w auto" lights. Not quite your symptoms but I was wondering overall about the operation.

couple questions.... when I put the thing in 4w lo, it does the loud clunk and certain runs in 4w drive as it climbs up stuff (ramps, snow, ice). I assume this "clunk" is good.... right???

when I put the thing in 4w auto, there is no clunk and it doesn't appear to be in any kind of 4w anything as my rear wheel spins (on ice) yet the fronts don't appear to do anything. should there also be an initial clunk of engagement when going into 4w auto?????

I haven't checked the vacuum lines yet but since the 4w low seems to work, I would think there is something there.