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Tim's Auto Repair
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I HAVE A 2005 SILVERADO IN MY SHOP WITH A CO327 TRANSFER CASE

Resolved Question:

I HAVE A 2005 SILVERADO IN MY SHOP WITH A CO327 TRANSFER CASE CODE. IT'S AN INTERMITTENT FAILURE. WHAT'S THE BEST WAY TO PROCEED TO DIAGNOSE THE PROBLEM. WOULD THE ENCODER MOTOR OR JUST THE SWITCH BE THE MOST LIKELY REASON FOR FAILURE.
THANK YOU SCOTT
Submitted: 7 years ago.
Category: Chevy
Expert:  Tim's Auto Repair replied 7 years ago.

hi

i would think this is a bad acuator[encoder motor]

thanks

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DTC C0327



Test 1-11



Test 12-21

Circuit Description
The transfer case encoder is a switch that converts a shaft position, representing a mode or range position, into electrical signals for use by the transfer case shift control module. The encoder houses 4 hall effect sensors that are used for channels P, A, B, and C. These sensors provide a path to ground, when a magnet, (part of the Motor Encoder), passes over them.
The transfer case shift control module supplies an 8 V reference and a ground circuit for the encoder Hall effect sensors to function.
The transfer case shift control module supplies current limited 5 V on all the channels, thus as these channels are pulled to ground, the module can interpret the location of the transfer case shift position.
This DTC detects an open, short to ground, or a short to voltage (12 V) in the Encoder Feed Circuit, an open in the Signal Ground Circuit, an open, short to ground, or short to voltage (12 V) in the Encoder channel circuits.

Conditions for Setting the DTC
The transfer case shift control module reads back all high or low voltage on the Encoder channel circuits.

Action Taken When the DTC Sets

 

  • All motor activity will stop and the Transfer Case Lock engaged.
  • A default rail to rail shift may be allowed, (toggle between 4H and 2H).
  • The SERVICE indicator (4WD/AWD) lamp will be latched on for the remainder of the current ignition cycle.

Conditions for Clearing the DTC

  • The transfer case shift control module will clear the DTC if the condition for setting the DTC no longer exists.
  • A history DTC will clear after 100 consecutive ignition cycles without a fault present.
  • History DTCs can be cleared using a scan tool.

Test Description
The number(s) below refer to the step number(s) on the diagnostic table.

  1. Tests whether DTC C0327 sets immediately after start-up, indicating the transfer case shift control module is unable to complete its internal self-check due to encoder circuit malfunction. This step is used to bypass some of the scan tool functionality because all shifts would be prohibited once this DTC is set.
  2. Uses the scan tool to determine it the transfer case shift control module can sense feedback on any of the encoder channels when a shift is attempted and whether the encoder channels change.
  3. Once you have determined if the any of the encoder channels change when the transfer case shifts, this step determines if all the of the encoder channels change.
  4. A sector shaft bound between ranges and unable to be moved by the encoder motor could show an invalid gear position setting this DTC. This step tests if the sector shaft is bound up.
  5. Tests the inoperative encoder channel(s) for proper voltage.
  6. Tests the inoperative encoder channel(s) for proper operation by bypassing the encoder sensor.
  7. Tests the inoperative encoder channel(s) for an open, short to ground or a short to voltage.
  8. Tests the Encoder Feed circuit for proper voltage and that the Encoder Signal Ground circuit has a good ground.
  9. Tests the Encoder Feed circuit for an open or a short to ground.
  10. Tests the Encoder Signal Ground circuit for an open.
  11. There are certain circumstances in which an encoder failure will set DTC C0237 immediately, by disconnecting the encoder from the harness, you will postpone the eventual setting of this DTC under normal circumstances. This test helps isolate these circumstances.
  12. Tests the Encoder Feed circuit for proper voltage and that the Encoder Signal Ground circuit has a good ground.
  13. Tests the Encoder Channels for proper voltage.
  14. Tests the Encoder Channels for an open, short to ground or short to voltage.
  15. Tests the Encoder Feed circuit for an open or a short to ground.
  16. Tests the Encoder Signal ground circuit for an open.
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