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Explorer stuck in 4X4 High??

Joeetogo90

Member
Joined
October 5, 2016
Messages
26
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City, State
Ripon, WI
Year, Model & Trim Level
2001 Ford Explorer XLT
Hello,

I recently posted a thread about a nasty vibration with my explorer while accelerating and I noticed something with my 4X4 system and I'm not sure if this is an issue or not. I have a 2001 Explorer XLT (4.0l SOHC) and when I bought it the 4X4 lights would flash about 6 times every couple of minutes. When you would try to engage the 4WD nothing would happen. I ended up disconnecting the battery and when it was reconnected, the lights stopped flashing and you could here a clunk sound when it would switch from 4x4auto to low and when you switched it back from low to high and auto. It seems that ever since that happened, my truck started vibrating while accelerating and it's mainly noticeable when going from 25-50 mph then it kind of mellows out. I decided to take of the transfer case motor and noticed that there are 3 positions: L, N and H and the metal thing inside the transfer case is pointing to H so I'm assuming it's in 4X4 High even though the dash switch is in the automatic position. I grabbed the front drive shaft and i can rotate it left or right quite a ways before it stops. If the dash switch is on 4x4auto shouldn't the transfer case be in the N position(which I am assuming is neutral). The roads are dry here so there are no slick spots on the roads. I tried putting it from Auto to Low then back and you can here it engaging and disengaging but I don't think it's working properly. When it's in Low, the tires bind when I make tight turns but when I switch it to Auto the tires to do not bind even though the transfer case shows it's in 4X4 high. I do notice a whining sound from the truck when I accelerate also and I thought maybe this was a sign it was stuck in 4x4 besides the fact the transfer case is possibly showing that I am.

IMG_0738.jpg
 



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Well I don't know if this helps or not but I put my phone on record and put it under the front driveshaft, drove back and forth in a parking stall but the front driveshaft is spinning even though the selector on the dash is in Auto 4X4
 






...When it's in Low, the tires bind when I make tight turns but when I switch it to Auto the tires to do not bind. .
Firstly, from your owner's manual:

"The vehicle should not be operated in 4WD HIGH and 4WD LOW on dry or merely wet pavement. Doing so will produce excessive noise, increase tire wear and may damage driveline components. These modes are intended for use only on consistently slippery or loose surfaces."

It sounds like your vehicle works fine in Auto if it does not bind. Four wheel drive vehicles will always bind when locked down in turns on dry pavement, that is when in 4HI or 4LO.

In Auto, your electronically controlled transfer case varies the amount of lockdown of the front axles, thus allowing turns to be navigated.

4HI is the same as Auto with front axles electronically commanded to maximum engagement = locked.

Your transfer case has a motor that mechanically changes between the high and low range. In Auto and 4HI it will be in the high range. Switching to 4LO commands the motor to rotate through neutral and to low range on your transfer case and also continues to command the front axles to maximum lock up.

It appears your transfer case is functioning normally.
 






...the front driveshaft is spinning even though the selector on the dash is in Auto 4X4

Again, this is normal. In auto your electronic transfer case automatically varies the amount of lockup of the front axles. The percentage of lockup is varied between a minimum and a maximum amount based on various sensors. At minimum, they still turn some.
 






Firstly, from your owner's manual:

"The vehicle should not be operated in 4WD HIGH and 4WD LOW on dry or merely wet pavement. Doing so will produce excessive noise, increase tire wear and may damage driveline components. These modes are intended for use only on consistently slippery or loose surfaces."

It sounds like your vehicle works fine in Auto if it does not bind. Four wheel drive vehicles will always bind when locked down in turns on dry pavement, that is when in 4HI or 4LO.

In Auto, your electronically controlled transfer case varies the amount of lockdown of the front axle allowing turns to be navigated.

4HI is the same as Auto with front axels electronically commanded to maximum engagement = locked.

