MP 3010-NP0 - Transfer Case
DTC C0396
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructionsprovides an overview of each diagnostic category.
DTC Descriptors
DTC C0396 01
- Incremental Sensor Circuit Short to Battery
DTC C0396 02
- Incremental Sensor Circuit Short to Ground
DTC C0396 04
- Incremental Sensor Open Circuit
DTC C0396 05
- Incremental Sensor Circuit Short to Battery or Open
Diagnostic Fault Information
Circuit/System Description
The transfer case incremental position sensor (IPS) and the transfer case rotational position sensor (RPS) both send current transfer case mode/range position to the transfer case shift control module (TCCM). Both sensors send this information as voltage signals which are converted to degrees and rotational direction by the TCCM software. If the two sensors disagree by greater than a predetermined amount, the DTC will set.
The IPS receives an 8 volt reference signal from the TCCM and sends back a transfer case incremental position signal and an encoder rotational direction signal.
The RPS (also known as the transfer case two/four wheel drive actuator position sensor) receives a 5 volt reference signal from the TCCM and sends back a continuously variable pulse width modulated signal to the TCCM. This continuously variable signal indicates the position of the transfer case actuator.
The IPS is more sensitive than the RPS, but needs to reference the RPS value at key-up and mode changes. The RPS is an absolute sensor. The TCCM syncs the IPS with the RPS at key-up and mode changes.
The IPS is an integral part of the transfer case actuator and cannot be replaced independently.
The RPS is an independently replaceable part.
Conditions for Running the DTC
* Ignition ON.
* System voltage 10.5-18 V.
Conditions for Setting the DTC
C0396 01
Voltage on incremental encoder sensor 8 V supply circuit greater than 9.0 V.
C0396 02
Incremental encoder sensor 8 V supply circuit less than 1.5 V, or voltage on incremental encoder impulse signal circuit or incremental encoder direction signal circuit less than 0.5 V.
C0396 04
Voltage on encoder 8 V supply circuit is 1.5-9.0 V and voltage read by low reference circuit less than 0.3 V.
C0396 05
Voltage on encoder signal circuits less than 0.3 V or greater than 4.6 V.
Action Taken When the DTC Sets
C0396 01 and C0396 05
* All shifting disabled.
* The SERVICE 4WD indicator remains illuminated for the remainder of the current ignition cycle.
* Incremental encoder sensor (8 V) supply shut OFF.
C0396 02 and C0396 04
* All shifting disabled.
* The SERVICE 4WD indicator remains illuminated for the remainder of the current ignition cycle.
Conditions for Clearing the DTC
* The TCCM clears the DTC once the conditions for setting the DTC no longer exist.
* A history DTC clears after 40 consecutive warm up cycles without a fault present.
* History DTCs can be cleared using a scan tool.
Diagnostic Aids
* The incremental position sensor and the rotational position sensor both show position in degrees and should track each other. Monitor these sensors for erratic or unreasonable readings.
* If the incremental position sensor is determined to be bad, the entire transfer case actuator will have to be replaced, as the incremental sensor is part of the actuator and cannot be replaced independently.
* The transfer case fill and drain plugs are good sources for ground.
Reference Information
Schematic Reference
Transfer Case Control Schematics MP 3010-NP0 - Transfer Case
Connector End View Reference
Component Connector End Views Connector End Views By Name
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
Scan Tool Reference
Control Module References Programming and Relearningfor scan tool information.
Special Tools
* EL-49741 - 9 V+ Power Source Harness
* EL-49742 - Battery Voltage B+ and Ground Source Harness
* J 35616 - GM-Approved Terminal Test Kit
Circuit/System Verification
1. Key ON, engine OFF.
2. Connect a scan tool.
3. Monitor the IPS and RPS parameters on the scan tool. Using the transfer case encoder motor, shift the transfer case into all modes. The IPS and RPS parameters should track each other.
Circuit/System Testing
Note: When test probing harness terminals, it is imperative to use the proper test probe from the most current version of the J 35616 - GM-Approved Terminal Test Kit. Use of an improper test probe may deform the terminal, resulting in intermittent open conditions.
1. Key OFF. Disconnect the X1 connector at the transfer case encoder motor (TCEM).
2. Key ON, engine OFF.
3. Attach scan tool. If DTC C0396-05 is set, test the following circuits for an open/high resistance or short to voltage condition.
* Incremental Encoder Impulse Signal
* Incremental Encoder Direction Signal
4. Clear codes. DTC C0396-04 may remain in memory.
5. Using the PU probe J 35616-4A, test for 7.50-8.50 V between the incremental encoder sensor (8 V) supply circuit, TCEM X1 pin G and a good ground.
• If the voltage is greater than the specified range, test the affected circuit for a short to voltage. If all circuits and connections test normal, test the TCCM for proper operation.
• If the voltage is less than the specified range, test the affected circuit for a short to ground, an open/high resistance or short to voltage. If all circuits and connections test normal, TCCM for proper operation.
