C0284
DTC C0284
Circuit Description
The brake pedal position (BPP) sensor provides an analog pedal position signal. Its output is hardwired to the electro-hydraulic power steering (EHPS) connector. The signal must be digitized and differentiated within the EHPS module to provide the necessary pedal rate signal.
The BPP sensor is a resistive sensor with a total resistance between 3,000 - 5,000 ohms with a maximum current draw of less than 16 ma. The BPP sensor will output an analog signal that is referenced to 5 volts which may increase or decrease monotonically with brake pedal depression. The sensor analog output shall have a specified electrical output over a mechanical range of 32° rotation of the brake pedal pivot. Out-of-range values will be provided outside of the 32° range. The EHPS module monitors the brake pedal position information from the BPP sensor every 5 milliseconds (200 Hz) for proper operation.
The BPP sensor contains the following 3 circuits:
^ 5 volt reference circuit
^ Signal circuit
^ Low reference circuit
The EHPS excites the BPP sensor with the 5 volt reference and can determine the brake pedal position by reading the signal circuit output. The brake pedal travel is physically constrained to only use a portion of the BPP sensor. A portion of the BPP sensor is reserved for circuit low and circuit high guard bands. This diagnostic, DTC C0284, is used to determine if the sensor output reports a voltage in the high guard band.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC C0284 Brake Pedal Position Sensor Circuit High
Conditions for Running the DTC
^ The EHPS module is in RUN mode.
^ The ignition switch is in the ACC or ON position.
^ Battery voltage is between 12 - 58 volts.
Conditions for Setting the DTC
^ The output voltage ratio sensed by the EHPS module is greater than 98.44 percent of the excitation voltage.
^ The BPP sensor fork is off of the brake pedal pin.
Action Taken When the DTC Sets
^ System operation is reduced.
^ The SERVICE BRAKE SYSTEM message will be displayed.
^ Ramp the motor speed input to the commanded flow resolved from a default brake pedal position.
^ Stores a DTC C0284 in the powertrain control module (PCM).
^ History DTC C0284 will be set in the PCM.
Conditions for Clearing the DTC
^ The output voltage ratio sensed by the EHPS module drops below 98.44 percent of the excitation voltage.
^ Using the scan tool
^ A history DTC will clear after 255 consecutive ignition cycles if the condition for the malfunction is no longer present.
Diagnostic Aids
It may be necessary to check Testing for Intermittent Conditions and Poor Connections.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
2. This step checks the Input Voltage data parameter.
3. This step checks the Output Voltage data parameter.
4. This step tests for an open or short to voltage in the BPP sensor 5 volt supply circuit.
5. This step tests for an open or short to voltage in the BPP sensor 5 volt return circuit.
6. This step tests for a short to voltage in the BPP sensor signal circuit.
