Circuit Description

WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

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 k-5 k ohms with a maximum current draw of less than 16 ma. The BPP sensor will output an analog signal that is referenced to 5 volt 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 degrees rotation of the brake pedal pivot. Out-of-range values will be provided outside of the 32 degrees 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 three circuits:

5-volts 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.