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For 1990-2009 cars only
Makes 🢒 HUMMER 🢒 2007 🢒 H2 🢒 Driver Information and Entertainment 🢒 Cellular, Entertainment, and Navigation 🢒 DTC C0191

Circuit Description

The electronic brake control module (EBCM) provides power 5-volt reference to the longitudinal accelerometer. The longitudinal accelerometer converts the change in vehicle motion, or inertia, into a voltage signal. This signal is sent to the EBCM.

The voltage signal ranges, from 2.4-2.6 volts at zero speed change, constant motion, or stationary. The longitudinal accelerometer voltage signal drops when the vehicle is under acceleration. The longitudinal accelerometer voltage signal increases when the vehicle is under deceleration. The usable output voltage range for the longitudinal accelerometer is 0.48-4.82 volts. The longitudinal accelerometer sensor bias compensates for sensor mounting alignment errors and electronic signal errors.

DTC Descriptor

This diagnostic procedure supports the following DTCs:

DTC C0191 Four Wheel Drive Reference Accelerometer Circuit

Conditions for Running the DTC
    • The ignition is ON.
    • The DTC can be set after system initialization.

Conditions for Setting the DTC

Voltage at the longitudinal accelerometer signal output to the EBCM falls outside the 0.48-4.82 volts range for more than 100 milliseconds.

Action Taken When the DTC Sets
    • A malfunction DTC is set.
    • The traction control system (TCS) is disabled.
    • The antilock brake system (ABS) warning indicator turns ON.

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

Diagnostic Aids
    • A thorough inspection of the wiring system and connectors be performed. Failure to carefully and fully inspect the wiring system and connectors may result in misdiagnosis which may result in replacing good parts and the reappearance of the malfunction.
    • Inspection for poor connections, broken insulation, or a wire that is broken inside the insulation.
    • If an intermittent malfunction exists refer to Testing for Intermittent Conditions and Poor Connections .

Test Description

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

  1. Tests for specified voltage on the LNG accelerometer signal circuit.

    2.

  2. Checks to see if voltage was below or above specified voltage.

    3.

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

    4.

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

    5.

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

    6.

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

    7.

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

    8.

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

    9.

  9. Tests for a short to ground, a high resistance, or an open in the lateral accelerometer signal circuit.

    10.

  10. Tests for a short to voltage in the lateral accelerometer signal circuit.

    11.

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

    12.

  12. Checks the LNG accelerometer sensor connector for poor connections.

Step

Action

Value(s)

Yes

No

Schematic Reference: Antilock Brake System Schematics

Connector End View Reference: Antilock Brake System Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

  1. Turn OFF the ignition.
  2. Disconnect the electronic brake control module (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 J 39200 , measure the voltage between pin 10 and pin 15 of the J 39700 .

Is the voltage within the specified value?

0.48 V-4.82 V

Go to Diagnostic Aids

Go to Step 3

3

  1. Disconnect the LNG accelerometer sensor.
  2. Using a J 39200 , measure the voltage between pin 10 and pin 15 of the J 39700 .

Is the voltage less than the specified value?

4.82 V

Go to Step 4

Go to Step 11

4

Using a DMM, measure the voltage between pin 10 and pin 18 of the J 39700 .

Is the voltage greater than the specified value?

0.48 V

Go to Step 5

Go to Step 10

5

Using a DMM, measure the voltage between the 5-volt reference circuit pin 28 and the ground circuit pin 15 on the J 39700 .

Does the voltage measure less than the specified value?

2 V

Go to Step 9

Go to Step 6

6

Using a DMM, measure the voltage between the 5-volt reference circuit pin 28 and ground circuit pin 15 on the J 39700 .

Does the voltage measure greater than the specified voltage?

3 V

Go to Step 8

Go to Step 7

7

  1. Turn OFF the ignition.
  2. Disconnect the negative battery cable.
  3. Measure the resistance from the ground circuit of the LNG accelerometer to a good ground.

Does the resistance measure less than the specified value?

5 ohms

Go to Step 14

Go to Step 12

8

Test the 5-volt reference circuit of the LNG accelerometer sensor for a short to voltage. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 17

Go to Step 13

9

Test the 5-volt reference circuit of the LNG accelerometer sensor for a short to ground, a high resistance, or an open. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 17

Go to Step 10

10

Test the LNG accelerometer signal circuit of the LNG accelerometer sensor for a short to ground, a high resistance, or an open. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 17

Go to Step 13

11

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

Did you find and correct the condition?

--

Go to Step 17

Go to Step 13

12

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

Did you find and correct the condition?

--

Go to Step 17

Go to Step 13

13

Inspect for poor connections at the harness connector of the LNG accelerometer sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

--

Go to Step 17

Go to Step 15

14

Inspect for poor connections at the harness connector of the EBCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

--

Go to Step 17

Go to Step 16

15

Replace the vehicle LNG accelerometer sensor. Refer to Longitudinal Accelerometer Replacement .

Did you complete the replacement?

--

Go to Step 17

--

16

Replace the EBCM. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

--

Go to Step 17

--

17
  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