GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2004 🢒 Optra 🢒 DTC 🢒 DTC C0800

Circuit Description

Proper operation of the electronic brake control module (EBCM) requires a certain minimum voltage. The EBCM monitors the ignition feed circuit to determine if the voltage falls below a minimum level.

This test inspects for battery output, proper grounding, blown fuses, 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, and the ABS warning lamp is ON for the remainder of the ignition cycle. If the failure is intermittent, the EBCM will enable the system at the next ignition cycle and set a history DTC C0800.

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 at the high current source.

    2.

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

    3.

  3. This step begins the test 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 value?

11-14 V

Go to Step 3

Go to Step 2

2

Charge or replace the battery as required.

Did you complete the action?

--

System OK

--

3

Inspect fuse EF2 in the engine fuse block.

Is the fuse open?

--

Go to Step 4

Go to Step 7

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

Is the fuse open?

--

Go to Step 5

Go to Step 6

5
  1. Turn the ignition to OFF.
  2. Test the RD wires in the antilock brake system (ABS) wiring harness from terminal 1 of C107 at the engine fuse block to terminals 17 and 18 of the electronic brake control module (EBCM) connector.
  3. Repair any short circuit found along this path.

Did you find and correct the condition?

--

System OK

--

6
  1. Turn the ignition switch to OFF.
  2. Install the scan tool.
  3. Clear all diagnostic trouble codes (DTCs).
  4. Road test the vehicle.

Does DTC C0800 reset?

--

System OK

--

7

Inspect fuse F11 in the instrument panel (I/P) fuse block.

Is the fuse open?

--

Go to Step 8

Go to Step 11

8
  1. Replace fuse F11.
  2. Turn the ignition to ON.

Is the fuse open?

--

Go to Step 9

Go to Step 10

9
  1. Turn the ignition to OFF.
  2. Test the BN wire from fuse F11 to terminal 43 of connector C201, from terminal 62 of connector C202 to terminal 6 of connector C110, and from there to terminal 15 of the EBCM connector.
  3. Repair any short circuit found along this path.

Did you find and correct the condition?

--

System OK

--

10
  1. Turn the ignition switch to OFF.
  2. Install the scan tool.
  3. Clear all DTCs.
  4. Road test the vehicle.

Does DTC C0800 reset?

--

System OK

--

11
  1. Disconnect the EBCM connector from the EBCM.
  2. Turn the ignition to ON.
  3. Test for 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 13

Go to Step 12

12
  1. Turn the ignition switch to OFF.
  2. Test the OG 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 find and correct the condition?

--

System OK

--

13

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 17

Go to Step 14

14
  1. Turn the ignition switch to OFF.
  2. Inspect fuse EF5 in the engine fuse block.

Is the fuse open?

--

Go to Step 15

Go to Step 16

15

Replace fuse EF5.

Did you complete the replacement?

--

System OK

--

16
  1. Test circuit BN between terminal 15 of the EBCM connector to terminal 6 of connector C110 to terminal 62 of C202, to F11 in the instrument panel (I/P) fuse block.
  2. Test the PK wire from the I/P fuse block to terminal 4, IG1, of the ignition switch.
  3. Test the RD wire from terminal 2, B1, of the ignition switch to terminal 59 of connector C202 to terminal 4 of connector C105 at the engine fuse block.
  4. Repair the open in the wiring or possibly bad connector terminal, or defective ignition switch.

Did you find and correct the condition?

--

System OK

--

17
  1. Turn the ignition to OFF.
  2. Measure the resistance between ground and terminals 16 and 19 of the antilock brake system (ABS) harness EBCM connector.

Is the resistance equal to the specified value?

0 ohms

Go to Step 18

Go to Step 20

18

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

Is there a defective terminal?

--

Go to Step 19

Go to Step 21

19

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

Did you find and correct the condition?

--

System OK

--

20

Repair the defective ground connection.

Did you complete the repair?

--

System OK

--

21
  1. Install the scan tool.
  2. Clear all DTCs.
  3. Road test the vehicle.

Does DTC C0800 set?

--

Go to Step 23

Go to Step 22

22
  1. Test the wiring harness and connectors for causes of intermittent problems.
  2. Repair any intermittent problem found.

Did you find and correct the condition?

--

System OK

--

23

Replace the ABS unit.

Did you complete the replacement?

--

System OK

--