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.

DTC Descriptors

This diagnostic procedure supports the following DTCs:

    • DTC C0035 Left Front Wheel Speed Sensor Circuit
    • DTC C0036 Left Front Wheel Speed Sensor Circuit Range/Performance
    • DTC C0037 Left Front Wheel Speed Sensor Circuit Low
    • DTC C0040 Right Front Wheel Speed Sensor Circuit
    • DTC C0041 Right Front Wheel Speed Sensor Circuit Range/Performance
    • DTC C0042 Right Front Wheel Speed Sensor Circuit Low
    • DTC C0045 Left Rear Wheel Speed Sensor Circuit
    • DTC C0046 Left Rear Wheel Speed Sensor Circuit Range/Performance
    • DTC C0047 Left Rear Wheel Speed Sensor Circuit Low
    • DTC C0050 Right Rear Wheel Speed Sensor Circuit
    • DTC C0051 Right Rear Wheel Speed Sensor Circuit Range/Performance
    • DTC C0052 Right Rear Wheel Speed Sensor Circuit Low

Conditions for Running the DTC

C0035, C0040, C0045, or C0050

The ignition is ON.

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

    • DTCs C0035, C0040, C0045, or C0050 are not set.
    • The brake pedal is not pressed.
    • The ABS is not active.

Conditions for Setting the DTC

C0035, C0040, C0045, or C0050

One of the following conditions exists for 0.02 seconds:

    • A short to voltage - the wheel speed sensor signal circuit and wheel speed sensor return circuit voltages are both greater than 4.25 volts.
    • A short to ground - the wheel speed sensor signal circuit and wheel speed sensor return circuit voltages are both less than 0.75 volts.
    • An open - the wheel speed sensor signal circuit voltage is greater than 4.25 volts and wheel speed sensor return circuit voltage is less than 0.75 volts.

C0036, C0041, C0046, or C0051

The EBCM detects a rapid variation in the wheel speed. The wheel speed changes by 16 km/h (10 mph) or more in 0.01 second. The change must occur 3 times with no more than 0.2 seconds between occurrences.

C0037, C0042, C0047, or C0052

All of the following conditions exists for 2.5 seconds:

    • The suspect wheel speed equals zero.
    • The other wheel speeds are greater than 8 km/h (5 mph).
    • The other wheel speeds are within 11 km/h (7 mph) of each other.

Action Taken When the DTC Sets

If equipped, the following actions occur:

    • The EBCM disables the ABS/TCS/VSES for the duration of the ignition cycle.
    • The DRP does not function optimally.
    • The ABS indicator turns ON.
    • The Traction Control indicator turns ON.
    • The DIC displays the Service Stability System message.

Conditions for Clearing the DTC

    • The condition for the DTC is no longer present and the DTC is cleared with a scan tool.
    • The EBCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

Diagnostic Aids

C0035, C0040, C0045, or C0050

If the customer comments that the ABS indicator is ON only during moist environmental conditions (rain, snow, vehicle wash, etc.), inspect the wheel speed sensor wiring for signs of water intrusion. If the DTC is not current, clear all DTCs and simulate the effects of water intrusion by using the following procedure:

  1. Spray the suspected area with a 5 percent saltwater solution. To create a 5 percent saltwater solution, add 2 teaspoons (9.9 ml) of salt to 354 ml (12 oz) of water.
  2. Test drive the vehicle over various road surfaces (bumps, turns, etc.) above 40 km/h (25 mph) for at least 30 seconds.
  3. If the DTC returns, replace the suspected wheel speed sensor or repair the wheel speed sensor wiring.
  4. Rinse the area thoroughly when completed.

C0036, C0041, C0046, or C0051

A possible cause of this DTC is electrical noise on the wheel speed sensor harness wiring. Electrical noise could result from the wheel speed sensor wires being routed to close to high energy ignition system components, such as spark plug wires.

C0037, C0042, C0047, or C0052

One of the following conditions may exist:

    • The wheel speed sensor inputs are shorted together.
    • Internal malfunction of the wheel speed sensor.
    • The other wheel speeds are within 11 km/h (7 mph) of each other.

Diagnose each wheel speed sensor individually.

Test Description

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

  1. This step measures the resistance of the wheel speed sensor in order to determine if the sensor has a valid resistance value.

  2. This step ensures that 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 Diagnostic System Check - Vehicle?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

  1. Install a scan tool.
  2. Turn ON the ignition.
  3. Set up the scan tool snap shot feature to trigger for this DTC.
  4. Drive the vehicle at a speed greater than the specified value.

Does the scan tool indicate that this wheel speed DTC set?

8 km/h (5 mph)

Go to Step 3

Go to Diagnostic Aids

3

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

Does the resistance measure within the specified range?

850-1350 ohms

Go to Step 4

Go to Step 8

4

  1. Spin the wheel.
  2. Measure the A/C voltage across the wheel speed sensor.

Does the A/C voltage measure greater than the specified value?

100 mV

Go to Step 5

Go to Step 8

5

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 .

Did you find and correct the condition?

--

Go to Step 10

Go to Step 6

6

  1. Disconnect the electronic brake control module (EBCM) harness connector.
  2. Install the J 39700 Universal Pinout Box using the J 39700-300 Cable Adapter to the EBCM harness connector only.
  3. Test the wheel speed sensor circuits for the following:
  4. • An open
    • A short to ground
    • A short to voltage
    • Shorted together

Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 10

Go to Step 7

7

Inspect for poor connections at the harness connector for the EBCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

--

Go to Step 10

Go to Step 9

8

Replace the wheel speed sensor. Refer to the appropriate procedure:

Did you complete the replacement?

--

Go to Step 10

--

9

Replace the EBCM. Refer to Control Module References for replacement, setup and programming.

Did you complete the replacement?

--

Go to Step 10

--

10

  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