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The encoder is the portion of the shift motor assembly that senses the current position or mode of the transfer case. It communicates this info back to the TCCM. If you're experiencing the shift motor continually cycling, it's most likely because it doesn't know what position the transfer case is in or it thinks it's in between modes (ie. Between 2Hi and 4Hi). When this occurs, the TCCM starts actuating the motor in one direction or another, trying to establish a known position. If it isn't able to achieve this, it will continue cycling indefinitely. This could either be the result of a wiring issue on the encoder circuits, or a mechanical issue inside the transfer case that's not allowing it to complete a shift.
I've attached a copy of the transfer case system wiring diagram for your reference. Also, have you tried removing the shift motor and attempt to manually shift the t-case with a pair of vice grips on the selector shaft? If you can't shift it manually, there's a good chance something was assembled incorrectly in the t-case when it was rebuilt.
On the diagram, the TCCM is located on the left side of the page. The encoder is at the bottom and the shift motor itself is on the right side in the middle.
Let us know what you find!
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Sunday, September 22nd, 2019 AT 10:22 AM