GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2005 🢒 Optra 🢒 Brakes 🢒 Antilock Brake System 🢒 ABS Indicator Inoperative

Circuit Description

Battery voltage is supplied to the antilock brake system (ABS) warning lamp with the ignition switch in the ON or START positions. The warning lamp can be activated only by the ABS control module internally supplying ground to terminal 20 or by the shorting bar in the ABS module connector when it is disconnected from the module.

This procedure inspects for a problem in the wiring, a faulty ground, a voltage supply problem, a burned out indicator lamp, or a contact problem in a connector.

Conditions for Setting the DTC
    • A fuse has blown.
    • The indicator lamp has burned out.
    • There is a corroded or broken connector terminal.
    • There is a faulty ground connection.
    • There is a broken wire in a wiring harness.
    • The electronic brake control module (EBCM) is faulty.

Test Description

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

  1. This test checks for any diagnostic trouble codes (DTCs) that may cause the ABS indicator lamp to be inoperative.

    2.

  2. This test verifies an inoperative lamp condition.

    3.

  3. This test checks for voltage on the lamp circuit.

    4.

  4. This begins a series of tests of the circuit from the indicator lamp to the EBCM and ground.

    5.

  5. This begins a series of tests of the voltage supply circuits that power the indicator lamp.

Step

Action

Values

Yes

No

1

Install the scan tool and check for any diagnostic trouble codes (DTCs).

Is any DTC set?

--

Go to Diagnostic Trouble Code (DTC) List

Go to Step 2

2

  1. Turn the ignition switch to LOCK.
  2. Disconnect the scan tool.
  3. Turn the ignition switch to ON.
  4. Observe the antilock brake system (ABS) indicator lamp.

Does the lamp illuminate for about 4 seconds, then turn OFF?

--

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3

With the ignition still ON, observe the oil pressure lamp.

Is the oil pressure lamp illuminated?

--

Go to Step 4

Go to Step 19

4

  1. Turn the ignition switch to LOCK.
  2. Disconnect the connector from the electronic brake control module (EBCM).
  3. Turn the ignition switch to ON.

Does the ABS indicator illuminate?

--

Go to Step 5

Go to Step 8

5
  1. Turn the ignition switch to LOCK.
  2. Test terminals 19 and 20 at the EBCM connector on both the ABS wiring harness and on the EBCM.

Is there a poor connection at any of these terminals?

--

Go to Step 6

Go to Step 7

6

Repair the faulty terminals or replace the ABS unit as required.

Did you complete the repair?

--

System OK

--

7

Replace the ABS unit.

Did you complete the replacement?

--

System OK

--

8
  1. Turn the ignition switch to LOCK.
  2. Disconnect the wire from the negative battery terminal.
  3. Measure the resistance between the negative battery wire, which is attached to ground, and the shorting bar in the EBCM connector.

Is the resistance equal to the specified value?

0 ohms

Go to Step 10

Go to Step 9

9

Repair the open or high resistance in the circuit from the EBCM connector, terminal 19 to ground G106.

Did you complete the repair?

--

System OK

--

10
  1. Remove the instrument panel cluster (IPC).
  2. Remove and inspect the ABS indicator bulb.

Is the bulb burned out?

--

Go to Step 11

Go to Step 12

11
  1. Replace the ABS indicator bulb.
  2. Install the IPC.

Did you complete the repair?

--

System OK

--

12

Test the continuity at the IPC connector terminal A13.

Does the ohmmeter show the specified value?

0 ohms

Go to Step 14

Go to Step 13

13

Repair the contact at the IPC connector terminal A13.

Did you complete the repair?

--

System OK

--

14

Inspect the wiring harnesses and the connectors in circuit L-GN/BK from the IPC terminal A13 to terminal 20 of the EBCM connector.

Does the ohmmeter show the specified value?

∞

Go to Step 15

Go to Step 16

15

Repair the open or high resistance found.

Did you complete the repair?

--

System OK

--

16

Test for continuity between terminal 19 of the ABS connector and ground G106.

Is the ground connection equal to the specified value?

0 ohms

Go to Step 17

Go to Step 18

17

Replace the ABS unit.

Did you complete the replacement?

--

System OK

--

18

Repair the continuity problem between terminal 19 of the EBCM connector and ground G106.

Did you complete the repair?

--

System OK

--

19

  1. Turn the ignition switch to LOCK.
  2. Inspect fuse F4 in the I/P fuse block.

Is the fuse open?

--

Go to Step 20

Go to Step 21

20

Replace fuse F4.

Did you complete the replacement?

--

System OK

--

21

Inspect fuse EF5 in the engine fuse block.

Is the fuse open?

--

Go to Step 22

Go to Step 23

22

Replace fuse EF5.

Did you complete the replacement?

--

System OK

--

23

Measure the voltage at terminal 2 of the ignition switch connector by backprobing.

Does the voltage measure within the specified range?

11-14 V

Go to Step 25

Go to Step 24

24
  1. Inspect circuit RD between terminal 4 of C105 at the engine fuse block and terminal 2 of the ignition switch for continuity.
  2. Repair any open or high resistance found.

Did you find and correct the condition?

--

System OK

--

25
  1. Turn the ignition switch to ON.
  2. Backprobe terminal 4, PK, of the ignition switch connector.

Is the voltage within the specified range?

11-14 V

Go to Step 27

Go to Step 26

26

Replace the ignition switch.

Did you complete the replacement?

--

System OK

--

27
  1. Turn the ignition switch to LOCK.
  2. Inspect circuit PK from terminal 4 of the ignition switch to fuse F4 in the I/P fuse block.

Does the ohmmeter show the specified value?

∞

Go to Step 28

Go to Step 29

28

Repair the open or the high resistance.

Did you complete the repair?

--

System OK

--

29
  1. Remove the IPC.
  2. Inspect circuit PK from fuse F4 to terminal A19 of the IPC connector B.
  3. Repair any open or high resistance found in a wiring harness, splice pack, or connector.

Did you complete the repair?

--

System OK

--