GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2005 🢒 Optra 🢒 Brakes 🢒 Antilock Brake System 🢒 DTC C0550

Circuit Description

The antilock brake system (ABS) control module performs various diagnostic checks on itself. If it finds a problem, it sets DTC C0550.

This procedure checks whether there is a poor ground connection for the electronic brake control module (EBCM).

Conditions for Setting the DTC
    • A connector terminal is corroded.
    • The EBCM is malfunctioning.

Action Taken When the DTC Sets

The ABS is disabled, and the ABS warning lamp is turned ON. The electronic brake force distribution (EBD) is disabled. If the failure is intermittent, the control module will enable the system at the next ignition cycle and will store a history DTC C0550.

Diagnostic Aids

It is very important to perform a thorough inspection of the wiring and the connectors. Failure to inspect the wiring and the connectors carefully and completely may result in misdiagnosis, causing part replacement with the reappearance of the malfunction.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. This step begins the testing for a poor voltage or ground connection.

Step

Action

Values

Yes

No

1

Use the scan tool to determine if any other DTCs are set.

Are other DTCs set?

--

Go to Diagnostic Trouble Code (DTC) List

Go to Step 2

2

Clear all DTCs and road test the vehicle.

Does DTC C0550 set again?

--

Go to Step 4

Go to Step 3

3

  1. Inspect all wiring harness connectors and terminals, especially those at the electronic brake control module (EBCM), for any condition that could cause an intermittent.
  2. Repair any problems found.

Did you find and correct the condition?

--

System OK

--

4
  1. Turn the ignition switch to OFF.
  2. Disconnect the EBCM connector J1.
  3. Turn the ignition switch to ON.
  4. Measure the voltage between ground and terminals 15, 17, and 18 of the EBCM harness connector J1.

Does the voltage measure within the specified range?

11-14 V

Go to Step 6

Go to Step 5

5
  1. Inspect the voltage supply and the ground connections to the EBCM.
  2. Repair any open or high resistance found.

Did you find and correct the condition?

--

System OK

--

6

Inspect the EBCM connector J1 for any ineffective terminals.

Are there any ineffective terminals?

--

Go to Step 7

Go to Step 8

7

Repair any connector problem found.

Did you complete the repair?

--

System OK

--

8

Clear all DTCs and road test the vehicle.

Does DTC 0550 set again?

--

Go to Step 9

System OK

9

Replace the antilock brake system (ABS) unit.

Did you complete the replacement?

--

System OK

--