Diagnostic Instructions

DTC Descriptors

DTC P012C: Supercharger Inlet Pressure (SCIP) Sensor Circuit Low Voltage

DTC P012D: Supercharger Inlet Pressure (SCIP) Sensor Circuit High Voltage

Diagnostic Fault Information

SC Inlet Pressure Sensor

Circuit	Short to Ground	High Resistance	Open	Short to Voltage	Signal Performance
5-Volt Reference	P0107, P012C, P0452, P0641	P0069	P012C	P0641, P2229	--
SC Inlet Pressure Sensor Signal	P012C	P0069	P012C	P012D	P012B
Low Reference	--	P0069, P012B	P012B, P012D	--	--

Typical Scan Tool Data

SC Inlet Pressure Sensor

Circuit	Short to Ground	Open	Short to Voltage
Operating Conditions: Ignition is ON. Normal SC Inlet Pressure Sensor Parameter: BARO-- Altitude Versus Barometric Pressure
5-Volt Reference	8-12 kPa	8-12 kPa	96-104 kPa
SCIP Sensor Signal	8-12 kPa	8-12 kPa	96-104 kPa
Low Reference	--	96-104 kPa	--

SC Inlet Pressure Sensor, Volts

Circuit	Short to Ground	Open	Short to Voltage
Normal Range: Engine running 1.20-1.95 volts
5-Volt Reference	0.04 V	0.0 V	4.50-4.98 V
SCIP Sensor Signal	0.0 V	0.0 V	4.98 V
Low Reference	--	4.55-4.98 V	--

Circuit Description

The supercharger inlet absolute pressure (SCIAP) 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 SCIAP 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 SCIAP 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 SCIAP sensor provides a signal voltage to the ECM, relative to the pressure changes, on the SCIAP 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. The SCIAP can range from 20-30 kPa, when pressures are low, to as much as BARO when pressures are high. The ECM monitors the SCIAP sensor signal for pressure outside of the normal range.

Conditions for Running the DTC

P012C

P012D

Conditions for Setting the DTC

P012C

The ECM detects that the SCIAP sensor voltage is less than 0.10 volt for more than 5 seconds.

P012D

The ECM detects that the SCIAP sensor voltage is more than 4.80 volts for more than 5 seconds.

Action Taken When the DTC Sets

DTCs P012C and P012D are Type B DTCs.

Conditions for Clearing the MIL/DTC

DTCs P012C and P012D are Type B DTCs.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Special Tools Required

J 35555 Metal Mityvac

Circuit/System Verification

1. If DTCs P0641 or P0651 are set, refer to DTC P0641 or P0651 .
2. Verify the integrity of the SCIAP sensor system by inspecting for the following conditions:

•	Any damage to the SCIAP sensor housing

•	A loose or improperly installed SCIAP sensor

•	A restriction in the vacuum source of the SCIAP sensor

3. Ignition ON, observe the scan tool SC Inlet Pressure Sensor parameter. The reading should be BARO. Refer to Altitude Versus Barometric Pressure .
4. Engine running at idle, observe the scan tool SC Inlet Pressure Sensor parameter. The reading should CLOSELY match the MAP sensor value.
5. Engine running, observe the DTC information with a scan tool. DTCs P012C or P012D should not set.
6. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Circuit/System Testing

Important: You must perform the Circuit/System Verification before proceeding with the Circuit/System Testing.

1. Ignition OFF, disconnect the harness connector at the SCIAP sensor.
2. Ignition OFF, allow sufficient time for the ECM to power down. Test for less than 2 ohms of resistance between the low reference circuit and ground.

⇒	If greater than the specified range, test the low reference circuit terminal A for an open/high resistance. If the circuit tests normal, replace the ECM.

3. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal C and ground.

⇒	If less than the specified range, test the 5-volt reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.

4. Verify the scan tool SC Inlet Pressure Sensor parameter is less than 20 kPa.

⇒	If the greater than the specified parameter, test the signal circuit terminal B for a short to voltage. If the circuit tests normal, replace the ECM.

5. Install a 3A fused jumper wire between the 5-volt reference circuit and the signal circuit. Verify the scan tool parameter is greater than 95 kPa.

⇒	If less than the specified parameter, test the signal circuit for a short to ground, open/high resistance. If the circuit tests normal, replace the ECM.

6. If all circuits test normal, test the SCIAP sensor. Refer to Component Testing for instructions.

Component Testing

Important: You must perform the Circuit System Testing before proceeding with the Component Testing.

1. Ignition OFF, remove the SCIAP sensor.
2. Install a 3A fused jumper wire between the 5-volt reference terminal C of the sensor and 5-volt reference.
3. Install a jumper wire between the low reference terminal A of the sensor and ground.
4. Install a jumper wire at the signal terminal B of the sensor.
5. Connect a DMM between the jumper wire from terminal B of the sensor and ground.
6. Ignition ON, install the J 35555 to the sensor vacuum port. Slowly apply vacuum to the sensor while monitoring the voltage on the DMM. The voltage should vary between 4.9-0.04 volts, without any spikes or dropouts.

⇒	If the voltage is not within the specified range or is erratic, replace the SCIAP sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.