Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptor
DTC P012B: Supercharger Inlet Pressure Sensor PerformanceDiagnostic Fault Information
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
Circuit | Short to Ground | Open | Short to Voltage |
|---|---|---|---|
Normal range is BARO with ignition ON. Refer to Altitude Versus Barometric Pressure . | |||
5-Volt Reference | 8-12 kPa | 8-12 kPa | 96-104 kPa |
SC Inlet Pressure Sensor Signal | 8-12 kPa | 8-12 kPa | 96-104 kPa |
Low Reference | -- | 96-104 kPa | -- |
Circuit Description
Important: The following applies to the intake airflow system performance diagnostic that is used in this supercharged engine:
• When referring to the supercharger intake manifold models, the plenum volume between the throttle body and the supercharger is considered to be the intake manifold. • When referring to engine pumping, the supercharger and the intercooler plenum are considered to be part of the engine. • The manifold absolute pressure (MAP) estimates are used in the engine air flow estimates. Air flow into the intake system must be the same as the air flow out of the intake system, the Intake Airflow Rationality Diagnostics (IFRD) calculates air
flowing out of the engine based on MAP estimates, volumetric efficiency, and RPM.
The intake airflow system performance diagnostic provides the within-range rationality check for the mass air flow (MAF), supercharger inlet absolute pressure (SCIAP), MAP, by-pass valve stuck, and the throttle position (TP) sensors. This is an explicit model-based diagnostic containing 4 separate models for the intake system.
| • | The throttle model describes the flow through the throttle body and is used to estimate the MAF through the throttle body as a function of barometric pressure (BARO), throttle position, intake air temperature (IAT), and estimated SCIAP. The information from this model is displayed on the scan tool as the MAF Performance Test parameter. |
| • | The first supercharger intake manifold model describes the pressure at the supercharger intake manifold and is used to estimate SCIAP as a function of the MAF into the intake manifold from the throttle body and the MAF out of the intake manifold caused by engine pumping. The flow into the supercharger intake manifold from the throttle uses the MAF estimate calculated from the above throttle model. The information from this model is displayed on the scan tool as the MAP Performance Test 1 parameter. |
| • | The second supercharger intake manifold model is identical to the first supercharger intake manifold model except that the MAF sensor measurement is used instead of the throttle model estimate for the throttle air input. The information from this model is displayed on the scan tool as the MAP Performance Test 2 parameter. |
| • | A fourth model is created from the combination and additional calculations of the throttle model and the first supercharger intake manifold model. The information from this model is displayed on the scan tool as the TP Performance Test parameter. |
| • | In addition 5 new models have been added, these models run in the background. |
The estimates of MAF, SCIAP, and TP that are obtained from this system of models and calculations are then compared to the actual measured values from the MAF, SCIAP, and the TP sensors and to each other to determine the appropriate DTC to fail. The following table illustrates the possible failure combinations and the resulting DTC or DTCs.
MAF Performance Test | MAP Performance Test 1 | MAP Performance Test 2 | TP Performance Test | DTCs Passed | DTCs Failed |
X | X | OK | OK | P0101, P0121, P012B, P1101 | None |
OK | OK | Fault | OK | P0101, P0121, P012B, P1101 | None |
Fault | OK | Fault | OK | P0121, P012B, P1101 | P0101 |
OK | Fault | Fault | OK | P0101, P0121, P1101 | P012B |
Fault | Fault | Fault | OK | P0121, P1101 | P0101 P012B |
X | X | OK | Fault | P0101, P012B, P1101 | P0121 |
OK | OK | Fault | Fault | P0101, P0121, P012B, P1101 | None |
Fault | OK | Fault | Fault | P0101, P0121, P012B | P0101, P1101 |
X | Fault | Fault | Fault | P0101, P0121, P012B | P0101, P1101 |
Conditions for Running the DTC
| • | DTCs P0096, P0097, P0098, P0102, P0103, P0111, P0112, P0113, P0117, P0118, P0120, P0121, P0128, P012C, P012D, P0220, P0401, P0405, P0506, P0507, P1404, P2135 are not set. |
| • | The engine speed is between 500-5,000 RPM. |
| • | The engine coolant temperature (ECT) is between 70-129°C (158-264°F). |
| • | The IAT is between -7 to +125°C (+19 to +257°F). |
| • | The change in the TP is less than 5 percent. |
| • | The above enabling criteria must be stable for more than 5 seconds. |
| • | DTC P012B runs continuously when the above conditions are met. |
Conditions for Setting the DTC
The engine control module (ECM) detects that the actual measured intake system parameters from the MAF, MAP, SC Inlet Pressure and TP sensors are not within a range of the corresponding calculated parameters that are derived from the system of models by greater than a calibrated threshold for greater than 10 seconds.
Action Taken When the DTC Sets
DTC P012B is a Type B DTC.
Conditions for Clearing the MIL/DTC
DTC P012B is a Type B DTC.
