GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2006 🢒 Optra - Mexico 🢒 Vehicle Control Systems 🢒 Vehicle DTC Information 🢒 ABS Indicator Always On

Circuit Description

Battery voltage is supplied to the antilock brake system (ABS) warning lamp with the ignition switch in the ON or START position. The warning lamp should be activated only by the ABS control module internally supplying ground to terminal 20.

This procedure checks for a short to ground in the wiring or a defective electronic brake control module (EBCM).

Conditions for Running the DTC

Ignition is in the On or Start position.

Conditions for Setting the DTC
    • There is a short to ground in the circuit between the cluster terminal A13 and the EBCM terminal 20.
    •  The EBCM is faulty.

Action Taken When the DTC Sets

The following actions occur:

    • The ABS is disabled.
    • The ABS warning indicator turns is ON.
    • The electronic brake force distribution (EBD) is enabled.

Conditions for Clearing the DTC

The condition responsible for setting the DTC no longer exists and the scan tool Clear DTCs function is used.

Test Description

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

  1. This step determines whether the EBCM is faulty.

    2.

  2. This begins a search for a short to ground in the circuit between the ABS indicator lamp and the EBCM.

Step

Action

Yes

No

Schematic Reference: Antilock Brake System Schematics

Connector End View Reference: Antilock Brake System Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

Inspect the electronic brake control module (EBCM) connector.

Is it connected properly?

Go to Step 4

Go to Step 3

3

Connect the EBCM connector.

Did you find and correct the condition?

Go to Step 9

--

4

  1. Disconnect the EBCM connector.
  2. Turn the ignition switch to ON.
  3. Use an insulated tool to push the shorting bar in the connector away from terminal 20.

Does the antilock brake system (ABS) indicator lamp go out?

Go to Step 5

Go to Step 6

5

Replace the ABS unit.

Did you complete the replacement?

Go to Step 9

--

6

  1. Turn the ignition switch to OFF.
  2. Connect the EBCM connector.
  3. Disconnect connector C110.
  4. Turn the ignition switch to ON.

Does the ABS indicator lamp illuminate?

Go to Step 8

Go to Step 7

7

Repair the short to ground in circuit L-GN between connector C110 and the EBCM connector.

Did you complete the repair?

Go to Step 9

--

8

Repair the short to ground in circuit L-GN between the instrument panel cluster (IPC) connector A13 and connector C110.

Did you complete the repair?

Go to Step 9

--

9

Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Is the repair complete?

System OK

Go to Step 2