GM Service Manual Online
For 1990-2009 cars only

Circuit Description

As the wheel spins, the wheel speed sensor produces an alternating current (AC) signal. The electronic brake control module (EBCM) uses the frequency of the AC signal to calculate the wheel speed.

Conditions for Running the DTC

The ignition is in the ON position.

Conditions for Setting the DTC

The EBCM detects a short, open or high resistance in the rear wheel speed sensor circuits.

Action Taken When the DTC Sets

The following actions occur:

    • The EBCM disables the antilock brake system (ABS) and traction control system for the duration of the ignition cycle.
    • The ABS and TRAC OFF indicators turn 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.

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 rear wheel speed sensor circuitry
    • An open or high resistance in the rear wheel speed sensor circuitry
    • A malfunctioning rear wheel speed sensor
    • An internal EBCM malfunction

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 rear wheel speed sensor circuits for a short, open or high resistance.

Step

Action

Value(s)

Yes

No

Schematic Reference: Antilock Brake System Schematics

Connector End View Reference: Antilock Brake System Connector End Views

1

Did you perform A Diagnostic System Check - ABS?

--

Go to Step 2

Go to Diagnostic System Check - ABS

2

  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 3

Go to Diagnostic Aids

3

  1. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
  2. Disconnect the rear wheel speed sensor connector.
  3. Measure the resistance across the rear wheel speed sensor terminals.

Does the resistance measure within the specified range?

1440-1760ohms

Go to Step 4

Go to Step 6

4

  1. Disconnect the EBCM harness connector.
  2. Test the rear wheel speed sensor circuits for the following:
  3. • An open
    • A short to ground
    • A short to voltage
    • Shorted together

Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 8

Go to Step 5

5

Inspect for poor connections at the harness connector for 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 Step 8

Go to Step 7

6

Replace the rear wheel speed sensor. Refer to Rear Wheel Speed Sensor Replacement .

Did you complete the replacement?

--

Go to Step 8

--

7

Replace the electronic brake control module (EBCM). Refer to Electronic Brake Control Module Replacement .

Did you complete the replacement?

--

Go to Step 8

--

8

  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