P012D
DTC P012C or P012D
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.
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
Typical Scan Tool Data
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
* DTCs P0120, P0121, P0122, P0123, P0220, P0221, P0222, P0223, P0641, or P0651 are not set.
* The throttle angle is greater than 0 percent when the engine speed is less than 800 RPM.
OR
The throttle angle is greater than 12 percent when the engine speed is greater than 800 RPM.
* This DTC runs continuously when the above enabling conditions are met.
P012D
* DTCs P0120, P0121, P0122, P0123, P0220, P0221, P0222, P0223, P0641, or P0651 are not set.
* The engine has been running for a period of time that is determined by the start-up engine coolant temperature (ECT). The time ranges from 4 minutes at less than -30°C (-22°F) to 2 seconds at greater than 30°C (86°F).
* The throttle angle is less than one percent when the engine speed is less than 1,200 RPM.
OR
The throttle angle is less than 20 percent when the engine speed is greater than 1,200 RPM.
* This DTC runs continuously when the above enabling conditions are met.
Conditions for Setting the DTC
P012C
The ECM detects that the SCIAP sensor voltage is less than 0.10 volt for greater than 5 seconds.
P012D
The ECM detects that the SCIAP sensor voltage is more than 4.80 volts for greater 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 (Electrical Diagrams)
Connector End View Reference
Component Connector End Views (Connector Views)
Electrical Information Reference
* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Diagnostic Trouble Code Descriptions)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
Special Tools
J 23738-A Mityvac
J 35555 Metal Mityvac
Circuit/System Verification
1. Verify that DTCs P0641 or P0651 are not set.
• If any of the DTCs are set, refer to DTC P0641 or P0651 (P0641) .
2. Ignition ON, observe the scan tool SC Inlet Pressure Sensor parameter. The reading should be BARO. Refer to Altitude Versus Barometric Pressure (Altitude Versus Barometric Pressure) .
3. Engine running at idle, observe the scan tool SC Inlet Pressure Sensor parameter. The reading should CLOSELY match the MAP Sensor parameter value.
4. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. 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. 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
2. Ignition OFF, disconnect the harness connector at the SCIAP sensor.
3. Ignition OFF for 90 seconds, test for less than 5 ohms 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.
4. 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 a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
5. 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.
6. Install a 3A fused jumper wire between the 5-volt reference circuit terminal C and the signal circuit terminal B. 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.
7. If all circuits test normal, test or replace the SCIAP sensor.
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, with the J 23738-A or J 35555 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 (Verification Tests) after completing the diagnostic procedure.
* Supercharger Air Inlet Pressure Sensor Replacement (Supercharger Air Inlet Pressure Sensor Replacement)
* Control Module References (Programming and Relearning) for ECM replacement, setup, and programming