6. Using the PU probes J 35616-4A, test for 7.50-8.50 V between the incremental encoder sensor (8 V) supply circuit, TCEM X1 pin G and the low reference circuit, TCEM X1 pin H.
• If the voltage is greater than the specified range, test the low reference circuit for a short to voltage. If all circuits and connections test normal, test the TCCM for proper operation.
• If the voltage is less than the specified range, test the low reference circuit for a short to ground, an open/high resistance or short to voltage. If all circuits and connections test normal, test the TCCM for proper operation.
7. Using the PU probe J 35616-4A, test for 6.0-7.0 V between the incremental encoder impulse signal circuit, TCEM X1 pin E and a good ground.
• If the voltage is greater than the specified range, test the affected circuit for a short to voltage. If all circuits and connections test normal, test the TCCM for proper operation.
• If the voltage is less than the specified range, test the affected circuit for a short to ground, an open/high resistance or short to voltage. If all circuits and connections test normal, test the TCCM for proper operation.
8. Using the PU probe J 35616-4A, test for 6.0-7.0 V between the incremental encoder direction signal circuit, TCEM X1 pin F and a good ground.
• If the voltage is greater than the specified range, test the affected circuit for a short to voltage. If all circuits and connections test normal, test the TCCM for proper operation.
• If the voltage is less than the specified range, test the affected circuit for a short to ground, an open/high resistance or short to voltage. If all circuits and connections test normal, test the TCCM for proper operation.
9. Using the PU probe J 35616-4A, test for greater than 500 ohm between the incremental encoder sensor (8 V) supply circuit, TCEM X1 pin G and all other pins of the TCEM X1.
• If the resistance is less than the specified range, test the affected circuits for a shorted together condition. If all circuits and connections test normal, test the TCCM for proper operation.
10. Using the PU probe J 35616-4A, test for greater than 500 ohm between the incremental encoder impulse signal circuit, TCEM X1 pin E and all other pins of the TCEM X1.
• If the resistance is less than the specified range, test the affected circuits for a shorted together condition. If all circuits and connections test normal, test the TCCM for proper operation.
11. Using the PU probe J 35616-4A, test for greater than 10 ohm between the incremental encoder direction signal circuit, TCEM X1 pin F and all other pins of the TCEM X1.
• If the resistance is less than the specified range, test the affected circuits for a shorted together condition. If all circuits and connections test normal, test the TCCM for proper operation.
12. Using the PU probe J 35616-4A, test for greater than 10 ohm between the low reference circuit, TCEM X1 pin H and all other pins of the TCEM X1.
• If the resistance is less than the specified range, test the affected circuits for a shorted together condition. If all circuits and connections test normal, test the TCCM for proper operation.
13. Test the TCEM for proper operation.
Component Testing
TCEM - Incremental Position Sensor
1. Set parking brake.
2. Block wheels.
3. Remove the encoder motor from transfer case. Using a paint pen or marker, place indexing marks on the shift detent lever receiver and the mounting surface of the encoder motor.
4. Connect encoder motor to engine harness.
5. Key ON, engine OFF.
6. Transmission in Neutral.
7. Attach scan tool. Clear codes. DTC C0569-4B may remain in memory.
Note: You must perform the Transfer Case High/Low Clutch Reset Transfer Case High/Low Clutch Reset procedure after performing the next step.
8. Monitor the following parameters while using the Transfer Case Motor Control function of the Special Function feature of the scan tool to command the encoder motor forward and reverse. The parameters should display as shown.
• If the parameters do not display as described, replace the encoder motor assembly.
TCCM
1. Key OFF. Disconnect the TCCM X1 connector.
2. Key ON, engine OFF. Connect the EL-49742 - harness.
3. Test for 7.5-8.5 V between the incremental encoder sensor (8 V) supply pin, TCCM X1-9, and the ground terminal of the EL-49742 - harness , black terminal.
• If the outside the specified range, replace TCCM.
4. Test for 7.5-8.5 V between the incremental encoder sensor (8 V) supply pin, TCCM X1-9, and the low reference pin, TCCM X1-10.
• If the outside the specified range, replace TCCM.
5. Test for 6.0-7.0 V between the incremental encoder impulse signal pin, TCCM X1-3, and the ground terminal of the EL-49742 - harness , black terminal.
• If the outside the specified range, replace TCCM.
6. Key OFF. Connect the TCCM X1 connector. Disconnect the TCCM X2 connector.
7. Key OFF. Test for a diagnostic B+ (+0.0/-1.0 V) between the incremental encoder direction pin, TCCM X2-14, and the B+ terminal of the EL-49742 - harness , red terminal.
• If the outside the specified range, replace TCCM.
8. Go to Circuit/System testing.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Control Module References Programming and Relearningfor TCSCM replacement, setup, and programming
* Transfer Case High/Low Clutch Reset Transfer Case High/Low Clutch Reset
* Transfer Case Two/Four Wheel Drive Actuator Replacement Transfer Case Two/Four Wheel Drive Actuator Replacement