C0191

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. Component Tests and General Diagnostics

Test Description

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

2. Tests for specified voltage on the LNG accelerometer signal circuit.
3. Checks to see if voltage was below or above specified voltage.
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 voltage was above specified voltage.
7. Checks to see if resistance of ground circuit is less than 5 ohms.
8. Tests for a short to voltage on the 5-volt reference circuit.
9. Tests for a short to ground, a high resistance, or an open in the 5-volt reference circuit.
10. Tests for a short to ground, a high resistance, or an open in the lateral accelerometer signal circuit.
11. Tests for a short to voltage in the lateral accelerometer signal circuit.
12. Tests for a high resistance or an open in the ground circuit.
13. Checks the LNG accelerometer sensor connector for poor connections.

Step 1 - Step 9:

Step 10 - Step 17: