P012D
DTC P012C or P012D
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptors
DTC P012C
- Supercharger Inlet Pressure Sensor Circuit Low Voltage
DTC P012D
- Supercharger Inlet Pressure Sensor Circuit High Voltage
Diagnostic Fault Information
Typical Scan Tool Data
Circuit Description
The supercharger inlet pressure 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). The sensor provides a signal voltage that varies relative to pressure changes that occur from the various load and operating conditions of the engine. The engine control module (ECM) supplies a regulated 5 V reference circuit, and monitors the signal circuit.
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 supercharger inlet pressure can range from 20 kPa to as much as BARO.
Conditions for Running the DTC
* The ignition is ON
* The DTCs run continuously when the above condition is met.
Conditions for Setting the DTC
P012C
The ECM detects that the supercharger inlet pressure sensor voltage is less than 0.2 V for greater than 5 s.
P012D
The ECM detects that the supercharger inlet pressure sensor voltage is greater than 4.5 V for greater than 5 s.
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 (LS3) [1][2]Electrical DiagramsEngine Controls Schematics (LS7) [1][2]Electrical DiagramsEngine Controls Schematics (LS9) [1][2]Electrical Diagrams
Connector End View Reference
Component Connector End Views 5 Bow Lowered Switch (CM7)
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References Control Module References for scan tool information
Special Tools
J23738-A - Mityvac
Circuit/System Verification
1. Verify that DTC P0641 is not set.
• If a DTC is set, refer to Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle for further diagnosis.
2. Ignition ON, engine OFF, observe the scan tool SC Inlet Pressure Sensor voltage parameter. The reading should be between 0.2-4.5 V.
3. Ignition ON, observe the scan tool SC Inlet Pressure Sensor pressure parameter. Start the engine and let it idle. The SC Inlet Pressure Sensor pressure parameter should decrease.
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
Note: You must perform the Circuit/System Verification before proceeding with the Circuit/System Testing.
1. Ignition OFF, disconnect the harness connector at the supercharger inlet pressure sensor.
2. Ignition OFF, and all vehicle systems OFF. It may take up to 2 minutes for all vehicle systems to power down. Test for less than 5 ohms between the low reference circuit terminal 2 and ground.
• If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
3. Ignition ON, test for 4.8-5.2 V between the 5 V reference circuit terminal 1 and ground.
• If less than the specified range, test the 5 V reference circuit for a short to ground or 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 (2.9 psi).
• If the greater than the specified range, test the signal circuit terminal 3 for a short to voltage. If the circuit tests normal, replace the ECM.
5. Install a 3 A fused jumper wire between the 5 V reference circuit terminal 1 and the signal circuit terminal 3. Verify the scan tool parameter is greater than 95 kPa (13.8 psi).
• If less than the specified range, 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 or replace the supercharger inlet pressure sensor.
Component Testing
Note: You must perform the Circuit System Testing before proceeding with the Component Testing.
Erratic Signal Test
1. Ignition OFF, remove the supercharger inlet pressure sensor.
2. Install a 3 A fused jumper between the harness connector 5 V reference circuit terminal 1 and terminal 1 or A of the sensor.
3. Install a jumper wire between the low reference circuit terminal 2 or B of the sensor and ground.
4. Connect a DMM between terminal 3 or C of the sensor and ground.
5. Ignition ON, slowly apply vacuum to the sensor with theJ23738-A while monitoring the voltage on the DMM. The voltage should vary between 0-5.2 V without any spikes or dropouts.
• If the voltage is not within the specified range or is erratic, replace the supercharger inlet pressure sensor.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Supercharger Air Inlet Pressure Sensor Replacement (LS9)
* Control Module References Control Module References for ECM replacement, programming, and setup