No Communication with Electronic Brake Control Module. Chevrolet Joy 2008

For 1990-2009 cars

### Circuit Description

Battery voltage is supplied to the electronic brake control module (EBCM) through fuse F14 in the instrument panel (I/P) fuse block, to terminal 20 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. This step inspects for voltage at the ignition 1 source.

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

4. This step inspects for a defective ground connection.

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

Step | Action | Values | 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 | Measure the voltage at the battery. Does the voltage measure within the specified range? | 11-14 V | Go to Step 4 | Go to Step 3
3 | Charge or replace the battery as required. Did you find and correct the condition? | -- | System OK | --
4 | Inspect fuse EF2 in the engine fuse block. Is the fuse open? | -- | Go to Step 5 | Go to Step 9

5

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

Does the fuse blow?

--

Go to Step 7

Go to Step 6

6 | Inspect the antilock brake system (ABS) function. Did you complete the action? | -- | System OK | --

7

1. Turn the ignition to OFF.
2. Remove fuse EF2.
3. Disconnect the electronic brake control module (EBCM) connector.
4. Measure the resistance to ground at terminals 14 and 1.

Is the resistance equal to the specified value?

0 ohms

Go to Step 8

Go to Step 26

8 | Repair the short to ground in circuit between terminal 1 of the engine fuse block connector C104 and the EBCM connector. Did you complete the repair? | -- | System OK | --
9 | Inspect fuse Ef2 in the engine fuse block. Is the fuse open? | -- | Go to Step 10 | Go to Step 14

10

1. Replace fuse Ef2.
2. Turn the ignition to ON.

Does the fuse blow?

--

Go to Step 12

Go to Step 11

11 | Inspect the ABS function. Did you find and correct the condition? | -- | System OK | --

12

1. Turn the ignition to OFF.
2. Remove fuse Ef2.
3. Disconnect the EBCM connector.
4. Measure the resistance to ground at terminal 20.

Is the resistance equal to the specified value?

0 ohms

Go to Step 13

Go to Step 26

13

1. Test circuit between terminal of engine fuse block and terminal 2 of the ignition switch.
2. Test circuit from terminal of the ignition switch to fuse F14 in the instrument panel (I/P) fuse block.
3. Test circuit from fuse F14 in the I/P fuse block to terminal 20 of the EBCM connector.
4. Repair any short to ground found in the wiring or the ignition switch.

Did you find and correct the condition?

--

System OK

--

14 | Inspect fuse F14 in the I/P fuse block. Is the fuse open? | -- | Go to Step 15 | Go to Step 19

15

1. Replace fuse F14.
2. Turn the ignition to ON.

Does the fuse blow?

--

Go to Step 17

Go to Step 16

16 | Inspect the ABS function. Is the repair complete? | -- | System OK | --

17

1. Turn the ignition to OFF.
2. Remove fuse F14.
3. Disconnect the EBCM connector.
4. Measure the resistance to ground at terminal 20.

Is the resistance equal to the specified value?

0 ohms

Go to Step 18

Go to Step 26

18 | Repair the short to ground in circuit fuse F14 of the I/P fuse block and terminal 20 of the EBCM connector. Did you complete the repair? | -- | System OK | --

19

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 14, and between ground and terminal 1.

Does the voltage measure within the specified range?

11-14 V

Go to Step 21

Go to Step 20

20

1. Turn the ignition switch to OFF.
2. Trace the wires between terminals 14 and 1 of the EBCM connector to terminal 1 of connector C104 at the engine fuse block.
3. Repair the open in this circuit.

Did you complete the repair?

--

System OK

--

21 | Measure the voltage between ground and terminal 20 of the EBCM connector. Does the voltage measure within the specified range? | 11-14 V | Go to Step 23 | Go to Step 22

22

1. Turn the ignition switch to OFF.
2. Test circuit between terminal 20 of the EBCM connector to fuse F14 in the I/P fuse block.
3. Test circuit from fuse F14 of the I/P fuse block to terminal 4, IG1, of the ignition switch.
4. Test circuit from terminal 2, B1, of the ignition switch to terminal of the engine fuse block.
5. Repair the open in the wiring or possibly bad connector terminal, defective ignition switch, or blown fuse.

Did you find and correct the condition?

--

System OK

--

23

1. Turn the ignition to OFF.
2. Measure the resistance between ground and terminals 26 and 13 of the EBCM connector.

Is the resistance equal to the specified value?

0 ohms

Go to Step 24

Go to Step 27

24 | Test terminals 20, 26, 14, 1, and 13 of the EBCM connector. Is there a defective terminal? | -- | Go to Step 25 | Go to Step 26
25 | Repair the defective terminal or replace the connector or wiring harness as required. Did you complete the repair? | -- | System OK | --
26 | Replace the EBCM. Refer to Brake Pressure Modulator Valve Assembly Replacement . Did you complete the replacement? | -- | System OK | --
27 | Repair the defective ground connection. Did you complete the repair? | -- | System OK | --