Circuit Description
The electronic brake control module (EBCM) monitors the deceleration of the vehicle for Antilock Brake System (ABS) operation.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC C1279 Deceleration Sensor
Conditions for Running the DTC
DTC C1279 can be set anytime the ignition switch is in the ON position.
Conditions for Setting the DTC
The EBCM detects a malfunction in the deceleration sensor.
Action Taken When the DTC Sets
The ABS warning indicator turns ON.
Conditions for Clearing the DTC
The condition responsible for setting the DTC no longer exists and the scan tool Clear DTCs function is used.
Diagnostic Aids
Thoroughly inspect the wiring and the connectors. An incomplete inspection of the wiring and the connectors may result in a misdiagnosis, causing a part replacement with the reappearance of the malfunction.
The following are possible causes of the malfunction:
| • | An open or short in deceleration signal circuit |
| • | An open or high resistance in the deceleration voltage circuit |
| • | An open or high resistance in the deceleration sensor ground circuit |
| • | A deceleration sensor malfunction |
| • | An internal EBCM malfunction |
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.
-
Test the sensor voltage circuit for a high resistance, an open, or a short.
-
Test the sensor ground circuit for a high resistance or open.
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 | |||||||
2 |
Is the voltage within the specified range? | 10-14 V | Go to Step 5 | Go to Step 3 | ||||||
Test the sensor voltage circuit for the following:
Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 7 | Go to Step 4 | |||||||
Test the sensor ground circuit for a high resistance or open. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 7 | Go to Step 5 | |||||||
5 | Replace the yaw rate sensor . Refer to Vehicle Yaw Sensor Replacement . Did you complete the replacement? | -- | Go to Step 7 | -- | ||||||
6 | Replace the brake pressure modulator valve (BPMV). Refer to Brake Pressure Modulator Valve Assembly Replacement . Did you complete the replacement? | -- | Go to Step 7 | -- | ||||||
7 |
Does the DTC reset? | -- | Go to Step 2 | System OK | ||||||
