Fault Code 1256 arises in the QSK CM2358 due to an issue with the Control Module Identification Input State, indicating data that may be erratic, intermittent, or incorrect. This state of incorrect identification can lead to various engine performance issues, including rough operation, engine shutdown, failure to start, or difficulties in starting.
Associated Resources:
Circuit Overview: The engine’s control module (ECM) utilizes the control module identification circuit to confirm its proper connection within the wiring harness. This is determined through a specific configuration of signal pins connected to the circuit, allowing the ECM to identify its correct position.
Location of Components: The control module identification circuit is integrated into the engine’s wiring harness.
Diagnostic Activation Conditions: This diagnostic is activated upon turning the key to the ON position for the first time.
Fault Code Activation Conditions: The fault code is set off when an invalid input through the control module identification circuit is detected.
Consequences of an Active Fault Code: Upon detection and failure of the diagnostic, the ECM immediately activates the amber CHECK ENGINE light.
Fault Code Clearance: To verify that the issue has been resolved:
- Perform a key cycle, leaving the key in the ON position for 1 minute.
- The fault code status, as shown by the appropriate diagnostic tool, will shift to INACTIVE after the diagnostic successfully completes.
- The amber CHECK ENGINE light will be deactivated by the ECM following a successful diagnostic.
- The “Reset All Faults” function in the diagnostic software can be used to clear both active and inactive fault codes.
Technical Notes (Shop Talk): Potential causes for this fault code include open or short circuits in one or more of the control module identification signal wires.
Further Guidance: For additional troubleshooting information on the QSK60 CM2358, consult the relevant repair documentation.