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Help please...

Discussion in 'Chevy Trucks' started by Pinzgauer, Jan 22, 2016.

  1. Pinzgauer

    Pinzgauer Senior Member
    from Vermont
    Messages: 134

    Of all times today my truck won't go into 4x any longer.
    Turning the knob won't blink the light or engage the motor for the TC pin or fork.
    No power to that motor.
    DIC says "Service 4 Wheel drive".
    Is there a fuse I might be missing?

    2007 LMM GMC SIERRA 2500HD Duramax

    Thank you..
     
  2. dieselss

    dieselss PlowSite Fanatic
    Messages: 10,977

    Might be the motor itself. Remove it and then turn on the 4x4 see if it moves. Also while it's off you can then engage the 4x4 by turning the little shaft.
     
  3. Pinzgauer

    Pinzgauer Senior Member
    from Vermont
    Messages: 134

    Thank you.
    Is there a way to engage the shaft by hand permanent.. For the time being to get through the next two days?
     
  4. dmcenery

    dmcenery Member
    Messages: 53

    I would turn the truck off and try turning the dial again to see if that helps. Most likely it's the actuator that goes into the front diff not engaging. I think that's like a $70 part at the auto parts store. Otherwise it could be the transfer case encoder motor that's bad. That's on the side of the trade $200 + for that. GM scanner will tell you for sure.
     
  5. dieselss

    dieselss PlowSite Fanatic
    Messages: 10,977

    Yes, turn that stub shaft with a pair of pliers. Should be one click? I think.

    Ah yes the front actuator forgot about that.
    That could be it. Like was said try turning truck.off, then turn the dial then start the truck.
     
    Last edited: Jan 22, 2016
  6. Mr.Markus

    Mr.Markus PlowSite Fanatic
    Messages: 5,170

    Yes, sometimes turning the truck off and turning the dial to 4x4 and restarting will work. I had the same problem it turned out I needed a new dial switch, have you noticed it gets quite warm?
     
  7. rjigto4oje

    rjigto4oje PlowSite.com Addict
    Messages: 1,296

    Ok im just throwing this out there. I read somewhere there is a way to override the front accuator by using a pice of pipe like connector hopefully someone else will chime in
     
  8. rjigto4oje

    rjigto4oje PlowSite.com Addict
    Messages: 1,296

    Well keep lookjnng op
     
  9. dmcenery

    dmcenery Member
    Messages: 53

    Mr. Markus,

    If it's a new body style 2007 with the knob yes the knob does get warm. Old body style 2007 has the push buttons which don't get hot. I have had problems with both. T case is different manufacturer between OBS & NBS 2007 trucks.
     
  10. absolutely

    absolutely Senior Member
    Messages: 237

    2000 lbs in the bed will help you get through the storm as a last ditch effort. I have done it
     
  11. Pinzgauer

    Pinzgauer Senior Member
    from Vermont
    Messages: 134

    Thanks for all the replies.
    I just want to understand how to manually engage the shaft into the front TC.
    I take off the motor which exposes the shaft that drives the actuator? I turn the shaft with pliers? That will engage the actuator permanently as long as I keep the motor off or can the motor go back on.
    Not sure if I use all the right terminology, so my apologies.

    Also, the motor has a rectangular multi pin plug. Six pin I believe. Which pin and what voltage should activate the motor if I want to try to power it directly to test.
    Thank you again for all the help....
     
  12. Pinzgauer

    Pinzgauer Senior Member
    from Vermont
    Messages: 134

    Never mind the electrical... Found it on all data. Thanks
     
  13. Pinzgauer

    Pinzgauer Senior Member
    from Vermont
    Messages: 134

    OK, so I am posting this in case someone else has the same trouble some day.
    Here is what I wound up doing:
    I pulled the pin designation for the actuator motor from alldata.com
    Took the motor off the TC to check it on the bench. After verifying that it worked and the correct position for ground and hot to make sure that the motor spins the right direction I installed the motor again.
    With jumper leads I used my starter pack to spin the motor.
    Tricky part was to get the actuator just far enough to keep the drive in HI 4X4.
    Trial and error on the lift did it.

    Been plowing in 4x4 all afternoon without any problems.

    Thank you...
     
  14. rjigto4oje

    rjigto4oje PlowSite.com Addict
    Messages: 1,296

    Glad to hear.b safe out there
     
  15. Mr.Markus

    Mr.Markus PlowSite Fanatic
    Messages: 5,170

    So its fixed? Or you engaged 4x4 full time...?
     
  16. Pinzgauer

    Pinzgauer Senior Member
    from Vermont
    Messages: 134

    Not fixed. 4x full time. But it got me through the night.
     
  17. Philbilly2

    Philbilly2 2000 Club Member
    Messages: 2,633

    Sounds like you are down to the switch or the wiring between switch and actuator then.

    Good look, post your findings! Thumbs Up