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4X4 doesn't work on '91

Discussion in 'Stock 1991 - 1994 Explorers' started by Malchi, August 7, 2010.

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    1. Malchi

      Malchi Active Member

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      City, State:
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      Year and Model:
      '91 X 4x4
      Ok, just bought a 91 Explorer, some of you have been very helpful on fixing the problem with it boiling over when I shut it off, so thought I'd ask another question, but felt like I needed a new thread for it.

      This thing has the push buttons on dash for 4-Lo and 4-Hi, but pushing either of them does nothing. I mean, nothing whatsoever.

      Never having owned a Ford 4X4, where do I start on troubleshooting this problem?
       
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    3. Iron Weasel

      Iron Weasel Active Member

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      City, State:
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      Year and Model:
      1994 XLT 4x4
      There are several possibilities of what the problem could be.

      #1 - Transfer case shift motor is "lost".
      There is a plastic bump stop in the transfer case that keeps the shift motor aligned against the case. It's fairly common for that plastic stop to become brittle and break which causes the shift motor to "forget" what position the transfer case is in. There are many threads on this board that detail the problem, where the stop is, and how to fix it.

      #2 - The Electronic Shift Control Module not working.
      The Electronic Shift Control Module is located over the left rear wheel well on 2 & 4 door models and it makes a telltale "click" when you push the 4x4 button on the dash. You might have to listen carefully for it or have a helper sit in that area. If you hear the click, then the control module and dash switch are working and your problem most likely lies with the motor on the transfer case.

      #3 - Electronic Shift Control switch.
      This is the switch on the dash that houses the 4x4 and Low Range buttons. If the light next to the button and the light on the dash light up, then the switch is probably OK and you need to work back through the Control Module and then the motor. If the lights don't come on, then you could have a bad switch.

      Typically, when the transfer case doesn't engage on the first gen Explorers, it's due to the transfer case motor either not shifting because it's just plain busted or because the bump stop is broken off and the shift motor goes into a "failsafe" mode and won't shift.
       
    4. ernzo

      ernzo Elite Explorer

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      I had this. I listened by the rear driver side - opened the gate and leaned in - and heard the click.

      I then tapped gently on the shift motor - GENTLY - and that loosened it up so it would shift temporarily. Need to replace or R&R. Actually easier than I thought!

      As I recall, the lights do not come on unless the unit actually shifts and that threw me, I expected lights. Everyone does!
       
    5. Malchi

      Malchi Active Member

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      ok, what about the operation of this 4X4? I have had a couple Jeeps and you shifted them into 4WD on the fly, while the vehicle was moving. But, my Toyota 4Runner you had to stop, or nearly stop, it to shift.

      How does this work? If it is sitting in "Park" and I press the buttons, will the Module still click, or does it need to be moving a bit?
       
    6. Iron Weasel

      Iron Weasel Active Member

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      You can shift into 4Hi at pretty much any speed or completely stopped, doesn't really matter. To get into or out of Low Range you have to be stopped, transmission in neutral, and clutch depressed (on a manual trans).

      You should be able to hear the ESCM click over into 4x4 sitting in the driveway with the key on / engine off. Of course, that's if it's actually working.

      Here's how to check the module:

      [​IMG]

      First off, make sure you have power to the module and the module itself has a ground. A test light or DMM along with basic electrical knowledge is helpful.
      If you have good electrical connections, follow the rest of the steps.

      DISCONNECT the B and C connectors , turn ON the ignition and allow 4 seconds for the Module to power up.
      Then PUSH the Diagnostic Test button.
      If the LED doesn't illuminate , the Module is dead and must be replaced.
      If the LED comes on and stays on for 30 seconds , there is an error condition and the module will have to be replaced.
      If the module is OK the LED will flash 4 times.

      The module is above the left rear wheel well. On my 94, you'd have to remove the access panel where the jack is stored and it's towards the front of that compartment - not to hard to get to.
       
      Last edited: August 7, 2010
    7. Malchi

      Malchi Active Member

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      Ok, what a really great forum. Y'all answer quickly and detailed. A big thanks to all.

      Anyhow, I need to make a correction. I stated that when the buttons are depressed nothing happens whatsoever. Well, seems I was wrong. I depressed them while driving down the road, and, since the lights didn't come on I just concluded nothing was happening. Well, since reading the responses to my question I went out there, turned the key on, engine off, and depressed the 4x4 button and I can hear some clicking and, I think, whirring noises. I definitely hear a clicking coming from the ESCM. So, that means it is working at least, no? But, the light is not coming on next to the button. Also, depressing the 4LO button does nothing at all. No clicking or whirring. At least, I didn't hear any. I was diaging alone so had to depress the buttons and run quickly back to the rear and listen for a clicking noise, but heard none.

      Will try to find a helper tomorrow and test for sure and post back my definite results.
       
    8. Iron Weasel

      Iron Weasel Active Member

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      If the control module in the rear is clicking, then the problem most likely lies with the shift motor itself which is bolted to the rear of the transfer case. The light next to the button won't come on until the transfer case is actually in 4Hi. The whirring you hear is probably the shift motor trying to shift the case.

      Take a look at this thread: http://www.explorerforum.com/forums/showthread.php?t=123542

      It gives a lot of detail about the operation, disassembly, cleaning, & reassembly of the motor. I haven't checked through the whole thread, but I think there may also be a "fix" for that bump stop that has a tendency to break.
       
    9. Malchi

      Malchi Active Member

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      Ok, located the control module and tested it. It blinked 4 times and stopped. Means it's fine. So, my problem is obviously in the shift motor. Problem is I don't know when I can find time to remove it and check it out.

