For 1990-2009 cars
ABS Components
Wheel Speed Sensors

### Circuit Description

The wheel speed sensor generates an AC signal. The signal is produced when a toothed ring passes the wheel speed sensor. The frequency of the AC signal is proportional to the wheel speed. The EBCM uses the frequency of the signal in order to calculate the wheel speed.

### Conditions for Running the DTC

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

• | The brake switch is OFF.

• | The vehicle is not in an ABS event.

### Conditions for Setting the DTC

• | The change in the wheel speed is greater than 13.8 km/h (8.5 mph) in 0.01 seconds

• | The change in wheel speed must occur three times in less than 0.2 seconds

### Action Taken When the DTC Sets

• | The EBCM disables the ABS.

• | The ABS warning 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

The following conditions may cause an intermittent malfunction:

• | A poor connection

• | Rubbed-through wire insulation

• | A broken wire inside the insulation

• | Backed out terminals

• | Improper mating

• | Broken locks

• | Improperly formed or damaged terminals

• | Poor terminal-to-wiring connections

• | Physical damage to the wiring harness

Resistance of the wheel speed sensor will increase with an increase in sensor temperature.

Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems if an intermittent malfunction exists.

### 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?

1000-2000 ohms

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 | 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