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

### Circuit Description

As a toothed ring passes by the wheel speed sensor, changes in the electromagnetic field cause the wheel speed sensor to produce an AC voltage signal. The EBCM uses the frequency of the AC signal to calculate the wheel speed.

### Conditions for Running the DTC

• | No wheel speed sensor circuit hardware malfunctions are present.

• | The brake switch is OFF.

### Conditions for Setting the DTC

The EBCM detects a rapid variation in the wheel speed. The wheel speed changes by 16 km/h (10 mph) or more in 0.01 seconds. The change must occur 3 times with no more than 1 second between occurrences.

### Action Taken When the DTC Sets

• | The EBCM stores a malfunction DTC.

• | The EBCM disables the ABS and ETS.

• | The ABS warning indicator turns ON.

• | The TRAC OFF indicator turns ON.

### Conditions for Clearing the DTC

• | The condition responsible for setting the DTC no longer exists and the Scan Tool Clear DTCs function is used.

• | 100 drive cycles pass with no DTCs detected. A drive cycle consists of starting the vehicle, driving the vehicle over 16 km/h (10 mph), stopping and then turning the ignition OFF.

### Diagnostic Aids

Thoroughly inspect the wiring and the connectors. An incomplete inspection of the wiring and the connectors may result in a misdiagnosis, causing a part replacement with the reappearance of the malfunction.

The following are possible causes of the malfunction:

• | Poor connections

• | Broken wire insulation

• | A break in the wire inside the insulation

• | Loose or damaged toothed ring

• | Loose or damaged hub/bearing assembly

• | Loose or damaged wheel speed sensor

• | Loose or damaged CV joint

If an intermittent malfunction exists, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

### Test Description

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

1. This step tests the wheel speed sensor for the proper resistance value.

2. This step ensures that the wheel speed sensor generates the proper voltage.

3. This step tests whether the wheel speed sensor circuits are shorted together.

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

1. Install a scan tool.
2. Turn ON the ignition.
3. Drive the vehicle at a speed greater than 8 km/h (5 mph).
4. With a scan tool, observe all of the Wheel Speed parameters in the ABS data list.

Does the scan tool indicate the suspect wheel speed varies from the speeds of the other wheels?

--

Go to Step 3

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

3 | Inspect the following components for physical damage:

• | The wheel speed sensor

• | The wheel speed sensor harness

• | The wheel speed sensor harness connector

Did you find and correct the condition?

--

Go to Step 11

Go to Step 4

4 |

1. Disconnect the wheel speed sensor connector.
2. Measure the resistance across the wheel speed sensor.

Does the resistance measure within the specified range?

1040-1160ohms

Go to Step 5

Go to Step 9

5 |

1. By hand, spin the wheel as fast as possible.
2. Measure the AC voltage across the wheel speed sensor.

Does the AC voltage measure greater than the specified value?

100 mV

Go to Step 6

Go to Step 9

6 | Inspect for poor connections/terminal tension at the wheel speed sensor harness connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 7
7 |

1. Disconnect the EBCM harness connector.
2. Test for a short between the wheel speed sensor signal low and signal high circuits. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 11

Go to Step 8

8 | Inspect for poor connections/terminal tension at the EBCM harness connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 10
9 | Replace the wheel speed sensor. Refer to Front Wheel Speed Sensor Replacement . Did you complete the replacement? | -- | Go to Step 11 | --
10 | Replace the EBCM. Refer to Electronic Brake Control Module Replacement . Did you complete the replacement? | -- | Go to Step 11 | --
11 |

1. Use the scan tool in order to clear the DTCs.
2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

--

Go to Step 2

System OK