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 C0387 59: Unable to Complete Shift Circuit/Component Protection TimeoutDiagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Circuit/Component Timeout |
|---|---|---|---|---|
Unable to Complete Shift | -- | -- | -- | DTC C0387 59 |
Circuit/System Description
The transfer case control module commands shifts through motor A and motor B control circuits causing the transfer actuator to shift the transfer case to different modes or ranges depending on driver selection. If the shift lever detent shaft were to bind, or there was a mechanical failure, or motor A control and motor B control were shorted together the shift would not be completed. This will cause the DTC to set in order to protect system components from damage.
Conditions for Running the DTC
| • | The ignition is ON. |
| • | System voltage is 10.5-18 volts. |
Conditions for Setting the DTC
A shift request was received but could not be completed within 15 seconds causing this DTC to set.
Action Taken When the DTC Sets
| • | All shifting is disabled until condition is corrected. |
| • | 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
Motor control A shorting to motor control B could cause this DTC.
Circuit/System Testing
- Ignition off with a DMM check to see if motor A control and motor B control are shorted together after disconnecting the transfer case control module and the transfer case actuator.
- Remove the transfer actuator and check to see if the shift detent shaft is binding.
| ⇒ | If motor A control is shorted to motor B control repair circuits as necessary. If the circuits checked good go to next step. |
| ⇒ | If the shift lever detent shaft is binding refer to Transfer Case Disassemble . If the shift lever detent shaft is not binding replace the transfer case actuator. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
