GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2005 🢒 Optra 🢒 Brakes 🢒 Antilock Brake System 🢒 No Communication with Electronic Brake Control Module

Circuit Description

Battery voltage is supplied to the electronic brake control module (EBCM) through fuse F11 in the instrument panel (I/P) fuse block, to terminal 15 of the EBCM connector. The voltage is present when the ignition switch is in the ON or START position.

This test checks for battery output, proper grounding, blown fuses, a faulty ignition switch, and problems in the circuitry.

Conditions for Setting the DTC
    • The battery is defective.
    • There is a defective ground connection.
    • A connector is damaged.
    •  A wire is broken or shorted.
    • A fuse is blown.
    • The ignition switch is malfunctioning.

Action Taken When the DTC Sets

The antilock brake system (ABS) action is disabled during the period of low voltage.

Diagnostic Aids

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

Test Description

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

  1. This step determines whether there is voltage at the battery and the high current source.

    2.

  2. This step inspects for voltage at the ignition 1 source.

    3.

  3. This step begins the check for voltage at the EBCM end of the ABS harness.

    4.

  4. This step inspects for a defective ground connection.

    5.

  5. This is an inspection for a defective EBCM connector.

Step

Action

Values

Yes

No

1

Measure the voltage at the battery.

Does the voltage measure within the specified range?

11-14 V

Go to Step 3

Go to Step 2

2

Charge or replace the battery as required.

Did you find and correct the condition?

--

System OK

--

3

Inspect fuse EF2 in the engine fuse block.

Is the fuse open?

--

Go to Step 4

Go to Step 8

4
  1. Replace fuse EF2.
  2. Turn the ignition to ON.

Is the fuse open?

--

Go to Step 6

Go to Step 5

5

Inspect the antilock brake system (ABS) function.

Did you complete the action?

--

System OK

--

6
  1. Turn the ignition to OFF.
  2. Remove fuse EF2.
  3. Disconnect the ABS connector from the electronic brake control module (EBCM).
  4. Measure the resistance to ground at terminals 17 and 18.

Is the resistance equal to the specified value?

0 ohms

Go to Step 7

Go to Step 25

7

Repair the short to ground in circuit RD between terminal 1 of the engine fuse block connector C107 and the ABS harness EBCM connector.

Did you complete the repair?

--

System OK

--

8

Inspect fuse EF5 in the engine fuse block.

Is the fuse open?

--

Go to Step 9

Go to Step 13

9
  1. Replace fuse EF5.
  2. Turn the ignition to ON.

Is the fuse open?

--

Go to Step 11

Go to Step 10

10

Inspect the ABS function.

Did you find and correct the condition?

--

System OK

--

11
  1. Turn the ignition to OFF.
  2. Remove fuse EF5.
  3. Disconnect the ABS connector from the EBCM.
  4. Measure the resistance to ground at terminal 15.

Is the resistance equal to the specified value?

0 ohms

Go to Step 12

Go to Step 25

12
  1. Test circuit RD between terminal 4 of engine fuse block connector C105 and terminal 2 of the ignition switch.
  2. Test circuit PK from terminal 4 of the ignition switch to fuse F11 in the instrument panel (I/P) fuse block to terminal 15 of the ABS EBCM connector.
  3. Repair any short to ground found in the wiring or the ignition switch.

Did you find and correct the condition?

--

System OK

--

13

Inspect fuse F11 in the I/P fuse block.

Is the fuse open?

--

Go to Step 14

Go to Step 18

14
  1. Replace fuse F11.
  2. Turn the ignition to ON.

Is the fuse open?

--

Go to Step 16

Go to Step 15

15

Inspect the ABS function.

Is the repair complete?

--

System OK

--

16
  1. Turn the ignition to OFF.
  2. Remove fuse F11.
  3. Disconnect the ABS connector from the EBCM.
  4. Measure the resistance to ground at terminal 15.

Is the resistance equal to the specified value?

0 ohms

Go to Step 17

Go to Step 25

17

Repair the short to ground in circuit PK fuse F11 of the I/P fuse block and terminal 15 of the ABS harness EBCM connector.

Did you complete the repair?

--

System OK

--

18
  1. Disconnect the EBCM connector from the EBCM.
  2. Turn the ignition to ON.
  3. Measure the presence of battery voltage between ground and terminal 17, and between ground and terminal 18.

Does the voltage measure within the specified range?

11-14 V

Go to Step 20

Go to Step 19

19
  1. Turn the ignition switch to OFF.
  2. Trace the RD wires between terminals 17 and 18 of the EBCM connector to terminal 1 of connector C107 at the engine fuse block.
  3. Repair the open in this circuit.

Did you complete the repair?

--

System OK

--

20

Measure the voltage between ground and terminal 15 of the EBCM connector.

Does the voltage measure within the specified range?

11-14 V

Go to Step 22

Go to Step 21

21
  1. Turn the ignition switch to OFF.
  2. Test circuit PK between terminal 15 of the ABS harness EBCM connector to fuse F11 in the I/P fuse block.
  3. Test circuit PK from fuse F11 of the I/P fuse block to terminal 4, IG1, of the ignition switch.
  4. Test circuit RD from terminal 2, B1, of the ignition switch to terminal 4 of connector C105 at the engine fuse block and to fuse EF5.
  5. Repair the open in the wiring or possibly bad connector terminal, defective ignition switch, or blown fuse EF5.

Did you find and correct the condition?

--

System OK

--

22
  1. Turn the ignition to OFF.
  2. Measure the resistance between ground and terminals 19 and 16 of the EBCM connector.

Is the resistance equal to the specified value?

0 ohms

Go to Step 23

Go to Step 26

23

Test terminals 15, 19, 17, 18, and 16 of the EBCM connector.

Is there a defective terminal?

--

Go to Step 24

Go to Step 25

24

Repair the defective terminal or replace the connector or wiring harness as required.

Did you complete the repair?

--

System OK

--

25

Replace the ABS unit.

Did you complete the replacement?

--

System OK

--

26

Repair the defective ground connection.

Did you complete the repair?

--

System OK

--