GM Service Manual Online
For 1990-2009 cars only

Circuit Description

As the wheel spins, the wheel speed sensor produces an 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

C0035, C0040, C0045 and C0050

The ignition is ON.

C0036, C0037, C0041, C0042, C0046, C0047, C0051 and C0052

    • The ignition is ON.
    • The vehicle speed is greater than 20 km/h (13 mph).

Conditions for Setting the DTC

C0035, C0040, C0045 and C0050

The the EBCM detects an open or shorted wheel speed sensor or wheel speed sensor circuit.

C0036, C0041, C0046 and C0051

The EBCM detects an erratic signal from the corresponding wheel speed sensor.

C0037, C0042, C0047 and C0052

The corresponding wheel speed sensor signal is 0 km/h (0 mph).

Action Taken When the DTC Sets

If equipped, the following actions occur.

    • The EBCM disables ABS/TCS.
    • The ABS indicator turns ON.
    • The traction off indicator turns ON.

Conditions for Clearing the DTC

The conditions for setting the DTC are no longer present and you use the scan tool Clear DTCs function.

Diagnostic Aids

Thoroughly inspect connections or circuitry that may cause an intermittent malfunction. Refer to Testing for Intermittent Conditions and Poor Connections , Connector Repairs , Testing for Electrical Intermittents and to Wiring Repairs in Wiring Systems.

If the customer's concern is that the ABS indicator is on only during humid conditions such as rain, snow or vehicle wash, thoroughly inspect the wheel speed sensor circuits for signs of water intrusion. Use the following procedure in order to help isolate the problem area:

  1. Spray the suspected area with a 5 percent salt water solution.
  2. Drive the vehicle at a speed greater than 19 km/h (12 mph) for at least 30 seconds.

Repair or replace the suspect harness if the DTC sets.

Test Description

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

  1. This step tests for the correct bearing play. Excessive bearing play can cause wheel speed sensor air gap to exceed specification. Wheel speed sensor air gap must be reinspected after a repair is made to correct excessive bearing play.

  2. Measure the resistance value of the wheel speed sensor in order to determine if the sensor has a valid resistance value.

  3. Ensures the wheel speed sensor is generating a valid AC voltage output.

Step

Action

Values

Yes

No

Schematic Reference: Antilock Brake System Schematics

1

Did you perform the ABS Diagnostic System Check?

--

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 at a speed greater than the specified value.

Does the DTC set?

20 km/h (13 mph)

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. Verify that the wheel bearing play is within specifications. Refer to Wheel Bearing Adjustment in Front Suspension or Wheel Bearing Adjustment in Rear Drive Axle.

Did you find and correct the condition?

--

Go to Step 12

Go to Step 4

4

Inspect the wheel speed sensor in order to ensure the sensor is installed and retained properly for proper air gap. Refer to Front Wheel Speed Sensor Replacement or Rear Wheel Speed Sensor Replacement .

Did you find and correct the condition?

--

Go to Step 12

Go to Step 5

5

  1. Disconnect the wheel speed sensor harness connector.
  2. Use a DMM in order to measure the resistance across the wheel speed sensor.

Does the resistance measure within the specified range?

1800-2200 ohms

Go to Step 6

Go to Step 8

6

Slowly spin the wheel by hand while using a DMM to measure the AC voltage across the wheel speed sensor.

Does the AC voltage measure greater than the specified value?

800 mV

Go to Step 7

Go to Step 8

7

Inspect for poor connections at the harness connector of the wheel speed sensor. 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 12

Go to Step  9

8

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 12

--

9

Test the wheel speed sensor circuits for the following:

    • 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 12

Go to Step  10

10

Inspect for poor connections at the harness connector of 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 12

Go to Step  11

11

Important: Following EBCM replacement, use the scan tool to perform the Tire Size/Wheel Base Calibration procedure.

Replace the EBCM. Refer to Electronic Brake Control Module Replacement .

Did you complete the replacement?

--

Go to Step 12

--

12

  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 set?

--

Go to Step 3

System OK