99 Expedition stuck in four wheel drive..help!
 

I have a 99 Expediton that is stuck in 4wheel drive. The truck is in a major bind. It seems as if it could be stuck in between awd and 4x4. Indicator light is not on and there is no power to the switch in side the truck. Fusea are all fine and there is power every where else but inside at the switch. This problem just began, started off with the starter engaging ramdomly then a few of the indicator lights in the dash and the radio would kick on and off. Many crazy electrical things started to happen. I did not even put it in 4 wheel from a4wd it happened on its own. Now can not even hardly turn the truck and it shakes something terrible at about 35mph but once at a high speed it does not shake. The rpms are in normal range while driving but making turns and manuvering makes it feel like I am about to rip the front diff. right out of it. All of the problems with the indicator lights and radio have stopped but still have this issue with 4x4. HELP!!!

Did you check fuse #23?

The Vehicle Does Not Shift Between A4WD and 4WD Modes Properly
4WD mode switch.
Circuitry.
CJB Fuse 23 (10A).
A4WD clutch relay/circuit.
Contact plate sensors A, B, C and D circuits.
Transfer case shift motor/circuit.
Transfer case shift relays.
Transfer case mechanism.
GEM.
GO to Pinpoint Test B .

Here's more info for you;

Principles of Operation

The automatic 4-wheel drive A4WD system is a full time 4-wheel drive system with an electronic shift 4x4 system that allows the operator to choose between three different 4x4 modes. The operator can switch between A4WD, and 4WD high mode at any speed, and 4WD low mode. To engage or disengage low range, the vehicle speed must be less than 5 kph (3 mph) , the brake depressed, and the transmission must be in NEUTRAL.

In A4WD, the generic electronic module (GEM) varies the torque split between front and rear drivelines by controlling the transfer case clutch. The transfer case clutch allows for slight speed differences between the front and rear driveshafts which normally occurs when negotiating a corner on dry pavement. When the rear wheels are overpowered, the GEM detects this slip condition, and the duty cycle to the transfer case clutch is increased until the speed difference between driveshafts is reduced.

The 4WD mode switch is a rotary switch which allows the vehicle operator to choose between A4WD, 4WD high, and low range positions. There is no A4WD lamp, and the 4x4 lamp is controlled by the GEM and tells the owner that the vehicle is in 4x4 high mode. The LOW RANGE lamp is controlled by the PCM.

The vehicle speed signal is hardwired between the powertrain control module (PCM) and the GEM, speed control, overhead message center, air suspension, and EVO steering. The instrument cluster also receives the speed signal, but receives it over the standard corporate protocol (SCP) communication network. The PCM determines vehicle speed from the output shaft speed (OSS) sensor which is hardwired directly to the PCM.

The Hall effect sensors are mounted to the transfer case and are used to determine the speed of the front and rear driveshafts.

The shift motor sense plate, an integral part of the electric shift motor, is used to inform the GEM what mode the transfer case is actually in.

The digital transmission range (DTR) sensor, located on the left side of the transmission, informs the GEM of the transmission gear position.

The 4x4 shift motor relay is a module containing two relays which, under the control of the GEM, shift the transfer case shift motor between the three 4WD modes.

The torque on demand (TOD) relay is used to activate the A4WD clutch within the transfer case by the GEM. This relay controls the torque split between the front and rear axles.

The throttle position signal is hardwired from the PCM to the GEM. The GEM uses the throttle position to anticipate a rear wheel slip condition when the vehicle is in A4WD.

Yes fuse 23 is fine.

To engage or disengage low range, the vehicle speed must be less than 5 kph (3 mph) , the brake depressed, and the transmission must be in NEUTRAL.

This information should be in bold.

I just had my Expy lock itself into 4 Low while backing up, couldn't figure out why it wouldn't unlock while in PARK.

Moto Mel to the rescue!

What's the question?

Need help with a similar issue.

I have a 1998 ford f250 stuck in 4-lo.

There are 2 (relays I think) on the firewall on the passenger side. Each has an electrical connector and two vacume lines attatched to it. On each, only one of the vacume lines has suction.

On the transfer case, there is a diaphram with two vacume lines also. Again only one has suction.

