GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2000 🢒 GMC K Pickup - 4WD 🢒 Brakes 🢒 Antilock Brake System 🢒 DTC C0226 or C026 LF Wheel Speed Signal Missing

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

Conditions for Setting the DTC

The left front 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).

Action Taken When the DTC Sets
    • The ABS indicator is commanded ON.
    • The ABS is disabled for as long as the malfunction is present.

If DTC C0222 and DTC C0226 are both set in the EBCM memory, 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 remains 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

The malfunction must be present during diagnosis in order to prevent unnecessary parts replacement.

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?

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. Spin the wheel.
  3. Measure the AC voltage across the wheel speed sensor.

Does the AC voltage measure greater than the specified value?

100 mV

Go to Step 4

Go to Step 5

4

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 7

Go to Step 6

5

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

Did you complete the replacement?

--

Go to Step 7

--

6

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 7

--

7
  1. Use a scan tool in order to clear the DTC.
  2. Operate the vehicle at a speed greater than the specified value.

Does the DTC set?

13 km/h (8 mph)

Go to Step 3

System OK