Your transfer case has a motor that changes between the high and low range. In Auto it will be in the high range normally. It appears your transfer case is functioning normally.


Thanks for the Response!

I don't ever intentionally drive it on a dry surface with the 4X4 on except for trying to figure out what was going on here.. When I bought this vehicle from a friend, they were told the transfer case motor was shot, which was causing the lights to blink on the dash. The battery disconnect seemed to fix that but now I have a nasty vibration when I accelerate, which can be a completely different issue, but I just find it weird that it all started to happen after the 4x4 system started working again. In Low the vibration is gone, but in high it remains. Do you know what the N is for on the transfer case if it's okay with it being in the high position(while the dial is on auto). Sorry if any of that's confusing. I've only had this vehicle since December and I've only had to replace the thermostat on it so far. Just hit 133,000 not too long ago and I'd like to keep her running strong.
 






More detail is provided in the service manual:

"The Borg-Warner 44-05 transfer case is used in the Explorer (4WD) vehicle. The transfer case transfers power from the transmission to the rear axle, and also to the front axle when electronically activated.

Mechanical Operation

In the Auto mode, torque from the transmission is transferred to the input shaft (7017) which, in turn, drives the rear output shaft that drives the rear axle assembly (4006). The 2WD through 4WD auto shift is accomplished through an electromechanical ball ramp clutch assembly.

The electromechanical ball ramp clutch assembly drives the drive sprocket after the GEM activates the clutch coil. The drive sprocket turns the chain which rotates the front output shaft and front driveshaft (4602).

The high-low shift is accomplished when the reduction shift fork moves the reduction collar to lock the planetary gear set to the output shaft. Torque from the input shaft is then transmitted through the sun gear, which then turns the front planetary gear set front planet (7A398). The front planetary gear set front planet which is now engaged provides transfer case speed reduction.

Transfer Case Functions

There are three modes on the transfer case, Auto, 4WD Low, and 4WD High. Neutral is only available as a dealer installed option.

C-Trac Function

The C-Trac transfer case transmits torque to the front wheels through an electromechanical clutch assembly. In the Auto mode, while at rest and under cruising conditions, the Generic Electronic Module (GEM) activates the transfer case clutch at a minimum level. This allows for the slight difference between the front and rear driveshafts which occurs normally when negotiating a corner on dry pavement. Under any of the following conditions, the GEM will increase the torque sent through the clutch to the front wheels in order to prevent or control slip.

- Slip is detected (by monitoring the Hall Effect Sensors in the transfer case)
- Heavy acceleration (by using the throttle position signal from the EEC)
- Very light or zero throttle at speeds above 64 km/h (40 mph) (using the throttle position signal from the EEC)

Range Function

In the 4WD Low Range, the transfer case electromechanical clutch locks the front and rear driveshafts for maximum 4WD traction. The transfer case motor also rotates the shift cam to move the reduction fork to the 4WD low range position. This low range shift is accomplished through a planetary gear set which changes the torque to the driveshaft from 1:1 to 2.48:1 ratio.

In the 4WD High Range, the GEM locks the front and the rear driveshafts for maximum 4WD traction. This position is not meant for use on dry or merely wet pavement. It is intended for off-road or severe winter weather use only. "
 






Thanks much!!!!!!!!!
 






...Do you know what the N is for on the transfer case if it's okay with it being in the high position(while the dial is on auto)...

Yep. Normal.

The N position on the transfer case isn't "for" anything, except for the computer (GEM) to command the electric shift motor on your transfer case to rotate through when shifting ranges from 4HI to 4LO.

Yeah, these things literally do have a Mind of Their Own.

Two, actually: the PCM and the GEM.
 






More from the service manual:

"Transfer Case - Automatic Four Wheel Drive (A4WD)

The A4WD system is 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 modes at any speed. To engage or disengage LOW range, the vehicle speed must be less than 5 km/h, the brake depressed, and the transmission must be in NEUTRAL.

