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

C0221 and C0225

The ignition is ON.

C0222 and C0226

    • The ignition is ON.
    • The rear wheel speed sensor signal is greater than 13 km/h (8 mph).

C0223 and C0227

    • The ignition is ON.
    • All of the wheel speed sensor signals are greater than 32 km/h (20 mph) when the brake is applied or 19 km/h (12 mph) when the brake is released.

Conditions for Setting the DTC

C0221 and C0225

The corresponding wheel speed sensor feedback voltage is detected as being high (greater than 3.33 volts) for 100 milliseconds or low (less than 0.039 volts) for 500 milliseconds.

C0222 and C0226

The corresponding wheel speed sensor signal is less than 6 km/h (4 mph) for 5 seconds (120 seconds in order to set multiple missing sensor DTCs).

C0223 and C0227

Either of the following conditions will set DTC C0223 or DTC C0227:

    • A sudden loss of the corresponding wheel speed sensor signal is detected for 15 milliseconds.
    • A sudden increase is detected in the corresponding wheel speed sensor signal at a rate greater than 8.8 km/h (5.5 mph) for 105 milliseconds.

Action Taken When the DTC Sets

    • The ABS and TRACTION OFF (if equipped with traction control) indicators are commanded on.
    • The ABS and Traction Control (if equipped) are disabled for as long as the malfunction is present. If the malfunction occurs 3 or more separate times, the ABS and Traction Control (if equipped) are disabled for the remainder of the ignition cycle (DTC C0223 and DTC C0227 only).
    • If DTC C0222 and DTC C0226 are both set or if DTC C0236 is set with either of these DTCs, the BRAKE indicator is also commanded ON and the DRP is disabled for as long as both malfunctions are present.

Conditions for Clearing the DTC

    • Repair the condition(s) responsible for setting the DTC.
    • Use a scan tool in order to clear the DTC.

Important: After the DTC is cleared and the ignition is ON, the ABS indicator may remain on until the EBCM completes a power-up self-test. This test concludes when the vehicle reaches a speed of greater than 13 km/h (8 mph) and the wheel speeds are verified by the EBCM.

Diagnostic Aids

Operating the vehicle on extremely rough terrain may set DTC C0223 or DTC C0227 even if the system is functioning properly.

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

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 circuit(s) for signs of water intrusion. Use the following procedure to help isolate the problem area:

  1. Spray the suspected area with a 5% salt water solution (two teaspoons of salt to 12 oz. of water).
  2. Drive the vehicle at a speed greater than 24 km/h (15 mph) for at least 30 seconds.

Replace the suspect harness if the DTC sets.

Inspect the terminal cavity of the wheel speed sensor for corrosion. Replace the wheel speed sensor if corrosion exists. Refer to Wheel Speed Sensor Replacement .

Step

Action

Value(s)

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

2

  1. Use a scan tool in order to clear the DTC(s).
  2. Operate the vehicle at a speed greater than the specified value.

Does the DTC set?

32 km/h (20 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. Use a DMM in order to measure the resistance of the wheel speed sensor.

Does the resistance measure within the specified range?

700-10,000 ohms

Go to Step 4

Go to Step 8

4

  1. Slowly spin the wheel by hand.
  2. Use a DMM in order to measure the AC voltage generated by the wheel speed sensor as the wheel spins.

Does the 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

Test the wheel speed sensor circuit for the following conditions:

    • 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 10

Go to Step 7

7

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 10

Go to Step 9

8

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

Did you complete the replacement?

--

Go to Step 10

--

9

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

Important: Perform the Tire Size Calibration procedure. Refer to Scan Tool Diagnostics

Did you complete the replacement?

--

Go to Step 10

--

10

  1. Use the scan tool in order to to clear the DTC.
  2. Operate the vehicle at a speed greater than the specified value.

Does the DTC set?

32 km/h (20 mph)

Go to Step 3

System OK