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4x4 Troubleshooting guide

Discussion in 'Stock 1991 - 1994 Explorers' started by DeRocha, December 16, 2007.

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    1. DeRocha

      DeRocha NEX Vice President Elite Explorer Moderator Emeritus

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      4x4 not working (91-94)

      The purpose of this thread is to consolidate troubleshooting information in one area so people can find the correct information quickly. It is not intended to become a huge run on thread where people ask questions as this would defeat it's purpose. Questions should be asked in other threads and any additional information deemed appropriate will be added to this one.

      Interactive How Cars work Animation. Click on Drivetrain and you can see the various steps to go from 2WD to 4WD (Note step 5 is incorrect for Ford Automatic hubs, To unlock Ford Autohubs you must reverse direction for several feet).

      4x4 High
      The 4x4 system can be shifted on the fly into 4x4 high at anytime. If pressing 4x4 fails to activate 4x4 (The dash and button 4x4 lights are off) then you have a failure in the system (Dash button, 4x4 module, Shift motor). If you listen carefully you should be able to hear the relays in the 4x4 module when you press the 4x4 button. If you cannot hear the relays recruit a friend to sit near the module and listen. If the relays make noise it indicates the 4x4 module has received input from the dash button and the problem lies in either the 4x4 computer or the shift motor.

      If you cannot hear the 4x4 relays then you will need to verify the 4x4 module is working.

      The most common problem is a broken Stop Bumper within the Shift Motor. The worm drive on the electric shift motor puts out a LOT of Torq. As such when returning to the 2H position the shift motor doesn't stop on a dime and needs the Stop Bushing to Prevent:
      • The Geared Position Sensor from traveling outside of it's operational range. When this occurs the 4x4 module becomes lost, and will no longer shift the T-Case as it cannot determine the position of the T-case selector shaft.
      • The Geared Position Sensor from getting JAMMED against the metal stop. Once it gets jammed against the 2H Metal stop the shift motor may not have the power to Un-Jam itself when you push 4x4.
      See the Shift Motor rebuild thread on how to fix the Shift Motor.

      To re-sync the shift motor:
      1. Mark the Geared Sensor cover to case
      2. Remove the Shift Motor from the T-Case
      3. Remove the Geared Sensor Cover
      4. Remove the Geared Sensor
      5. Turn the T-case selector shaft to 4H
      6. Re-install the Shift Motor case (no bolts)
      7. Re-install the geared sensor
      8. Turn the shift motor case so it's bolts holes align with the T-Case (install bolts)
      9. Ensure Geared Sensor is seated into housing (never force with cover)
      10. Re-install the Geared Sensor cover
      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.

      Notes: If the Selector shaft was in 2H (default position) it could get jammed against the stop making it difficult to align and install the Shift motor mounting bolts. Placing the Selector shaft in between 2H and 4H gives you a 1/2"+ of play forward or back when installing the case allowing you to easily align and install the shift motor bolts.

      If the Geared Sensor isn't seated all the way you can gently tap it in with a rubber/plastic mallet. Never try forcing it down with the cover as you'll damage its electrical contacts.

      Checking the 4x4 module (rear trunk).
      Unplug the two connectors that plug directly into the module (left side), turn the key on and push the reset/test button on the module. The LED should flash four or five times and stop. If the LED flashed the four or five times, the module believes it is ok internally, and you'll need to check the external parts like the 4X4 switch, shift motor, magnetic clutch and wiring harness. If the LED did not flash at all or kept flashing continually, the module is telling you that it is damaged internally. (check for power & ground).

      Click a thumbnail for full size image
      [​IMG] [​IMG] [​IMG]

      Its fairly common on 1st Gen explorers to periodically have a dimly lit LEDs next to the 4x4 buttons. Mine tend to appear dimly lit a few times per month, more often when it gets cold out. Rest assured you vehicle is not in 4x4 unless both the dash and button lights come on.

      4x4 High
      To engage or disengage 4x4 High:
      • Press the 4x4 button (anytime, nothing else required!)

      4x4 Low
      To engage or disengage 4x4 Low you must:
      • 1st be in 4x4 high
      • Transmission in Neutral
      • Clutch depressed (manual transmission)
      • Foot on Brake (mph<3)
      • Now Press 4x4 Low

      HUBS
      Hubs (automatic & manual) are used to lock the front wheels to the axles allowing the wheels to be powered. Locking is a purely mechanical action and is insensitive to the electronic 4x4 system. For manual hubs the locking occurs when the hubs are turned to the "Lock" position. For automatic HUBs the locking occurs when the axle shaft begins rotating within the HUB, which causes the splined engagement mechanism to idle up on the engagement cam which locks the hub in the current direction.

