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1999 ( 2000 Model ) Service 4WD Error Help?

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Hello everyone, I have an issue this morning with my z71. I loaded my truck down with house hold garbage.. Turned on the truck no issue that I noticed ( Havent started the truck in a week) Got in to drive then noticed all the lights on the 4wd selector on the dash were lit and the service 4wd was reporting on the dash console. I unhocked the battery for 5 mins and tested again, same issues. Hooked up tester ODB2 no errors. Can anyone help me with this? Any advice?


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I had the exact same issue on my 2004 z71. Random shifting into 4wd, sometimes would not shift out etc. "Service 4wd" was constantly showing up and after replacing the switch itself that did not solve the problem. If it is not your switch its most likely your encoder motor sensor, a factory sensor is around $50 on Amazon. Since replacing mine I have had 0 issues. 




This is a link showing detailed instructions on how to replace the sensor. Pretty simple yet tedious job. 

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Yes they did! or sometimes they wouldn't come on at all. It was an intermittent problem but very frustrating. The encoder motor sensor is most likely the culprit. Let me know if you have anymore questions would be glad to help. 

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If this issues happens the lights will stay on the whole time, took it to Chevrolet Dealership, found out it was the Transfer Case Control Module that is located inside the dash, it costed me $511 from the dealer. I had them install it and the total was just under 1k. But its now fixed. Hope this helps someone out who is having this same issue.

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