Circuit Description

The supercharger inlet absolute pressure (SCIP) sensor measures the pressure after the throttle body, but before the supercharger. Pressure in this area is affected by engine speed, throttle opening, air temperature, and barometric pressure (BARO). A diaphragm within the SCIP sensor is displaced by the pressure changes that occur from the varying load and operating conditions of the engine. The sensor translates this action into electrical resistance. The SCIP sensor wiring includes 3 circuits. The engine control module (ECM) supplies a regulated 5 volts to the sensor on a 5-volt reference circuit. The ECM supplies a ground on a low reference circuit. The SCIP sensor provides a signal voltage to the ECM, relative to the pressure changes, on the SCIP sensor signal circuit. The ECM converts the signal voltage input to a pressure value.

Under normal operation the highest pressure that can exist in the supercharge intake manifold is equal to BARO. This occurs when the vehicle is operated at wide-open throttle (WOT) or when the ignition is ON while the engine is OFF. The lowest manifold pressures occur when the vehicle is idling or decelerating. SCIP can range from 20-30 kPa, when pressures are low, to as much as BARO when pressures are high. The ECM monitors the SCIP sensor signal for pressure outside of the normal range.