GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The vehicle stability enhancement system (VSES) is activated by the EBCM calculating the desired yaw rate and comparing it to the actual yaw rate input. The desired yaw rate is calculated from measured steering wheel position, vehicle speed, and lateral acceleration. The difference between the desired yaw rate and actual yaw rate is the yaw rate error, which is a measurement of oversteer or understeer. If the yaw rate error becomes too large, the EBCM will attempt to correct the vehicle's yaw motion by applying differential braking to the wheels.

To correct for oversteer, differential braking is used on the left front or right front wheel brake. To correct for understeer, differential braking is used on the left rear or right rear wheel brake.

Conditions for Running the DTC

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

Conditions for Setting the DTC

The EBCM performs different tests to detect a DTC condition. A malfunction is detected when the yaw rate sensor signal input voltage is less than 0.225 volts or greater than 4.775 volts for more than 100 milliseconds.

Action Taken When the DTC Sets

If equipped, the following actions occur:

    • The EBCM disables the TCS/VSES for the duration of the ignition cycle.
    • A malfunction DTC is set.
    • The ANTI-LOCK indicator turns ON.
    • The TRAC Off indicator turns ON.
    • The PCS indicator turns ON.

Conditions for Clearing the DTC

    • Using a scan tool
    • The DTC will clear after 100 consecutive ignition cycles if the condition for the malfunction is no longer present.

Diagnostic Aids

The following conditions may cause a malfunction:

    • Open in the yaw rate signal circuit
    • Short to ground in the yaw rate signal circuit
    • Short to voltage in the yaw rate signal circuit
    • Open in the yaw rate ground circuit
    • Open in ignition voltage circuit
    • Malfunctioning vehicle yaw/lateral accelerometer sensor
    • Malfunctioning EBCM

Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

  1. Tests for specified voltage on the yaw rate signal circuit.

  2. Checks the voltage between the ignition and ground circuit for a specified value.

  3. Checks the voltage between the ignition and ground circuit for a specified value.

  4. Checks to see if voltage was above specified voltage.

  5. Checks to see if voltage was below specified voltage.

  6. Checks to see if EBCM 5 volt reference signal is within specified limit.

  7. Checks to see if voltage was above specified voltage.

  8. Checks to see if resistance of ground circuit is less than 5 ohms.

  9. Tests for a short to voltage on the 5 volt reference circuit.

  10. Tests for a short to ground, a high resistance, or an open in the 5 volt reference circuit.

  11. Tests for a short to voltage in the yaw rate signal circuit.

  12. Tests for a short to ground, a high resistance, or an open in the yaw rate signal circuit.

  13. Tests for a high resistance or an open in the ground circuit.

  14. Checks the EBCM connector for poor connections.

  15. Checks the yaw/lateral accelerometer sensor connector for poor connections.

Step

Action

Value(s)

Yes

No

Schematic Reference: Antilock Brake System Schematics

1

Did you perform the ABS Diagnostic System Check?

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Go to Step 2

Go to Diagnostic System Check - ABS

2

  1. Turn OFF the ignition.
  2. Disconnect the EBCM.
  3. Install the J 39700 universal pinout box with the J 39700-530 cable adapter between the EBCM and the EBCM harness connector.
  4. Turn ON the ignition, with the engine OFF.
  5. Using the DMM, measure the voltage between pin 26 and pin 15 of the J 39700 universal pinout box.

Is the voltage within the specified value?

0.225-4.775 V

Go to Diagnostic Aids

Go to Step 3

3

  1. Turn OFF the ignition.
  2. Disconnect the yaw/lateral accelerometer sensor.
  3. Turn ON the ignition, with the engine OFF.
  4. Using the DMM, measure the voltage between the ignition and ground circuits of the yaw/lateral accelerometer sensor.

Is the voltage in the specified value?

B+

Go to Step 5

Go to Step 4

4

Test the ignition circuit of the yaw/lateral accelerometer sensor for high resistance or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 18

Go to Power Distribution Schematics in Wiring Systems

5

  1. Reconnect the yaw/lateral accelerometer sensor.
  2. Using the DMM, measure the voltage between pin 26 and pin 15 of the J 39700 universal pinout box.

Is the voltage less than the specified value?

4.775 V

Go to Step 6

Go to Step 13

6

Using the DMM, measure the voltage between pin 26 and pin 15 of the J 39700 universal pinout box.

Is the voltage greater than the specified value?

0.225 V

Go to Step 7

Go to Step 12

7

Using a DMM, measure the voltage between the 5 volt reference circuit pin 16 and the ground circuit pin 15 of the J 39700 universal pinout box.

Does the voltage measure below the specified value?

2 V

Go to Step 11

Go to Step 8

8

Using a DMM, measure the voltage between the 5 volt reference circuit pin 16 and ground pin 15 of the J 39700 universal pinout box.

Does the voltage measure above the specified value?

3 V

Go to Step 10

Go to Step 9

9

  1. Turn OFF the engine.
  2. Disconnect the negative battery cable.
  3. Measure the resistance from the ground circuit of the yaw/lateral accelerometer sensor to a good ground.

Does the resistance measure less than the specified value?

5 ohms

Go to Step 16

Go to Step 14

10

Test the 5 volt reference circuit of the yaw/lateral accelerometer sensor for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 19

Go to Step 15

11

Test the 5 volt reference circuit of the yaw/lateral accelerometer sensor for a short to ground, a high resistance, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 19

Go to Step 12

12

Test the yaw rate signal circuit of the yaw/lateral accelerometer sensor for a short to ground, a high resistance, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 19

Go to Step 15

13

Test the yaw rate signal circuit of the yaw/lateral accelerometer sensor for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 19

Go to Step 15

14

  1. Disconnect the EBCM.
  2. Test the ground circuit of the yaw/lateral accelerometer sensor for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 19

Go to Step 15

15

Inspect for poor connections at the harness connector of the yaw/lateral accelerometer 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 19

Go to Step 17

16

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 19

Go to Step 18

17

Replace the vehicle yaw/lateral accelerometer sensor. Refer to Vehicle Yaw Sensor with Vehicle Lateral Accelerometer Replacement .

Did you complete the replacement?

--

Go to Step 19

--

18

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

Did you complete the replacement?

--

Go to Step 19

--

19

  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