NVG 126-NP4 - Transfer Case

DTC C0550

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 Instructions)provides an overview of each diagnostic category.

DTC Descriptor
DTC C0550
^ ECU Malfunction

Circuit/System Description

At each power-up, the transfer case shift control module runs a self-test on the following:

* EEPROM Checksum
* ROM Checksum
* RAM Checksum
* RAM Malfunction

Conditions for Running the DTC

* The ignition is ON.
* System voltage is 9-18 volts.

Conditions for Setting the DTC

* Critical operational parameters stored in EEPROM have failed Checksum test indicating invalid data.
* Masked ROM code has failed Checksum test indicating that masked ROM data is no longer valid.
* ROM code has failed Checksum test indicating that ROM data is no longer valid.
* One or more ROM locations have failed operational test indicating that some portions of RAM are not functional.

Action Taken When the DTC Sets

* The SERVICE AWD indicator remains illuminated for the remainder of the current ignition cycle.
* The transfer case control switch does not display the current position LED while DTC C0550 is current.

Conditions for Clearing the DTC

* Replace the transfer case shift control module.
* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle).

Reference Information
Schematic Reference

Transfer Case Control Schematics (Electrical Diagrams)
Connector End View Reference

Component Connector End Views ()
Description and Operation

Transfer Case Description and Operation (NVG 126-NP4 - Transfer Case)
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

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

Circuit/System Verification

TBD

Circuit/System Testing

TBD

Component Testing

TBD

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

Repair Verification

TBD