GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2004 🢒 GTO 🢒 DTC 🢒 DTC 28

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.
    • Vehicle speed of 12 km/h (8 mph) or more.

Conditions for Setting the DTC

The EBCM detects a wheel speed sensor frequency error.

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 malfunctioning wheel speed sensor
    • A malfunctioning wheel speed sensor ring
    • 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
    • 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 front wheel speed sensors for proper resistance value.

    2.

  2. This step tests the front wheel speed sensors for proper resistance value.

    3.

  3. This step tests the 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

Inspect the wheel speed sensors for damage.

Is a wheel speed sensor damaged?

--

Go to Step 10

Go to Step 4

4

Inspect the wheel speed sensor rings for damage.

Is a wheel speed sensor ring damaged?

--

Go to Step 11

Go to Step 5

5
  1. Disconnect each front wheel speed sensor jumper harness connector at the main wiring harness.
  2. Measure the resistance across the terminals of the front wheel speed sensor side of the jumper harness.

Does the resistance measure within the specified range?

1600-1800ohms

Go to Step 7

Go to Step 6

6
  1. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
  2. Disconnect each front wheel speed sensor connector at the wheel speed sensor.
  3. Measure the resistance across the front wheel speed sensor terminals.

Does the resistance measure within the specified range?

1600-1800ohms

Go to Step 12

Go to Step 10

7
  1. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
  2. Disconnect the rear wheel speed sensor connectors.
  3. Measure the resistance across the rear wheel speed sensor terminals.

Does the resistance measure within the specified range?

1444-1760ohms

Go to Step 8

Go to Step 10

8
  1. Disconnect the EBCM harness connector.
  2. Test the 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 14

Go to Step 9

9

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 14

Go to Step 13

10

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

Did you complete the replacement?

--

Go to Step 14

--

11

Replace the wheel speed sensor ring. Refer to Front Wheel Bearing and Hub Replacement in Front Suspension or Rear Axle Shaft Replacement in rear Drive Axle.

Did you complete the replacement?

--

Go to Step 14

--

12

Replace the front wheel speed sensor jumper harness. Refer to Front Wheel Speed Sensor Jumper Harness Replacement .

Did you complete the replacement?

--

Go to Step 14

--

13

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

Did you complete the replacement?

--

Go to Step 14

--

14
  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