NP243 transfer case motor pooped? Violent wife....

Discussion in 'Transfer Cases' started by DieselDetroit, Dec 11, 2016.

  1. 884x4310ci

    884x4310ci Newbie

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    Yeah I mean the switch in the dash.
     
  2. 1995sierra305

    1995sierra305 Newbie

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    Would throw a dash switch in it, being cheaper. If not fixed move to the tcase motor.
    But I've also seen similar situations, pulled the drain plug on the case and nothing but a few drips, and chunks of metal. Hopefully thats not yours!
     
  3. DieselDetroit

    DieselDetroit I'm Awesome

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    So I got it to shift into 4 hi and 4 lo by hitting the transfer case shifter motor with a rubber mallet.

    It then got stuck in neutral????? And then back to 4 lo so I had to beat on it a bit more. It then eventually got back into 2 hi and I just left it there

    Does this sound like a bad motor? I'm 90% sure as it makes sense. I removed it and am driving the truck like that for now just to be able to swap the replacement easily. Thanks
     
  4. Bob L

    Bob L Supporting Member

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    So sad that we have become such a push button world. I only had a problem with a hand lever 4 wheel drive once and lubricant fixed it. Same with heat controls ,a cable operated heater was good for 40 years and easy to fix.
     
  5. mistaake

    mistaake Real Name: Michael

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    While I'm inclined to agree with you, just realize how much nicer it looks. You don't have this big ugly lever on the floor. On the other hand, my push-button 4x4 doesn't work either (similar to OP's problem) so maybe you have a point.
     
  6. Biggershaft96

    Biggershaft96 king of the trailer park

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    i would try to find one from a junkyard to test. If it works with a junkyard motor you can either get a brand new one or keep the junkyard one. Sounds to me like youve found the problem though.
     
  7. DieselDetroit

    DieselDetroit I'm Awesome

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    Do you guys know how to bench test one to confirm if it's working?

    There are so many pins I'd like to know where to apply 12v. This would make troubleshooting the existing one and the junkyard replacement much easier

    I can't find any literature on the np243
     
  8. DieselDetroit

    DieselDetroit I'm Awesome

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    Ok guys so the two pin plug is for the motor portion. I applied 12v and reversed polarity for -12v and both times the transfer case motor did indeed move

    The issue appears to be within the transfer case itself..... will check the fluid for starters.

    I took everything apart and re sealed it after opening it up. Will follow up tomorrow.

    Any ideas on what would prevent the transfer case from engaging? Hopefully adding fluid solves the issue :(
     
  9. DieselDetroit

    DieselDetroit I'm Awesome

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    Transfer case needs some big Allen bolts to be opened :/. The seal and the bottom bolt looks dry so I don't suspect it is leaking.

    I plugged the shifter motor and it did indeed move between 2hi and 4hi and 4lo without issues when just standing alone. After I confirmed it was functional I had a little bit of trouble lining it back up to the transfer case so I had to get the wife to shift between 2hi and 4hi while I attempted to bang it in place.

    It's back in now.... next step I guess is the transfer case
     
    BigMike636 likes this.
  10. DieselDetroit

    DieselDetroit I'm Awesome

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    By the way this is the vehicle info and how to remove it in case anyone is wondering

    1997 2DR Tahoe vortec 5700, 4L60E and NP243 transfer case

    Tools: torx 45 bit, 15mm, and 10mm

    1) remove 4 skid plate bolts with a t45 on the bottom and a 15mm atop the skid plate

    2) unplug the motor (2 pin) and position sensor (6 pin)

    3) remove 3 10mm bolts holding the transfer case shifter motor in place. One of the bolts is between the driveshaft and the transfer case so I used a wrench. It was a pain in the ass but doable without removing the driveshaft, you just need to rotate the driveshaft back and forth a bit

    4) the fun part, removing the shifter motor is not fun as clearance is tight but it is doable. I went up first and then slid it towards the front of the vehicle, then back down to get it out

    After it was out, the black plastic cylinder houses the DC motor and has a 2 pin connecter. You can apply 12v and -12v safely and listen/review it for movement. The second 6pin plug tells the TCCM what position the transfer case is in and sends signals elsewhere (I believe?) so I didn't touch that end of it.

    There are several other smaller torx bits keeping the shifter motor together and I took everything apart and inspected it. The gears had minimal metal shavings on them. Check to make sure there is no tranny fluid or water inside any of the components and add grease to the gears if needed. There are also several o ring seals that should be cleaned and replaced if needed. I cleaned the mating surface with a razor blade and reapplied rtv to ensure its sealed tight. Smell the DC motor as burned electronics have a very rancid smell and let you know when they have failed, also visually observe.

    Two of the fasteners were security torx bits which require the end of the torx bit to have a circular depression them. I luckily had a set but vice grips would work too.

    Put everything back together and the wife was able to shift into 4hi without any hammering, and we left it at that.... we will try going back and forth tomorrow.

    Hope this helps
     

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