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Ron, ASE Certified Technician
Category: Transmissions
Satisfied Customers: 36078
Experience:  35 years working on Ford, Lincolns and Mercs.
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I have a 2005 Tahoe Z71 4wd and continue to have the Service

Customer Question

Customer: ***** *****. I have a 2005 Tahoe Z71 4wd and continue to have the Service 4WD light come on. I have replaced the 4WD module under the dash, transfer case, front diff Actuator as well. I have Codes C0306, C0321, C0327 and B0790. Haven't replaced the position sensor in the Encoder motor yet. Tired of chasing this. Any ideas?
JA: Thanks. Can you give me any more details about your issue?
Customer: In the past when I would be driving highway speed I would look at the selector buttons on the dash and the Auto 4WD light would be on and I never pushed that button.
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Customer: Can you check for me I think I pay monthly for JustAnswer because I have used it before a few times and I believe it is still charged to my AMEX card.
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Submitted: 1 year ago.
Category: Transmissions
Expert:  Ron replied 1 year ago.

Hello, my name is ***** ***** I am a professional here at Just Answer. I have noticed that your question was not getting a response and thought I would see if you still need help with this.I apologize for the delay and I hope I can still assist you with this here.

The codes C0306 ans well as C0321 and C0327 can be set due to any of the following,

  • Transfer Case Encoder Motor
  • Transfer Case Encoder Motor Wiring
  • Transfer Case Encoder Switch

    With the Encoder Motor being the most common cause. In order to determine if that is in fact case you are going to need to do some testing. I have enclosed the steps in the link below. Copy and paste the link to your browser to open and view them.