Circuit Description
The longitudinal sensor is part of the yaw/lateral sensor assembly. The longitudinal sensor only used on 4-wheel drive (4WD) vehicles. 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 deceleration. The longitudinal accelerometer voltage signal increases when the vehicle is under acceleration. 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 DTC:
DTC C0287 Longitudinal Accelerometer Circuit
Conditions for Running the DTC
| • | The ignition is ON. |
| • | The vehicle stability enhancement system (VSES) sensors have been successfully initialized or the message center has displayed the stability system disabled message due to an unsuccessful initialization attempt. Refer to ABS Description and Operation for a complete explanation of VSES sensor initialization. |
| • | The vehicle is being driven relatively straight and level at a speed greater than 11 km/h (7 mph), before performing a stable turning maneuver. |
Conditions for Setting the DTC
Any of the following conditions may cause the DTC to set:
| • | Open longitudinal accelerometer circuitry is detected. |
| • | Shorted longitudinal accelerometer circuitry is detected. |
| • | An erratic longitudinal accelerometer signal is detected. |
| • | The EBCM detects that the longitudinal accelerometer sensor signal does not correspond with signals from other sensors. |
Action Taken When the DTC Sets
| • | The EBCM disables the VSES. |
| • | The stability indicator turns ON. |
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
| • | Communicate with the customer to determine the conditions under which the message center displays the Service Stability System message. Learning the conditions under which the DTC sets may help you duplicate the failure. |
| • | Use the Snapshot function on the scan tool in order to assist you in locating an intermittent malfunction. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step tests the sensor 5-volt reference circuitry and ground circuit.
-
This step tests the sensor signal circuit for an open or high resistance.
Step | Action | Values | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
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Important:
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 - Vehicle? | -- | Go to Step 2 | |||||||||
2 |
Does the DTC reset? | -- | Go to Step 3 | Go to Diagnostic Aids | ||||||||
Does the voltage measure greater than the specified value? | 4.75 V | Go to Step 5 | Go to Step 4 | |||||||||
Test the longitudinal accelerometer signal circuit for the following conditions:
Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 6 | |||||||||
5 |
Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 7 | ||||||||
6 | Inspect for poor connections at the harness connector of the electronic brake control module (EBCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 8 | ||||||||
7 |
Important: Replace the accelerometer/yaw rate sensor. Following EBCM reprogramming, perform the set-up procedure for the EBCM. Use the scan tool to perform the Tire Size Calibration procedure. Replace the yaw rate sensor/longitudinal accelerometer. Refer to Control Module References . Did you complete the replacement? | -- | Go to Step 9 | -- | ||||||||
8 |
Important: Following EBCM replacement, perform the set-up procedure for the EBCM. Use the scan tool to perform the Tire Size Calibration procedure. Replace the EBCM. Refer to Control Module References . Did you complete the replacement? | -- | Go to Step 9 | -- | ||||||||
9 |
Does the DTC reset? | -- | Go to Step 3 | System OK | ||||||||
