Diagnostic Instructions
DTC Descriptors
DTC C0550: ECU Malfunction
Circuit/System Description
When the ignition is turned ON, the microprocessor runs a diagnostic program to detect an internal fault when power up is commanded. If an internal malfunction is detected, the control module will store a DTC C0550 in its memory.
Conditions for Running the DTC
The microprocessor runs a diagnostic program to detect an internal fault when power up is commanded. The only requirements are voltage and ground.
Conditions for Setting the DTC
| • | The control module detects an internal write malfunction. |
| • | The control module detects an internal checksum malfunction. |
Action Taken When the DTC Sets
If equipped, the following module specific actions may occur:
| • | The affected system warning indicator/warning message will activate. |
| • | The affected system will be disabled. |
Conditions for Clearing the DTC
| • | A current DTC clears when the malfunction is no longer present. |
| • | A history DTC clears when the control module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction. |
Circuit/System Verification
- With a scan tool, clear DTC C0550.
| ⇒ | If the DTC will not clear, replace the control module. |
- Ignition OFF, remove the scan tool, open and close the drivers door.
- Wait 60 seconds, ignition ON, then recheck for DTCs. DTC C0550 should not set.
| ⇒ | If the DTC resets, replace the module. |
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for control module replacement, setup, and programming
