Diagnostic Instructions
DTC Descriptor
DTC C0327: Encoder Circuit Malfunction
Circuit/System Description
The transfer case shift control module has 4 encoder circuits, and each circuit is supplied 12 volts. These 4 circuits are A, B, C, and P, and each circuit runs to a switch located inside the encoder/motor assembly. When a particular
encoder circuit is active, the switch is closed, and the 12 volts are grounded by the switch inside the encoder. The transfer case shift control module supplies 12 volts on all the circuits. The module can interpret the location of the transfer
case shift position when the circuits are grounded.
This DTC detects a fault when it compares the shift sequence/strategy to a chart located in read only memory (ROM) within the transfer case shift control module. This is accomplished by the module reading the different combinations of encoder signals
being grounded while others remain high depending on what mode or range the transfer case is in.
Conditions for Running the DTC
| • | The system voltage is 10-16 volts. |
Conditions for Setting the DTC
This DTC sets when the encoder signals does not match the control strategy contained in the transfer case shift control module.
Action Taken When the DTC Sets
| • | All motor activity will stop. |
| • | All accessory switch mode indicators will be commanded OFF. |
| • | The SERVICE 4WD indicator will be on until the fault is corrected. |
| • | If a new mode is requested by the driver with either a current or history DTC , the transfer case control module will only allow a shift to 2WD mode. The transfer case control module will not allow further mode changes. |
Conditions for Clearing the DTC
| • | The DTC will set as both current and history. |
| • | A scan tool must be used in order to clear a DTC. |
Diagnostic Aids
A low battery condition or charging system that is faulty could set this DTC. Refer to
Battery Inspection/Test
and
Charging System Test
.
Reference Information
Schematic Reference
Transfer Case Control Schematics
Connector End View Reference
Component Connector End Views
Description and Operation
Transfer Case Description and Operation
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References
for scan tool information
Circuit/System Verification
- Ignition ON, engine OFF, command each mode function switch ON one at a time, on the instrument panel accessory switch. Each mode button indicator light should illuminate.
- Road test the vehicle in 4LO, 4HI, Neutral, and 2HI. The transfer case should shift into and out of each mode, while operating the vehicle.
- Operate the vehicle within the conditions for running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records Data.
Circuit/System Testing
Important: You must perform the Circuit/System Verification before proceeding to Circuit/System Testing.
- Ignition OFF, disconnect the transfer case encoder motor electrical connector.
- Verify that a test lamp illuminates between B+ and terminal E of the transfer case encoder motor connector.
| ⇒ | If the test lamp does not illuminate, test the ground circuit for an open/high resistance. |
- Ignition ON, measure for 11-13 volts on terminals A, F, G, H, of the transfer case encoder motor connector.
| ⇒ | If less than the specified range, test the circuit for a short to ground or an open/high resistance. If the circuits test normal, replace the transfer case shift control module. |
- Ignition OFF, disconnect the transfer case shift control module.
- Using a DMM, verify that no continuity is detected between each channel encoder signal circuit.
| ⇒ | If continuity is detected between the circuits, repair as necessary. |
| ⇒ | If all circuits test normal, replace the transfer case encoder motor. |
Repair Instructions
Perform the
Diagnostic Repair Verification
after completing the diagnostic procedure.
