GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2000 🢒 GL7 (Export) 🢒 DTC 🢒 DTC C1222 RF Wheel Speed Sensor Input Signal is 0

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
    • DTCs C1232-C1235 are not set.
    • The brake pedal is not pressed.
    • The ABS is not active.

Conditions for Setting the DTC

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
    • The EBCM disables the ABS for the duration of the ignition cycle.
    • The ABS indicator turns ON.

Conditions for Clearing the DTC
    • The condition for the DTC is no longer present and the DTC is cleared with a scan tool.
    • The electronic brake control module (EBCM) automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.

Diagnostic Aids

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

    • The 2 suspect wheel speeds equal zero for 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.

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.

  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

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 Testing for Intermittent Conditions and Poor Connections in Wiring Systems

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?

850-1350 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 the J 39700-99 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 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 Front Wheel Bearing and Hub Replacement in Front Suspension or Rear Wheel Bearing and Hub Replacement in Rear Suspension.

Did you complete the repair?

--

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