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: EEPROM Checksum MismatchDTC C0550 39: EEPROM Checksum Mismatch
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 antilock brake system (ABS) indicator turns ON. |
| • | The BRAKE warning indicator turns ON. |
| • | The electronic brake control module (EBCM) disables the ABS/dynamic rear proportion (DRP)/traction control system (TCS). |
| • | The driver information center (DIC) displays the power steering warning message No Steering Assist. |
| • | The TCS indicator turns ON. |
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. |
Reference Information
Schematic Reference
Connector End View Reference
Data Communication Connector End Views
Description and Operation
Data Link Communications Description and Operation
Electrical Information Reference
Scan Tool Reference
Circuit/System Verification
Verify that DTC C0550 is not set.
| ⇒ | If the DTC is set, perform the learn procedure on the control module. If the DTC resets, replace the applicable control module. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for control module replacement, setup, and programming