      Any clicking or ratcheting noise from the front wheels) is a sign the automatic hubs are not locking.. An Easy test is to get under your truck and rotate the front axle shafts (not the drive shaft).. Rotating the axle shafts by hand mimics 4x4 being engaged. After a few revolutions an Autohub should lock in and be impossible to turn.. If you are able to keep turning the axle it indicates the hub is bad/gunked up. For manual hubs the test would be to get under the truck with the HUB unlocked (4x4 off) and verify the axle shaft rotates freely. Next lock the hub, the axle shaft should be impossible to turn. If you are able to turn the axle it indicates the hub is bad/gunked up.

      Worn or heavily greased autohubs tend to buzz or chatter when going around corners (the hub mechanism is partially trying to engage). If you lock the hubs and the noise goes away then a good hub cleaning is in order.

      HUBs (automatic & manual) are insensitive to the electronic 4x4 system. The electronic 4x4 system only shifts the T-case in/out of 4x4 by means of an electric shift motor and 4x4 computer. The computer is used to determine the current position of the T-case selector shaft which will determine the course of action when the 4x4 Buttons are pressed.

      To clean see the repair info in my sig line or find threads like:
      Fixing/cleaning my automatic hub

      If the T-case is engaging (lights indicate 4x4), but the front end doesn't feel like its locked then one or more hubs are most likely blown.

      The easiest way to test hubs while the vehicle is still on the ground:

      To test for a blown Auto Hub;
      1) Put T-case in 4x2 (disengage 4x4)
      2) Crawl under the truck and rotate the axle shaft (any direction). After several revolutions the autohub should click and lock. If you can still rotate the axle shaft the hub is blown..
      3) Repeat #2 on the opposite axle shaft..

      2nd test for blown Auto hub
      1) Put T-Case in 4x4 (engage 4x4 for 20' while going forward to give autohubs a chance to lock)
      2) Put Transmission in park
      3) Jack up the Left (driver's side) front tire and try and rotate the whole wheel (Counter clockwise).
      5) Jack up the Right (passenger side) and try and rotate the whole wheel (Clockwise).
      4) If you can move either wheel it indicates the autohub Failed to lock and is bad.
      *Do not reverse direction in this test as an autohub could be unlocked. Also pay attention to the direction of the rotation (if you rotate the wheel the wrong direction it will unlock and invalidate the test.

      To test for a blown manual Hub;
      1) Put T-case in 4x2 (disengage 4x4)
      2) Lock in the Hubs
      2) Crawl under the truck and try and rotate the axle shaft (any direction). If you can rotate the shaft the hub is blown..
      3) Repeat #2 on the opposite axle shaft..

      More on Automatic HUB engagement:
      When you engage 4x4 the front drive shaft will spin and send power to the diff and then to the axle shafts.. The axle shafts will begin rotating within each autohub; after a few revolutions the engagement cam will have idle up within the autohub and caused the autohub to lock. Once this occurs on both hubs the wheel with the least traction will get power and begin to rotate.

      :scratch: Let the above sink in for a minute.. If you try to free a vehicle by quickly going from Forward to reverse you can easily blow an auto hub.. When you reverse direction the axle shaft obviously spins in the opposite direction causing the auto hub to UNLOCK and then LOCK in the new direction.. Under low power this isn't a big deal, but if you're on the gas heavy it can definitely damage the hub... Manual hubs are either locked or open, as such they are unaffected by rocking a vehicle in the manor above.
       
      Last edited: April 1, 2013
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    3. kustom77

      kustom77 New Member

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      thanks for the help troubleshooting my 4 wheel drive.
       
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    4. Tbars4

      Tbars4 Offroad/Fitness Moderator Staff Member Moderator Elite Explorer

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      ...great thread....:thumbsup:
       
    5. Rattosh51

      Rattosh51 New Member

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      Make it a "sticky"...very good info and some of the most asked questions answered in one article. Thanks DeRocha!!!:thumbsup:
       
    6. MrShorty

      MrShorty Explorer Addict

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      I second the "sticky" nomination.
       
    7. bkkbb1

      bkkbb1 New Member

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      Hello, just recently signed up, though been reading the posts for awhile. I did the hinge pin
      replacement this weekend, now my door closes perfectly. Thanks DeRocha. Now I am focusing on the 4x4 problem and had some questions. How hard is it to shift the t-case manually? Should there be a lot of resistance or can you almost turn it by hand.
       
