Circuit Description
The master cylinder pressure sensor is part of the electronic brake control module (EBCM).
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC C1281 Master Cylinder Pressure Sensor Signal
Conditions for Running the DTC
The vehicle speed is at least 7 km/h (4 mph).
Conditions for Setting the DTC
The EBCM detects an incorrect master cylinder pressure sensor voltage.
Action Taken When the DTC Sets
| • | The Antilock Brake System (ABS) warning indicator turns ON. |
| • | The ABS is disabled. |
| • | The vehicle stability control (VSC) warning indicator turns ON. |
| • | The VSC is disabled. |
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, high resistance, or short in the stop lamp circuit to the EBCM. |
| • | 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 stop lamp circuit of the EBCM for a high resistance, an open, or a short to ground.
-
Test the stop lamp circuit of the EBCM for a short to voltage.
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? | 8-14 V | Go to Step 3 | Go to Step 4 | ||||||
3 | Measure the voltage between the stop lamp circuit of the EBCM and a good ground with the brake pedal released. Is the voltage as specified? | Below 1 V | Go to Step 6 | Go to Step 5 | ||||||
Test the stop lamp circuit of the EBCM for the following:
Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 7 | ||||||||
Test the stop lamp circuit of the EBCM for a short to voltage. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | 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 | ||||||
