GM Service Manual Online
For 1990-2009 cars only

DTC C0226 or C026 LF Wheel Speed Signal Missing 310 ABS

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

    • Ignition switch is in the RUN position.
    • The rear speed sensor signal is greater than 13 km/h (8 mph).

Conditions for Setting the DTC

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

Action Taken When the DTC Sets

    • The ABS indicator lamp turns on.
    • The ABS disables for as long as the malfunction is present.
    • 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.

Conditions for Clearing the DTC

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

Diagnostic Aids

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

Step

Action

Value(s)

Yes

No

Schematic References: 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 of a speed greater than the specified value.

Does the DTC set?

13 km/h (8 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 across the wheel speed sensor.

Does the resistance measure within the specified range?

700-10000 ohms

Go to Step 4

Go to Step 8

4

  1. Spin the wheel by hand as fast as possible.
  2. Use a DMM in order to measure the AC voltage generated by 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

Test the wheel speed sensor circuits for the following:

  1. An open
  2. A short to ground
  3. A short to voltage
  4. 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 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 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

Important: Perform the tire size calibration in Scan Tool Diagnostics.

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

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

DTC C0226 or C026 LF Wheel Speed Signal Missing 325 ABS

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

    • Ignition switch is in the RUN position.
    • The rear speed sensor signal is greater than 13 km/h (8 mph).

Conditions for Setting the DTC

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

Action Taken When the DTC Sets

    • The ABS indicator lamp turns on.
    • The ABS disables for as long as the malfunction is present.
    • 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.
    • After the DTC is cleared and the ignition is ON, the ABS indicator will 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

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

Step

Action

Value(s)

Yes

No

Schematic References: 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 of a speed greater than the specified value.

Does the DTC set?

13 km/h (8 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 across the wheel speed sensor.

Does the resistance measure within the specified range?

700-10000 ohms

Go to Step 4

Go to Step 8

4

  1. Spin the wheel by hand as fast as possible.
  2. Use a DMM in order to measure the AC voltage generated by 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

Test the wheel speed sensor circuits for the following:

  1. An open
  2. A short to ground
  3. A short to voltage
  4. 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 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 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

Important: Perform the tire size calibration in Scan Tool Diagnostics.

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

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