    8. DeRocha

      DeRocha NEX Vice President Elite Explorer Moderator Emeritus

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      You will need to use an adjustable wrench or long pliers as it will take some force (regular pliers were too small for me to use) to initially get the shaft moving. Once it moves it will click into each setting. To move into/out off 4L you will need to have the transmission in neutral.
       
    9. bkkbb1

      bkkbb1 New Member

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      I had the shift motor off a couple of weekends ago to check the stop on the gear, which was gone, and wanted to see how hard it would be to turn the shaft. I used a set of channel locks and it seemed to turn very easily, and I did hear a click when turned to 4h. It turned easily back again.

      When I bought the truck I was told that the 4wd wasn't working. So I pushed the button... and it went into 4h. Stayed there to. Then my father-in-law took it to the dealership... Without asking. Almost $700 just to get it out, and didn't fix the problem. They put a used shift motor on it to get it out. That was the one with the busted stop.

      I have another with the busted stop problem and will rebuild it. Then swap. Thanks for the reply DeRocha. I will have another question when I have more time.
       
    10. myslyn

      myslyn New Member

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      Yeah, this is some GREAT information and I'll need to reference when we start addressing our 4x4 issues on our '93 explorer. It stopped working when we came back from FL in '04 and it really sucked 'cause we needed it as soon as we got back! :)

      We made it though and I'm glad to finally also learn that the 4x4 is controlled by the transfer case under the truck. When we mentioned it was not working a couple times to other mechanics, they never corrected me when I said that I thought that the mechanic in FL cut the line to the 4x4...

      anyway, great post!
       
    11. BrooklynBay

      BrooklynBay Staff Member Moderator Elite Explorer

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    12. Mazda87

      Mazda87 New Member

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      Hey this has some great information! I just bought a Navajo a couple of weeks ago and the 4x4 is not working, after reading this I am almost positive that it is the shift motor. But let me explain the situation just to make sure. When I first bought the Mazda the 4x4 buttons didn't light up. I bought a new switch and now the light up, however when I push the button nothing happens no light on the dash indicating that the 4x4 is on nor the little light by the button. When I do bush the button I do hear a kind of clicking noise, is that the relay? It doesn't sound like it is coming from the tires so I don't think that it can be the hubs.

      Now my next question if it is the shift motor, I don't think I can handle the rebuild I am not very good at cars, now give me some plywood and I can make you a cabinet, unfortunately my woodworking skills don't transfer to automotive. Now back on topic, I see shift motors for 80 bucks on ebay. Are these reliable, has anyone tried them?

      Thanks for all the help, I am going to go to the other sticky thread for the door hinge now...
       
    13. gsmaclean

      gsmaclean Active Member

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    14. JohnnyRook

      JohnnyRook New Member

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      4x4 problems. Auto Hubs?

      My 4x4 is not engaging. I can hear the computor clicking in the rear when i puch the 4x4 button, and the light comes on. I can also hear the shift motor engage the front drive shaft. This being the case I am assuming that the problem lies my auto hubs.

      I just wanted to make sure I do the right thing to check this theory. I need to put the car in 2 wheel drive and try to rotate front axel? If the truck is in 2 wheel drive wouldn't the hubs be unlocked?

      I'm going to clean out my hubs tomorrow so I was also wondering if there are any ways to tell if the 4x4 is engaging (i.e. do the hubs make a noise when they lock in? or can you feel a difference when driving?)

      Thanks everyone!!!
       
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    15. DeRocha

      DeRocha NEX Vice President Elite Explorer Moderator Emeritus

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      If your vehicle is in 2H the Automatic HUBs should be unlocked (unless you haven't reversed direction since the last time 4x4 was engaged). The Automatic hub test in the 1st post will verify the hubs are locking by you manually locking them by rotating the front axle shafts.

      As an example of how hubs work..
      In a normal working vehicle if your engage 4x4 the front drive shaft will power the front axle shafts. The axle shaft rotating within the automatic hub will cause the inner hub mechanism to move inward against the cam and lock up. If you were to disengage 4x4 the T-case would be disconnected from the front drive shaft, but the front drive and axle shafts would still rotate since the shafts are still locked to the wheels via the HUBS. If you were to reverse direction the axle shafts would cause the the inner hub mechanism to move outward against the cam and cause it to unlock.

      Note: If you were to reverse direction (while 4x4 is engaged), the hubs would unlock, then re-lock in the opposite direction. For this reason it is never good to free a stuck vehicle by quickly shifting from forward to reverse.
       
