GM Service Manual Online
For 1990-2009 cars only

Circuit Description

As the wheel spins, the wheel speed sensor produces an AC signal. The EBCM uses the frequency of the AC signal to calculate the wheel speed.

Conditions for Running the DTC

C0035 C0040 C0045 C0050

The ignition is ON.

C0036 C0041 C0046 C0051

    • Vehicle speed is over 40 km/h (25 mph).
    • The brake pedal is not pressed.
    • The ABS is not active.

Conditions for Setting the DTC

C0035 C0040 C0045 C0050

One of the following conditions exists for 0.02 seconds:

    • A short to voltage - the wheel speed sensor signal circuit greater than 4.25 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 C0051

All of the following conditions exists for 10 ms:

    • The suspect wheel speed equals zero.
    • The other wheel speeds are greater than 40 km/h (25 mph) for 0.01 seconds.
    • The suspect wheel equals zero during drive off, and the other wheels are greater than 12 km/h (7.5 mph).
    • A short to ground - the wheel speed sensor signal circuit is shorted to ground.
    • A deviation of two wheel speeds at either side of the vehicle greater than 6 km/h (4 mph), or at the front axle greater than 10 km/h (6 mph) for a time period of 10 to 20 seconds.

Action Taken When the DTC Sets

If equipped, the following actions occur:

    • The EBCM disables the ABS/TCS for the duration of the ignition cycle.
    • The ABS indicator turns ON.
    • The Traction Off indicator turns ON.
    • The Red BRAKE Warning indicator could turn on.

Conditions for Clearing the DTC

    • The condition for the DTC is no longer present (the DTC is not current) and you used the scan tool Clear DTC function.
    • The EBCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

Diagnostic Aids

C0035 C0040 C0045 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 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 are thoroughly when completed.

C0036 C0041 C0046 C0051

Under the following conditions, 2 Wheel Speed Sensor Input is 0 DTCs are set:

    • The 2 suspect wheel speeds equal zero for 10-20 seconds.
    • The other wheel speeds are greater than 16 km/h (10 mph).
    • The other wheel speeds are within 11 km/h (7 mph) of each other.

Diagnose each wheel speed sensor individually.

C0036 C0041 C0046 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.

Test Description

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

  1. This step tests the wheel speed sensor for the proper resistance value.

  2. This step ensures that the wheel speed sensor generates the proper voltage.

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 the ABS Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - ABS

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 in General Information.
  2. Disconnect the wheel speed sensor connector.
  3. Measure the resistance across the wheel speed sensor.

Does the resistance measure within the specified range?

800-1600 ohms

Go to Step 4

Go to Step 8

4

  1. Spin the wheel.
  2. Measure the AC voltage across the wheel speed sensor.

Does the AC 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 in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 10

Go to Step 6

6

  1. Disconnect the EBCM harness connector.
  2. Install the J 39700 Universal Pinout Box using J 39700-530 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 Testing for Intermittent Conditions and Poor Connections and Wiring Repairs in Wiring Systems.

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 Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 10

Go to Step 9

8

Replace the wheel speed sensor. Refer to Front Wheel Bearing and Hub Replacement or Rear Wheel Bearing and Hub Replacement in Rear Suspension.

Did you complete the replacement?

--

Go to Step 10

--

9

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

Did you complete the repair?

--

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