The front/rear driveshaft speed sensors (Hall effect) are mounted to the transfer case and detect the speed of the front and rear driveshafts. This input is used by the generic electronic module (GEM) primarily to control A4WD operation.

The throttle position output signal is provided to the GEM from the powertrain control module (PCM). This signal is used by the GEM in controlling the A4WD clutch.

The shift motor sense plate, an integral part of the electric shift motor, informs the GEM to the position of the transfer case.

The digital TR sensors are located on the LH side of the transmission; these sensors inform the GEM when the transmission is in the neutral position.

The electric shift motor is mounted externally at the rear of the transfer case. It drives a rotary cam which moves the mode fork and range fork within the transfer case between the A4WD, 4HIGH, and LOW range positions.

The 4x4 shift motor uses a module containing two relays which, under the control of the GEM, shifts the transfer case shift motor between A4WD, 4HIGH, and 4LOW modes.

The solid state clutch relay is used to activate the A4WD clutch within the transfer case.

System Function

Hall effect sensor monitors input and output shaft speed.

In the A4WD (C-Trac) system, the GEM varies the torque sent to the front driveline by controlling the transfer case clutch. At rest and under cruising conditions, the GEM activates the transfer case clutch a minimum duty cycle (percentage of time the clutch is turned on), which allows for the slight difference between the front and rear driveshafts which normally occurs when negotiating a corner on dry pavement. Under any of the following conditions, the GEM will increase the duty cycle in order to prevent or control slip:

  • Slip is detected (by using the Hall Effect Sensors)
  • Heavy acceleration.
  • Very light or zero throttle at speeds above 25 km/h (40 mph)
Feature inputs:

  • 4WD mode switch.
  • Digital TR sensor.
  • Vehicle speed signal (transmitted from the ABS module).
  • Front/rear driveshaft speed sensors.
  • Throttle position information from the PCM.
  • Contact plate position inputs A, B, C, D.
Feature outputs:

  • Solid state clutch relay (pulse width modulated signal: grounded when relay is on, battery potential when relay is off).
  • A4WD indicator (ground when activated, open circuit when deactivated).
Shifts between A4WD and 4x4 HIGH can be made at any speed. Listed below are the inputs and outputs needed by the GEM to execute a change between any of these modes.

Feature inputs:

  • 4WD mode switch.
  • Hall effect sensors.
  • Contact plate position inputs A, B, C, D.
Feature outputs:

  • 4x4 shift motor relay outputs.
  • Solid state clutch relay (pulse width modulated signal; grounded when relay is on, battery potential when relay is off).
  • 4x4 HIGH cluster indicator (ground when activated, open circuit when deactivated).
When shifting into or out of LOW range, the GEM requires that the vehicle speed is less than 5 km/h (3 mph), the brake is applied, and the transmission is in NEUTRAL.

Feature inputs:

  • 4WD mode switch.
  • Contact plate position inputs A, B, C, D.
  • Vehicle speed signal (transmitted from ABS module).
  • Brake input (battery voltage when brake is depressed, open circuit when not activated).
  • Digital TR sensor (ground when transmission is in NEUTRAL, open circuit otherwise).
  • Start/clutch depressed input.
Feature outputs:

  • 4x4 shift motor relay outputs.
  • Cluster indicators (ground when activated, open circuit when deactivated).
  • Solid state clutch relay (pulse width modulated signal; grounded when relay is on, battery potential when relay is off)."
 






I figured I might as well post the rest of that here as well so it's all in one place.

Now that we've got that out of the way...
I have no idea what's going on with your vibration issue nor whether or not it may be related.

:dunno:

Link to Joeetogo90's bad vibrations thread.
 






Well what about the blinking 4wd dash lights? Mine just started the same 6 times every couple minutes.
 






Marc I just fixed one of those. Had code P1837 rear output shaft speed sensor fault. I did resistance tests and a live data stream to confirm. Replaced sensor all good now.

So get the codes read and take it from there. Best wishes.
Doc
 






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