Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptor
DTC C0321 01: Transfer Case Lock Circuit Short to BatteryDTC C0321 02: Transfer Case Lock Circuit Short to Ground
DTC C0321 04: Transfer Case Lock Circuit Open
DTC C0321 08: Transfer Case Lock Circuit Signal Invalid
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Invalid |
|---|---|---|---|---|
Transfer Case Lock Circuit | DTC C0321 02 | DTC C0321 04 | DTC C0321 01 | DTC C0321 08 |
Circuit/System Description
The transfer case shift control module controls the transfer case lock solenoid.
The transfer case lock solenoid is released by being energized. This is accomplished by grounding the lock solenoid control circuit during gears shifts, and in the AUTO 4WD mode. Locking action is applied when power or ground are taken away from the lock solenoid, the transfer case motor is prevented from moving. The system is capable of providing a 2HI, 4HI and 4LO lock-up without the need of additional vehicle power to hold the transfer case in these positions.
This DTC detects an open lock solenoid coil, open motor lock control circuit, or an open batter positive voltage circuit, or a short to voltage or ground on the lock solenoid control circuit.
Conditions for Running the DTC
| • | The ignition is ON. |
| • | System voltage is 10.5-18 volts. |
Conditions for Setting the DTC
| • | The transfer case shift control module tries to unapply, turn OFF the lock solenoid by grounding the motor control circuit. |
| • | If the module does not sense the battery voltage at the motor lock control circuit prior to applying the motor lock, the DTC sets. |
| • | Transfer Case Lock control reads back as a high voltage when a low voltage is expected. |
Action Taken When the DTC Sets
| • | All shifting is disabled for failure types 01 and 04, normal shifting can occur for failure types 02 and 08. |
| • | The SERVICE 4WD indicator remains illuminated for the remainder of the current ignition cycle. |
Conditions for Clearing the DTC
| • | The transfer case shift control module clears the DTC if the condition for setting the DTC is not currently present. |
| • | A history DTC clears after 40 consecutive warm up cycles without a fault present. |
| • | History DTCs can be cleared using a scan tool. |
Reference Information
Schematic Reference
Transfer Case Control Schematics
Connector End View Reference
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information.
Diagnostic Aids
When the circuits operating the lock solenoid are not complete the lock is engaged. When the circuit is completed the lock is disengaged.
Circuit/System Testing
The battery positive voltage circuit and the lock solenoid control circuit must be tested for opens, shorts to ground, shorts to voltage, and high resistance. This can also result from a electrically faulted solenoid.
- With the ignition on check which DTC is set. If DTC C0321 is set with failure type byte 04 then do the following.
- Disconnect the transfer case actuator, turn on the ignition and with a DMM check the battery positive voltage circuit for battery voltage at the transfer case actuator.
- Disconnect the transfer case control module connector X2 and check the circuit for an open, high resistance, short to ground, or short to voltage. If condition is found repair the circuit or inline connector 109 as necessary, if the condition is not found refer to component testing.
| ⇒ | The transfer case lock is unable to hold during a hold test and the transfer case actuator will need to be replaced, and the motor learn procedure performed. If this is not the case continue to the next step. |
| ⇒ | If battery voltage is not seen then repair the battery positive voltage circuit for an open or high resistance. If the circuit checks out proceed to the next step. |
Component Testing
With the ignition off check the resistance of the lock solenoid with a DMM by probing Pins C and B on the transfer case actuator.
| ⇒ | If the resistance reads 16-42 ohms then replace the transfer case control module, program, and complete the motor learn procedure. If the resistance is not in range then replace the transfer case actuator, and complete the motor learn procedure. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for TCSCM replacement, setup, and programming |
