For 1990-2009 cars
ABS Components
Antilock Brake System Schematics

### Circuit Description

This symptom table checks the state of the ABS indicator to identify a situation in which the driver could not be warned of a system malfunction by the ABS indicator. The EBTCM provides a ground through the ABS indicator control circuit to turn the ABS indicator on. If the control circuit is open or if the control circuit is shorted to voltage the ABS indicator will always be off. The EBTCM provides a redundant control circuit on the 4-pin connector C2, terminal 4 in the event that the 25-pin harness connector C1 becomes disconnected from the EBTCM. If this occurs, the ABS indicator will be turned on by a ground provided on the 4-pin connector C2, terminal 4.

### Diagnostic Aids

The following can cause an intermittent malfunction:

• | A poor connection can cause an intermittent malfunction.

• | Rubbed through wire insulation can cause an intermittent malfunction.

• | A wire that is broken inside the insulation can cause an intermittent malfunction.

The ABS Indicator Lamp Test function of the scan tool may be used to command the indicator while looking for an intermittent malfunction in the ABS indicator circuitry.

Check for the following in any circuit suspected of causing an intermittent malfunction:

• | Check for backed out terminals.

• | Check for improper mating.

• | Check for broken locks.

• | Check for improperly formed terminals.

• | Check for damaged terminals.

• | Check for poor terminal to wiring connections.

• | Check for physical damage to the wiring harness.

### Test Description

The number(s) below refer to the step numbers on the diagnostic table.

1. Running the scan tool Lamp Test will determine if the EBTCM can turn the indicator on and off.

2. If both EBTCM connectors C1 and C2 are not properly connected, the ABS indicator will be inoperative.

3. If other indicators in the instrument panel are not operating properly, there may be a concern with the instrument panel circuitry.

4. With terminal 1 of the EBTCM connector C1 grounded, the ABS indicator should come on.

5. This step checks for an open in the ABS indicator circuit.

6. This step checks for a short to voltage in the ABS indicator circuit.

#### ABS Indicator Off No DTC Set

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Was the Diagnostic System Check performed? | -- | Go to Step 2 | Go to A Diagnostic System Check
2 |

1. Turn the ignition switch to the OFF position.
2. Install a scan tool.
3. Turn the ignition switch to the RUN position with the engine off.
4. Use the scan tool to select Special Functions.
5. Select and run ABS Indicator Lamp Test in Special Functions.

Was the test completed successfully?

--

Go to Step 6

Go to Step 3

3 |

1. Turn the ignition switch to the OFF position.
2. Remove the scan tool.
3. Turn the ignition switch to the RUN position with the engine off.

Does the ABS indicator turn on then turn off?

--

Go to Step 15

Go to Step 4

4 |

1. Turn the ignition switch to the OFF position.
2. Check that the 25-way EBTCM harness connector is properly retained to the EBTCM.
3. Check that the 4-way EBTCM harness connector is properly retained to the EBTCM.
4. Turn the ignition switch to the RUN position with the engine off.

Does the ABS indicator turn on then turn off?

--

Go to A Diagnostic System Check

Go to Step 5

5 |

1. Turn the ignition switch to the OFF position.
2. Turn the ignition switch to the RUN position with the engine off.
3. Observe the BRAKE indicator and observe the TC indicator.

Did the BRAKE indicator and the TC indicator turn on then turn off?

--

Go to Step 8

Go to A Diagnostic System Check - Instrument Cluster in Instrument Panel, Gages and Console for diagnosis

6 |

1. Turn the ignition switch to the OFF position.
2. Inspect the 25-way EBTCM connector C1, terminal 1 and inspect the 4-way EBTCM connector C2, terminal 4 for the following signs:

• | Inspect for signs of damage.

• | Inspect for signs of poor terminal contact.

• | Inspect for signs of terminal corrosion.

3. Inspect the remaining terminals of the 25-way EBTCM connector C1, and inspect the 4-way EBTCM connector C2 for the following signs:

• | Inspect for signs of damage.

• | Inspect for signs of poor terminal contact.

• | Inspect for signs of terminal corrosion.

Are the following signs evident:

• | Is poor terminal contact evident?

• | Is corrosion evident?

• | Is damaged terminal(s) evident?

--

Go to Step 13

Go to Step 7

7 |

1. Reconnect the 25-way EBTCM harness connector C1.
2. Reconnect the 4-way EBTCM harness connector C2 if previously disconnected.
3. Turn the ignition switch to the RUN position with the engine off.

Does the ABS indicator turn on and then turn off?

--

Go to Step 15

Go to Step 14

8 |

1. Turn the ignition switch to the OFF position.
2. Disconnect the 25-way EBTCM connector C1.
3. Install the J 39700 Universal Breakout Box with the J 39700-250 Cable Adapter to the EBTCM harness only.
4. Connect a fused jumper wire, with a 3A fuse between the J 39700 terminal 1 and ground.
5. Turn the ignition switch to the RUN position with the engine off.

Does the ABS indicator turn on?

--

Go to Step 6

Go to Step 9

9 |

1. Turn the ignition switch to the OFF position.
2. Remove the jumper wire.
3. Disconnect the instrument panel connector.
4. Use a J 39200 DMM to measure the resistance between the J 39700 terminal 1 and the instrument panel harness connector terminal 1.

Is the resistance within the specified range?

0-2 ohms

Go to Step 10

Go to Step 11

10 |

1. Turn the ignition switch to the RUN position with the engine off.
2. Use a J 39200 DMM to measure the voltage between J 39700 terminal 1 and ground.

Is the voltage within the specified range?

0-2 V

Go to A Diagnostic System Check - Instrument Cluster in Instrument Panel, Gages and Console for diagnosis

Go to Step 12

11 | Repair an open or a high resistance in the ABS indicator circuit. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to A Diagnostic System Check | --
12 | Repair a short to voltage in the ABS indicator circuit. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to A Diagnostic System Check | --
13 |

1. Repair the 25-way EBTCM connector C1.
2. Repair the 4-way EBTCM connector C2 if necessary. Refer to Connector Repairs in Wiring Systems.

Is the repair complete?

--

Go to A Diagnostic System Check

--

14 | Replace the EBTCM. Refer to EBTCM Replacement . Is the repair complete? | -- | Go to A Diagnostic System Check | --
15 | The malfunction is intermittent or the malfunction is not present at this time. Refer to Diagnostic Aids on the facing page for more information. Is the diagnosis complete? | -- | Go to A Diagnostic System Check | --