For 1990-2009 cars only
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 Descriptors
DTC C0550 00: Electronic Control Unit (ECU) PerformanceDTC C0550 31: Electronic Control Unit (ECU) Performance
DTC C0550 32: ECU Performance General Memory Failure
DTC C0550 34: ECU Malfunction RAM Failure
DTC C0550 35: ECU Malfunction ROM Failure
DTC C0550 36: ECU Malfunction EEPROM Failure
DTC C0550 37: ECU Malfunction Watch Dog failure
DTC C0550 38: ECU Performance Supervision Software Failure
DTC C0550 39: ECU Performance Internal Electronic Failure/Discard
DTC C0550 4B: ECU Internal Fault
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
| • | 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. The DTC should clear.
- 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 will not clear, replace the control module. |
| ⇒ | If DTC C0550 sets, 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
