GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2005 🢒 Cobalt 🢒 Restraints 🢒 SIR 🢒 DTC C0550

Circuit Description

The internal fault detection is handled inside the control module. No external circuits are involved. DTC C0550 is set when an internal malfunction takes place within the control module.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC C0550 Electronic Control Unit (ECU) Performance

This vehicle has DTCs which include DTC Symptoms. For more information on DTC Symptoms, refer to DTC Symptom Description .

DTC Symptom

DTC Symptom Descriptor

00

No Additional Information

39

Internal Electronic Failure

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. This program runs even if the voltage is out of the valid operating range.

Conditions for Setting the DTC
    • The control module detects an internal write malfunction.
    • The control module detects an internal checksum malfunction.

Conditions for Clearing the DTC
    • A current DTC clears when the malfunction is no longer present.
    • A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.

Diagnostic Aids
    • This DTC may be stored as a history DTC without affecting the operation of the module. If stored only as a history DTC and not retrieved as a current DTC, do not replace the module.
    • If this DTC is retrieved as both a current and a history DTC, replace the module.
    • If this DTC continues to set intermittently, replace the module.

Step

Action

Yes

No

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2
  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. Retrieve DTCs.

Is the DTC retrieved as a current DTC?

Go to Step 3

Go to Diagnostic Aids

3

Important: Perform the programming or setup procedure for the module, if required.

Replace the control module setting the DTC as current. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 4

--

4
  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC, as specified in the supporting text.

Does the DTC reset?

Go to Step 2

System OK