For 1990-2009 cars
ABS Components
Antilock Brake System Schematics
Handling ESD Sensitive Parts Notice

### Circuit Description

The EBCM interfaces with a scan tool through terminal 4 via to Data Link Connector (DLC) terminal 7. A properly set scan tool connected to the DLC can retrieve ABS diagnostic information like Diagnostic Trouble Codes (DTCs) and perform ABS device control for testing purposes.

### Diagnostic Aids

Inspect for the following list of items when diagnosing this part of the Antilock Brake System (ABS):

• | An open ECU-IG fuse

• | An open ABS fuse

• | A clean tight G103

The EBCM will not interface with a scan tool if these circuits have excessive resistance:

• | The serial data line

• | The ignition power circuit

• | G103

Ensure that these circuits are in good condition and that no excessive resistance occurs. Also inspect the EBCM electrical connector for poor connector terminal contact.

### Test Description

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

1. This test determines if the scan tool can communicate with any other modules on the Class 2 serial data line.

2. Tests for a short to ground in the ignition positive voltage circuit.

3. Tests the EBCM ground circuit for an open or high resistance.

4. Tests the ignition positive voltage circuit for an open or high resistance.

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform A Diagnostic System Check - ABS? | -- | Go to Step 2 | Go to Diagnostic System Check - ABS
2 |

1. Turn OFF the ignition.
2. Install a scan tool.
3. Turn ON the ignition, with the engine OFF.
4. Attempt to establish communication with other modules on the serial data line, such as the PCM.

Does the scan tool communicate with any other modules on the serial data line?

--

Go to Step 3

Go to Scan Tool Does Not Communicate with Components in Data Link Communications

3 |

1. Turn OFF the ignition.
2. Inspect the ECU-IGN Fuse (10A).

Is the fuse open?

--

Go to Step 4

Go to Step 5

4 |

1. Turn OFF the ignition.
2. Remove the ECU-IGN Fuse (10A) from Junction Block 2.
3. Test the Ignition Positive Voltage circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Diagnostic System Check - ABS

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

5 | Inspect the EBCM ground circuit, making sure that the ground is clean and torqued to the proper specification. Refer to Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Diagnostic System Check - ABS | Go to Step 6
6 |

1. Turn OFF the ignition.
2. Test the EBCM ground circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Diagnostic System Check - ABS

Go to Step 7

7 | Test the Ignition Positive Voltage circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Diagnostic System Check - ABS | Go to Step 8
8 | Inspect for poor connections at the harness connector of the EBCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Diagnostic System Check - ABS | Go to Step 9
9 | Replace the Brake Modulator Assembly. Refer to Brake Pressure Modulator Valve Assembly Replacement . Did you complete the replacement? | -- | Go to Diagnostic System Check - ABS | --