GM Service Manual Online
For 1990-2009 cars only

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 alternating current (AC) voltage signal whose frequency is proportional to the wheel speed. The magnitude of this signal is directly related to wheel speed and the proximity of the wheel speed sensor to the toothed ring often referred to as the air gap.

Conditions for Running the DTC

This tests the intermittent left front wheel speed sensor circuit.

Conditions for Setting the DTC

    • The wheel speed sensor is intermittent shorted to the battery or ground.
    • There is a loose connection in the wheel speed sensor circuit.
    • There is a loose connection in the electronic brake control module (EBCM).
    • The EBCM is malfunctioning.

Action Taken When the DTC Sets

This is a critical operational fault. The antilock brake system (ABS) is disabled and the ABS warning lamp repeat intermittent turned ON, and OFF. The proportioning is operation.

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:

    • A short to ground or a short to voltage in the wheel speed sensor circuitry
    • An open or high resistance in the wheel speed sensor circuitry
    • A malfunctioning wheel speed sensor
    • A malfunctioning wheel speed sensor rotor
    • An internal EBCM malfunction

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

Step

Action

Values

Yes

No

Schematic Reference: Antilock Brake System Schematics

Connector End View Reference: Antilock Brake System Connector End Views

1

  1. Turn the ignition switch to OFF.
  2. Disconnect the EBCM harness connector from the EBCM.
  3. Use a digital voltmeter (DVM) to measure the resistance between terminals 14 and 25 of the connector on the EBCM harness.

Is the resistance within the specified value?

1.0-1.5 kohms

Go to Step 4

Go to Step 2

2

  1. Disconnect the harness from the left front wheel speed sensor.
  2. Use a DVM to measure the resistance between terminals 1 and 2 of the left front wheel speed sensor connector.

Is the resistance within the specified value?

1.0-1.5 kohms

Go to Step 4

Go to Step 3

3

Replace the wheel speed sensor.

Is the repair complete?

--

System OK

--

4

Use a DVM to measure the resistance between ground and terminal 14 of the EBCM connector.

Does the DVM show the specified value?

Go to Step 6

Go to Step 5

5

Repair the short to ground in circuit DK BLU.

Is the repair complete?

--

System OK

--

6

Use a DVM to measure the resistance between ground and terminal 25 of the EBCM connector.

Does the DVM show the specified value?

Go to Step 8

Go to Step 7

7

Repair the short to ground in circuit YEL.

Is the repair complete?

--

System OK

--

8

  1. Turn the ignition switch to ON.
  2. Use a DVM to measure the voltage between ground and terminal 14 of the EBCM connector.

Is the voltage within the specified value?

0 V

Go to Step 10

Go to Step 9

9

Repair the short to voltage in circuit DK BLU.

Is the repair complete?

--

System OK

--

10

Use a DVM to measure the voltage between ground and terminal 25 of the EBCM connector.

Is the voltage within the specified value?

0 V

Go to Step 12

Go to Step 11

11

Repair the short to voltage in circuit YEL.

Is the repair complete?

--

System OK

--

12

Replace the EBCM.

Is the repair complete?

--

System OK

--