    16. kore94

      kore94 New Member

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      I have a 94 ranger Ext. that has a problem w/ the 4x4. It would engage when it wanted to, & at times not. The lights in dash would light up intermitenly when in 2wd. I repllaced the transmission shifts linkage cable last week which has nothing to do w/ this but then also changed the 4x4 worm drive shift motor. I attempted to use 4x4 to no avail, I had a buddy OHM out the switch in dash and it passsed the parameters. Has anyone had this problem. I also disconnected the to 8 and 5 pin harnesses on the transfercase control module and pushed test button. It worked once blinking about 3 times but when I attempted to show buddy, it did nothing. please help
       
    17. DeRocha

      DeRocha NEX Vice President Elite Explorer Moderator Emeritus

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      If you check the 4x4 computer as outlined in post #1 and below and it didn't flash you will need to verify the unit is correctly grounded and is receiving power. It could be simply a loose wire (ground or power) which is causing intermittent operation.

       
    18. kore94

      kore94 New Member

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      pwr and grounds are good to the module and relays are all working.. when i plugged everything back in and engaged 4hi system worked properly. as soon as i pushed 4lo it temp. engaged and all lights started to flash then all lights went out and now have a system that is not working again...
       
    19. kore94

      kore94 New Member

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      4x4 engaged perfectly, but now Truck is stuck in 4Lo as stated above and lights no longer work. Re-tested module and no blinks, no clicking, no lights in dash, fuses good. I will continue to find this gremlin in system and write in later as this may help other members, thanks for the help.
       
    20. kore94

      kore94 New Member

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      The gremlin within system ended up being a faulty transfer case control module, as it would work intermitenly, and this was the cause for the dash lights to come on in a pulsing sequence while in 2wd. This is somewhat a rare accurance according to a tech I know as the motor then switch typically give out w/ time. repeated testing of the module w/ 5 and 8 pin unclipped harnesses confirmed this as 4-5 self-test flash sequence didn't always accur. I'd like to take the time to thank this site and DeRocha for the detailed help.....tread lightly, kore94
       
    21. pokodan

      pokodan New Member

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      4x4 switch wiring connector

      this is excellent for helping me fix my 4wd BUT my problem now is that the wires to the dash switch are all disconnected and i cant find any electrical diagram for the switc itself and their position in the connector. can anyone take a picture of this area and proper color coordination?again this thread is invaluable up to my point.92 exploder sport
       
    22. dpacman

      dpacman New Member

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      wiring diagram needed for 4x4 control module

      I have a 1992 ford explorer sport 4wd with a 5 speed.
      and as seems so common the 4wd low does not work, i have checked everything listed in thse forums and then some, yes its in neutral, not moving, brake depressed, allready in 4wd hi, the 4x4 control module passed the self test, the actuator works and puts the tansfer case into and out of 4x4 hi ( i am assuming this wouldnt happen if the cam posistion sensor and or bump stop inside of it wasnt working) also checked the 4x4 low switch and wiring harness all the way from the switch to the module with an ohm meter, took the control module apart and verified the i was getting power, ground, contact with connectors was good and relays were working, they do when i put it in hi but nothing happens when pushing the 4x4 low button although i can verify the circuit is being closed from button one the dash all the way to the circuit traces on the control module.

      at this point id like to find a diagram of the pin outs on the control module so i can start tracing the circuity to the safety switches but cant find it one anywhere. any help would be greatly appreciated.
       
    23. Tbars4

      Tbars4 Offroad/Fitness Moderator Staff Member Moderator Elite Explorer

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    24. pokodan

      pokodan New Member

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      4x4 low not working

      do take apart your motor cause it aint a big deal and follow the thread above and put a new piece of rubber in place of your almost guaranteed broken plastic bumper stop and trim it to fit at the top of the stopper and hook it back up and it should work like a charm.p.s. instead of cutting the brown wire just undo the clip holder and dont lose it and put it back when your done. it aint hard.mine was the same -no low then no nothing-now it charges the dunes again.if only i had the money for stronger suspensionhmmmmmmmm.good luck
       
    25. MooseCat

      MooseCat New Member

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      Turning 4x4 switch manually

      I took off the shift motor today and turned the 4x4 switch knob on the transfer case manually. It turned relatively easily and my truck's 4x4 worked great. I've already rebuilt the shift motor following the instructions from:
      http://www.explorerforum.com/forums/showthread.php?t=123542

      Obviously I did it wrong. Any advice on what I should do?

      MooseCat
       
    26. SevyDuce

      SevyDuce New Member

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      Can the gear housing cover be removed to access the stop bumper without removing the entire switch motor?
       
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