GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2004 🢒 Safari - 2WD 🢒 DTC 🢒 DTC C0550

Circuit Description

Each control module runs a program to detect internal memory faults. No external circuits are involved. If a memory fault is detected, that control module may set DTC C0550.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC C0550 Electronic Control Unit (ECU) Performance

Conditions for Running the DTC
    • The control module has power and ground.
    • The ignition is ON.

Conditions for Setting the DTC

DTC C0550 will set if either of the following conditions occur:

    • 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 ABS indicator turns ON.
    • The BRAKE Warning indicator turns ON.
    • The SERVICE 4WD indicator turns ON and the system will be disabled.
    • The SERVICE RIDE SYS or SERVICE RIDE CONTROL message is displayed.
    • The SERVICE SUSPENSION SYS message is displayed.
    • 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 ignition is cycled 100 times without a repeat of the malfunction.

Diagnostic Aids
    • DTC C0550 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 DTC C0550 is retrieved as both a current and history DTC, replace the module that set the DTC.

Step

Action

Yes

No

1

Did you perform the Diagnostic System Check for the system exhibiting the symptom?

Go to Step 2

Go to Control Module References for the applicable Diagnostic System Check

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

Is DTC C0550 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 .

Did you complete the replacement?

Go to Step 4

--

4
  1. Clear the DTCs with the scan tool.
  2. Operate the vehicle within the Conditions for Running the DTC.

Does DTC C0550 reset?

Go to Step 2

System OK