On a possible related problem, the shift know is off. When its in in park, the shift lever shows it in reverse. It is always 1 off to the right.

This is the Expedition/Navigator forum. I think you want this one for a 98 F-250: 1997 - 2003 F150 - Ford Truck Enthusiasts Forums

On my trucks you have to go to neutral and have your foot on the brake to engage or release 4WD low.

my 99 exped is doing the same thing, we didn't put in 4x4 its just stuck in 4 hi
i can shift between 4 lo and 4 hi all day but it wont come out of 4x4

Try unhooking the vacuum line on the passenger side firewall (furthest left solenoid) and see if it comes out of 4wd. If not, go under to the front axel and see if the diaphragm / lever moves. They are known to get sticky. WD40 the lever arm ans pry it back and forth with a large screwdriver.

you wouldn't happen to have pics or a diagram would you?

I'm not near my Expy but I found this video that shows the solenoids.

https://youtu.be/AWXiArMiqBw

And here's the diaphragm on the front axle
https://youtu.be/MJsGeFff838

My wife has a Navigator with the same issue, it's always in 4X

2001 Exp stuck in A4WD
 

I have a 2001 Exp that's stuck in A4Wd. The truck shifts from 4 HI to 4Lo but when I switch it back to A4Wd it doesn't disengage. It does disengage when I pull the fuse 104 under the hood. Any help. Also the same time this happen I lose my overhead temp and compass which when I pulled it to look at it it looks like the display screen is burnt on the edges. thining it maybe something electrical

How can it be stuck in A4WD and still shift into 4hi or 4low?

The burn mark on the display is something that is made during the manufacturing process, and it's completely nornal.

When I shift the selector to 4hi and 4 lo it shifts. I can tell by the way it drives..

When I put it back in A4wd it should be just two wheel drive until the back tired spin..but it stays in a4wd

This is where you're losing me...if it stays in A4WD then how can you feel it shift into 4Hi when you move the selector switch? There is no difference between A4WD staying locked up and 4Hi...they are the same.

Doesn't 4HI lock the transfer case? Or is that only on later ones which also has the 2HI option?

[QUOTE=alloro;15852504]This is where you're losing me...if it stays in A4WD then how can you feel it shift into 4Hi when you move the selector switch? There is no difference between A4WD staying locked up and 4Hi...they are the same.[/QUOT

Okay let's forget that I can feel anything..I do know that my a4wd is always engaged until I pull the fuses under the hood for it

[QUOTE=drk1bowhunter;15852561
Okay let's forget that I can feel anything..I do know that my a4wd is always engaged until I pull the fuses under the hood for it[/QUOTE]
Sounds like when he's in A4WD the Torque on Demand clutch is at 100% duty cycle. The GEM prolly thinks there is a difference in speed between the front and rear driveshafts.
Are there any warning lights on? Like CEL or flashing OD light? Maybe a good scan tool can pull out some B codes?

No lights on until I pull the fuse 104 then the 4x4 light flashes

The TC is mechanically "locked" in 4WD when the selector switch is in A4WD or 4Hi. The difference is that when in A4WD the front clutch (powered by fuse 104) is electrically disengaged until rear wheel spin is detected. When rear wheel spin (RWS) is detected the system powers the front clutch which engages the front driveshaft to give the added traction. The sole purpose of the transfer case shift motor is to switch between 4WD Hi and 4WD Low. Since pulling fuse 104 releases the front driveshaft I suspect there is a problem with a speed sensor, like pdqford suggested, or there could be a problem with a relay, the 4WD circuitry, or one of the contacts in the shift motor. At this point my money is on the shift motor contact since there is no trouble light being flashed.

Thanks I'll look into the shift motor...

Bowhunter
I have Exact problem in my 2000!

[QUOTE=BadBee;15862359]Bowhunter
I have Exact problem in my 2000

I'm still having the problem let you know if I get it fixed

AWD
 

I'll be working on mine this week and will post results!!!Thanks

Did you ever get it fixed. I followed this forum last winter and gave up on mine. I just pulled the 104 fuse and called it good.

I have a 2000 Expedition Eddie Bauer 4x4 with the A4WD/4HI/4LO switch.