      Will post back once I have time to do so.
       
    10. Malchi

      Malchi Active Member

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      Ok, the excitement got to me. I went ahead and did it. Not too bad, really. All I did was remove the shift motor, pulled the gear out, and sure enough, the plastic stop was in pieces. So, I took a bit of vacuum line that fit nicely over the peg and stuck it on there, put everything back together, sealed it all up nicely, and now the lights for switch and dash are coming on just fine. Just need a chance to test it out. Soon as I get the freeze plug replaced....

      Thanks Iron Weasel for all the help.
       
    11. Iron Weasel

      Iron Weasel Active Member

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    12. 94Sport5Sp

      94Sport5Sp Member

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      Hi:

      Just to add one point of clarification. Assuming that you have auto locking hubs then as stated by Iron Weasel "You can shift into 4Hi at pretty much any speed or completely stopped, doesn't really matter.". If you have manual hubs then you must engage the hubs first then shift into or out of 4hi as desired.

      Remember that shifting into 4hi the front axle (which is not moving) needs to move and match the speed of the wheel so you will hear a decided clunk as you engage 4hi with auto hubs. The faster you go the harsher the engagement and therefore the greater the stress on the components.

      Just some additional thoughts
      PaMnd
       
    13. Malchi

      Malchi Active Member

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      Thank you, I appreciate any information I can get. I do have the automatic hubs, and I will be sure to engage at low speeds whenever possible.

      BTW: when I shift out of 4WD, do I need to disengage the hubs somehow, or will it just disengage itself? I used to have an '86 4Runner that had the automatic locking hubs and you had to put it in reverse and back up a few feet to disengage the hubs. Necessary for the Explorer or no?

      Also, how dependable are the automatic locking hubs?
       
    14. Iron Weasel

      Iron Weasel Active Member

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      You should do the same with the Explorer just to make sure that the hubs are unlocked.

      Depends on how well you maintain them and how rough you are on them. People have a tendency to "service" the auto hublocks by packing them full of grease which renders them pretty much useless. I bought our Explorer with the auto hubs on it and when I took them off to replace them with OEM Warn hubs (scored a pair at the junkyard for $30), the hub was full of what looked like wheel bearing grease.

      Anyway, if they're in good condition, not packed full of grease, and you only expect to see light use, then they should be fine. If you're planning on using them for more than snowy roads or light trails, then you should consider manual hubs. Yeah, you'll have to get out and turn the knob, but they're stronger & more reliable than the auto hubs.
       
    15. 94Sport5Sp

      94Sport5Sp Member

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      Hi:

      Therein lies one of the weaknesses of auto hubs. While in 4x4 changing direction will disengage the hubs. The book says 10 to 15 feet but it can happen within inches. This is a problem if you are stuck because you lose 4x4 when you change direction and this can be really hard on the hubs. With manuals you are engaged until you turn the knob so you never lose 4x4 and changing direction will not stress the hubs.

      Convenience versus function
      PaMnd
       
      Last edited: August 15, 2010
    16. Tony H

      Tony H Well-Known Member

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      The Auto Hubs on these Explorers are very bad/weak/ not dependable.
      Do a Search on Auto Hubs and you will get an arms length of complaints.
      There is a lot of chessey plastic in these hubs that warp and distort.
      If you get a few bucks... put the Manuals on.
      Mile Marker or Warn sells tem for the First Gen Explorers
      I hate the Auto hubs since they all have to disengage and reengage when you change direction. If you need to Rock your vehicle out of a hole with Auto Hubs.... you are done.

      Here's some info.....http://www.explorerforum.com/forums/showthread.php?t=232754
       
    17. Iron Weasel

      Iron Weasel Active Member

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      Warn made manual hubs that were OEM on some Explorers and Rangers in the 91 - 94 years as well. I'm pretty sure this was an additional option that not many people took. They're essentially the same hubs as what you'd buy from Warn now and if you can find a junked Explorer or Ranger with the manual hubs, you can save yourself gobs of cash.

      I actually happened to come across a 94 Ranger in the local U-Pull-It yard about 6 months ago when I was there looking for something for an entirely different vehicle. The truck had only been on the lot for 2 days according to the sticker, so everything was pretty much intact. I verified that the hubs worked then pulled them off and they were in almost pristine condition inside.

      Total cost for 2 Warn manual hubs?

      $20.

      :D
       
    18. cmhaah06

      cmhaah06 Active Member

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      Ok, I am having the same problem right now with my 4x4. I too have the push button transfer case. I read the thread in the link and I am going to repair the motor. When I push the 4hi button I hear clicking going on at the module, and I can see the needle in the electrical gauge moving, so my conclusion is that the bushing is crushed. What size rubber hose is being used to replace the bushing if that is the problem?
       
    19. Malchi

      Malchi Active Member

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      I used a piece of standard 1/4" vacuum line. Just pushed the end over the little peg that held the bushing, then cut it off flush with the top of the peg. Worked great.
       
    20. Malchi

      Malchi Active Member

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      Can someone tell me how important the counter weight on the back of the transfer case is? I took it off to fix the motor, and haven't gotten around to putting it back on yet. I plan to do it today, but........

      What is it for?
       
    21. edhowell

      edhowell New Member

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      Ok I have done these test and the module passed them. I will get under it tomorrow and remove the motor and check it.

      But I have a question. My lights keep coming on and going out when I start it. Sometimes it will show 4WD only sometimes it will say lo range also. Sometimes nothing. I know the transfer case is in 4WD and will not come out but sometimes the lights go out.

      My question is is this most likely because the plastic bushing is screwed and the motor is lost as to what position it is actually in?
       

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