Reference Information
Schematic Reference
Connector End View Reference
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Special Tools Required
J 35555 Metal Mityvac
Diagnostic Aids
This DTC may set due to any of the following conditions:
| • | Any condition that can cause the MAF, MAP, SCIAP, and TP sensors to be shifted in value |
| • | A resistance of 10-20 ohms on the 5-volt reference or low reference circuits of the SCIAP sensor |
| • | Any condition that may cause the supercharger by-pass valve to bind or stick in either the open or closed positions |
Caution: Refer to Road Test Caution in the Preface section.
| • | Road test the vehicle and verify that the MAF sensor calculated g/s and the actual MAF g/s parameters are near or equal to each other. |
| • | A steady or intermittent high resistance of 15 ohms or more on the ignition 1 voltage circuit will cause the MAF sensor values to be skewed high by up to 60 g/s. |
| • | A skewed or stuck ECT, MAF/IAT, or IAT sensor 2 will cause the calculated models to be inaccurate and may cause this DTC to run when it should not. Refer to Temperature Versus Resistance . |
Circuit/System Verification
- If DTCs P0102, P0103, P0106, P0107, P0108, P0121, P0641, P0651, P2228, or P2229 are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle for further information.
- Ignition OFF, verify the integrity of the entire supercharger air induction system, inspecting for the air induction system for the following conditions:
- Inspect the vacuum lines for cracking, loose fit, or for improper routing at the following locations:
- Inspect the by-pass valve and cable for any of the following conditions:
- Ignition ON, observe the MAP and SC Inlet Pressure Sensor kPa parameters with a scan tool. Start the engine and let it idle. The MAP and SC Inlet Pressure Sensor kPa parameters should decrease and closely match each other.
- Ignition ON, depress the accelerator pedal completely and observe the TP Indicated Angle parameter with a scan tool. The TP Indicated Angle parameter should read 98-100 percent.
- Ignition ON, perform a snapshot of the throttle actuator control (TAC) data while performing the following action. Refer to Scan Tool Snapshot Procedure .
- Engine running, on a road test perform a brief wide open throttle (WOT) acceleration from 30 mph. The MAP sensor parameter on the scan tool should increase rapidly. This increase should be from approximately 35 kPa at idle to greater than 135 kPa.
- Engine running, observe the DTC information with a scan tool. DTC P012B should not set.
- 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.
| • | A restricted or collapsed air intake duct |
| • | A misaligned or damaged air intake duct |
| • | A dirty or deteriorating air filter element |
| • | Any objects blocking the air inlet probe of the MAF/IAT sensor |
| • | Any contamination or debris on the sensing elements in the probe of the MAF/IAT sensor |
| • | Any water intrusion in the induction system |
| • | Any vacuum leak downstream of the MAF/IAT sensor |
| • | An intake manifold leak |
| • | A BARO sensor that is skewed or stuck |
| • | The SCIAP sensor |
| • | The MAP sensor |
| • | The by-pass valve solenoid |
| • | The by-pass valve actuator |
| • | Sticking in either the open or closed position |
| • | Binding when opening or closing |
| • | Incorrectly adjusted cable |
| • | Any damage |
| ⇒ | If any of the above conditions are found, refer to Supercharger Cleaning and Inspection . |
| ⇒ | If the MAP Sensor kPa parameter does not decrease, refer to DTC P0106 . |
| ⇒ | If the TP Indicated Angle parameter is not within the specified range, refer to DTC P1516, P2101, P2119, or P2176 . |
| 7.1. | Slowly depress the accelerator pedal to WOT position and then slowly release the pedal. Exit from the snapshot and review the data. |
| 7.2. | Compare the TP Sensor 1 and the TP Sensor 2 parameters, frame by frame. The difference between the parameters should be less than 4 percent. |
| ⇒ | If the TP Sensor 1 and Sensor 2 parameter difference is greater than 4 percent, refer to DTC P0120, P0122, P0123, P0220, P0222, P0223, or P2135 . |
Caution: Refer to Road Test Caution in the Preface section.
| ⇒ | If less than the specified range, refer to Boost Control System Diagnosis . |
Circuit/System Testing
Important:
• The harness connectors for the following sensors are of the same configuration but are not interchangeable. Review the engine controls schematics for the BARO sensor and for the SCIAP sensor and note the circuit colors. Inspect the wiring harness
of the BARO sensor for the proper connections. Inspect the wiring harness of the SCIAP sensor for the proper connections. • You must perform Circuit/System Verification before proceeding with the Circuit/System Testing.
- Ignition OFF, disconnect the harness connector at the SCIAP sensor.
- Ignition OFF, allow sufficient time for the control module to power down. Test for less than 5 ohms of resistance between the low reference circuit terminal A and ground.
- Verify the scan tool SC Inlet Pressure parameter is less than 20 kPa.
- 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 all circuits test normal, test the SCIAP sensor. Refer to Component Testing for instructions.
| ⇒ | If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM. |
| ⇒ | If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the ECM. |
| ⇒ | 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. |
Component Testing
Important: You must perform the Circuit/System Testing before proceeding with the Component Testing.
- Ignition OFF, remove the SCIAP sensor.
- Install a 3A fused jumper wire between the 5-volt reference terminal C of the sensor and a 5-volt reference.
- Install a jumper wire between the low reference terminal A of the sensor and ground.
- Install a jumper wire at the signal terminal B of the SCIAP sensor.
- Connect a DMM between the jumper wire from terminal B of the SCIAP sensor and ground.
- Ignition ON, install the J 35555 to the SCIAP sensor vacuum port. Slowly apply vacuum to the sensor while monitoring the voltage on the DMM. The voltage should vary between 4.9-0.4 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.
| • | Control Module References for ECM replacement, setup, and programming |
