GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The electronic brake control module (EBCM) provides a common supply voltage to each digital front wheel speed sensor. As the front wheels spin, each wheel speed sensor produces a digital square wave signal. The EBCM uses the frequency of the wheel speed sensor signal to determine wheel speed.

Conditions for Running the DTC

Both of the conditions listed below may be required to set the DTC.

    • The ignition is ON.
    • The vehicles achieves a speed greater than 40 km/h (25 mph).

Conditions for Setting the DTC

Any of the following conditions may cause this DTC to set.

    • The EBCM detects an open or shorted wheel speed sensor for 200 milliseconds.
    • The EBCM detects a missing wheel speed sensor signal for 1 second. If more than one absent wheel speed sensor signal is detected, the condition must be present for 20 seconds to set DTCs.
    • The EBCM detects an erratic wheel speed sensor signal for 40 continuous or cumulative milliseconds.
    • The supply voltage to the front wheel speed sensors is detected as being at least 5 volts less than the monitored ignition voltage.

Action taken when the DTC sets

If equipped, the following actions occur.

    • The EBCM disables the ABS.
    • The EBCM disables the TCS.
    • The EBCM disables DRP if all wheel speed inputs have failed.
    • The ABS indicator turns ON.
    • The ABS fault message is displayed.
    • The traction fault message is displayed.
    • The brake warning indicator turns ON, if DRP is disabled.
    • The brakes message is displayed.
    • An ECE 13 response occurs. Refer to ABS Description and Operation for a complete description of ECE 13.

Conditions for Clearing the DTC

The Conditions for Setting the DTC are no longer present and you use the scan tool Clear DTCs function.

Diagnostic Aids

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

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 circuits for signs of water intrusion. Use the following procedure in order to help isolate the problem area:

  1. Spray the suspected area with a 5 percent salt water solution.
  2. Drive the vehicle at a speed greater than 19 km/h (12 mph) for at least 30 seconds.

Repair or replace the suspect harness if the DTC sets.

Test Description

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

  1. If the DTC sets when the vehicle is not moving, the EBCM is detecting an open or shorted wheel speed sensor or wheel speed sensor circuit.

  2. A short to ground in the right front wheel speed sensor supply voltage circuit appears electrically the same to the EBCM as a short to ground in the left front wheel speed sensor supply voltage circuit. Therefore, a short to ground in either circuit sets DTC C0035 and each circuit must be tested.

  3. The front wheel speed sensors produce a high resolution signal. Therefore, the slightest rotation of the wheel causes the signal to toggle from high to low.

Step

Action

Values

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. Use a scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Setting the DTC as specified in the supporting text.

Does the DTC set?

--

Go to Step 3

Go to Diagnostic Aids

3

  1. Turn OFF the ignition for at least 5 seconds.
  2. Turn ON the ignition.
  3. Use the scan tool to display Current DTCs.

Is DTC C0035 set as a current DTC?

--

Go to Step 4

Go to Step 12

4

  1. Turn OFF the ignition.
  2. Disconnect the electronic brake control module (EBCM) harness connector.
  3. Use a DMM to measure the resistance between the left front wheel speed sensor voltage supply circuit and a good ground.

Does the resistance measure less than the specified value?

45 ohms

Go to Step 6

Go to Step 5

5

Use a DMM to measure the resistance between the right front wheel speed sensor voltage supply circuit and a good ground.

Does the resistance measure less than the specified value?

45 ohms

Go to Step 6

Go to Step 9

6

  1. Disconnect the wheel speed sensor corresponding with the supply voltage circuit that showed a resistance level below specification.
  2. Use a DMM to again measure the resistance between the supply voltage circuit that measured low resistance and a good ground.

Does the resistance measure less than the specified value?

OL

Go to Step 8

Go to Step 7

7

Replace the wheel speed sensor corresponding with the supply voltage circuit that showed a resistance level below specification before the sensor was disconnected. Refer to Wheel Hub/Speed Sensor Replacement in Front Suspension.

Did you complete the replacement?

--

Go to Step 17

--

8

Repair the short to ground in the corresponding wheel speed sensor supply voltage circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 17

--

9

  1. Disconnect the left front wheel speed sensor harness connector.
  2. Test the left front wheel speed sensor signal circuit for an open or a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 17

Go to Step 11

10

Test the left front wheel speed sensor supply voltage circuit for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 17

Go to Step 11

11

  1. Reconnect the wheel speed sensor harness connector.
  2. At the EBCM harness connector, use a fused jumper wire to connect the left front wheel speed sensor supply voltage circuit to battery positive voltage.
  3. Set-up the DMM to measure current flow (mA/A).
  4. Connect the positive lead of the DMM to the left front wheel speed sensor signal circuit at the EBCM harness connector.
  5. Connect the negative lead of the DMM to ground.

Does the amperage measure within the specified range?

4 mA-16 mA

Go to Step 15

Go to Step 13

12

  1. Turn OFF the ignition.
  2. Disconnect the EBCM harness connector.
  3. Raise the vehicle so that the left front wheel is 2 cm (1 inch) off of the floor. Refer to Lifting and Jacking the Vehicle in General Information.
  4. At the EBCM harness connector, use a fused jumper wire to connect the left front wheel speed sensor supply voltage circuit to battery positive voltage.
  5. Set-up the DMM to measure current flow (mA/A).
  6. Connect the positive lead of the DMM to the left front wheel speed sensor signal circuit at the EBCM harness connector.
  7. Connect the negative lead of the DMM to ground.
  8. Slowly rotate the left front wheel by hand while observing the DMM.

Does the amperage toggle from lower measurement to higher measurement within the specified ranges?

Low signal: 4 mA-8 mA

High signal: 12 mA-16 mA

Go to Step 15

Go to Step 13

13

Inspect for poor connections at the harness connector of the left front 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 17

Go to Step 14

14

Replace the wheel speed sensor. Refer to Wheel Hub/Speed Sensor Replacement in Front Suspension.

Did you complete the replacement?

--

Go to Step 17

--

15

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 17

Go to Step 16

16

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

Did you complete the replacement?

--

Go to Step 17

--

17

  1. Reconnect all electrical components.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

--

Go to Step 3

System OK