C0387

DTC C0387

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 Timeout




Diagnostic Fault Information






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 (Electrical Diagrams)
Connector End View Reference

Component Connector End Views
Electrical Information Reference

* Circuit Testing
* Connector Repairs
* Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs

Scan Tool Reference

* Scan Tool Data List (Scan Tool Data List)
* Scan Tool Data Definitions (Scan Tool Data Definitions)



Diagnostic Aids

Motor control A shorting to motor control B could cause this DTC.


Circuit/System Testing

1. 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.

• If motor A control is shorted to motor B control repair circuits as necessary. If the circuits checked good go to next step.

2. Remove the transfer actuator and check to see if the shift detent shaft is binding.

• If the shift lever detent shaft is binding refer to Transfer Case Disassemble (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.

* Transfer Case Two/Four Wheel Drive Actuator Replacement (Transfer Case Two/Four Wheel Drive Actuator Replacement)
* Transfer Case Disassemble (Transfer Case Disassemble)