I recently replaced the steering knuckles, upper control arms, upper and lower ball joints, wheel hub/bearing assembly, brake hoses, rotors, calipers, pads, tires, and wheels. I used new factory sized wheels and new factory sized tires, and Timken wheel bearing and hub assemblies. After putting it back together i noticed that the sticker on the door frame in the drivers side door. It said that the front tires were to be at 30psi and the rears to be at 35 psi. I set my tire pressures correctly and figured what the hell I'll try putting in the 104 fuse. Guess what!!! It worked!!! Maybe its was the wheel hub assembly, it comes with new speed sensors. Maybe its the tire pressures. I really don't care, it worked!

Now i needed an alignment. I attempted to adjust the camber myself afterwards the automatic 4 wheel drive re engaged and i felt the binding especially when turning. I pulled the 104 fuse again and it didn't stop the binding. I'm taking it in for a professional alignment tomorrow. Maybe this will fix the problem. I'm hoping it's the alignment now. I'll let you know what I find out.

My problem was the same I bought a junkie transfer case for a $100 put it in and shazaam!
It works, the clutch packs were eaten up, now I need a new shift motor as my current one is corroded. Hope this helps!!

Thank You for posting results.
This should help others that had the same problem.

I went in for my alignment this morning. The mechanic adjusted my camber but said my left outer tie rod is bad so he wouldn't do the toe adjustment. I asked about the A4WD problem, he said it's probably the transfer case. He didn't think it was at all related to the alignment. I guess I was just hoping.

I've read elsewhere that others have changed out the transfer case and the GEM computer module and have had no luck. But I might check out the junkyard for a used/junked transfer case. I can't afford a new one at this point in time. I'd hate to get another one with the same problem.

Another option I've read about is the "Brown Wire Mod." I need to look it up again but I believe you have to cut the light brown wire at the transfer case that controls the magnetic clutch. This is supposed to disable the automatic 4 wheel drive while still allowing you to manually switch into 4hi/4lo and back to 2wd (a4wd). Has anyone done this? If so, what were your results?

I had clicking in the dash at the switch so that was ok, check transfer case motor, if that clicks and your doing 0-stuck in gear(4wd) temporary fix take out front shaft, plenty of USED tran cases on EBAY and craigslist, chances are forward clutch pack is disintegrated, my mechanic did the Swap in 2-3 hrs, you have to cut exhaust pipe and reweld it.he charged me $150, it was worth it to me as I didn't have a lift at my disposal, BTW LISTEN TO ALLORO AND PDQ FORD THEY KNOW THEIR ****!!! GREAT GUYS
GOOD LUCK
MITCH

Not sure what year your truck is, or if your selector switch has a 2WD position, but when in A4WD the GEM decides when/if and how hard to duty cycle the transfer case magnetic clutch (which applies engine power to the front driveshaft). When in 4H or 4L the Gem duty cycles the transfer case magnetic clutch 100%, effectively powering the front and rear driveshafts equally.


If you cut the brown wire, the GEM won't be able to cycle the transfer case magnetic clutch at all, so the front driveshaft will never be powered. Doesn't matter if the selector switch is in A4WD, 4H or 4L.

Great information. I will certainly be paying attention to anything those guys have to say. I rocked my truck back and forth until I had it right in the middle with no more binding, then I pulled my 104 fuse again. I haven’t driven it yet so I don’t know if that corrected the issue. I'll probably start looking on ebay for a transfer case after the holidays. No extra money til then. I guess I’ll be pulling the front driveshaft for now. And I’ll look into doing the brown wire mod. Thanks.

I have a 2000 Eddie Bauer 5.4L Expedition with the 3 way A4WD/4HI/4LO switch. Around 135,000 miles.

Thank you much. You post was simple and easy to understand. I was under the impression the magnetic clutch was only for the automatic 4 wheel drive and that the shift fork mechanically locked it into 4wd when selected. I did find a post that described how to do the brown wire mod by alloro: https://www.ford-trucks.com/forums/1...l#post10688108

I was wondering if the brown wire mod could be modified to allow the 3 way A4WD/4HI/4LO switch to effectively become a 3 way 2WD/4HI/4LO switch. I have a more detailed post here: https://www.ford-trucks.com/forums/1...l#post16758087