GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2007 🢒 DTS 🢒 Suspension 🢒 Air Suspension 🢒 DTC C0550

Circuit Description

The internal fault detection is handled inside the control module. No external circuits are involved.

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

34

RAM Failure

35

ROM Failure

36

EEPROM Failure

37

Watch Dog Mc Failure

38

Supervision Software Failure

39

Internal Electronic Failure

Conditions for Running the DTC

The microprocessor runs the 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.

Action Taken When the DTC Sets

If equipped, the following module specific actions may occur:

    • Air suspension functionality is suspended
    • SERVICE SUSPENSION message is displayed

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 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 the DTCs.

Is the DTC retrieved as a current DTC?

Go to Step 3

Go to Diagnostic Aids

3

Replace the air suspension control module. Refer to Air Suspension Control Module Replacement .

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