DTC Descriptors
DTC P012C: Supercharger Inlet Absolute Pressure (SCIAP) Sensor Circuit Low VoltageDTC P012D: Supercharger Inlet Absolute Pressure (SCIAP) Sensor Circuit High Voltage
Diagnostic Fault Information
Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
Circuit | Short to Ground | High Resistance | Open | Short to Voltage | Signal Performance |
|---|---|---|---|---|---|
5-Volt Reference | P0452, P0532, P0641 | P012C | P012C | P0533, P0641 | -- |
SCIAP Sensor Signal | P012C | P012C | P012C | -- | P1101 |
Low Reference | -- | P012B, P012D | P012B, P012D | -- | -- |
Typical Scan Tool Data
Circuit | Short to Ground | Open | Short to Voltage |
|---|---|---|---|
Operating Conditions: The ignition is ON, with the engine running. Normal SCIAP Parameter: 12-103 kPa | |||
5-Volt Reference | 8-12 kPa | 8-12 kPa | 207 kPa |
SCIAP Sensor Signal | 8-12 kPa | 8-12 kPa | 207 kPa |
Low Reference | -- | 191 kPa | -- |
Circuit | Short to Ground | Open | Short to Voltage |
|---|---|---|---|
5-Volt Reference | 0.0 V | 0.0 V | 4.98 V |
SCIAP Sensor Signal | 0.0 V | 0.0 V | 4.98 V |
Low Reference | -- | 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 the intake manifold 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 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. Under these conditions, the ECM uses the SCIAP sensor to determine the current BARO. The lowest manifold pressures occur when the vehicle is idling or decelerating. SCIAP can range from 8-10 kPa, when pressures are low, to as much as 207 kPa when pressures are high, depending on the BARO. 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 more than 0 percent when the engine speed is less than 800 RPM. |
| OR |
| The throttle angle is more than 12 percent when the engine speed is more than 800 RPM. |
| • | This DTC runs continuously within the enabling conditions. |
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 more 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 more than 1,200 RPM. |
| • | This DTC runs continuously within the enabling conditions. |
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
| • | The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. |
| • | The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
| • | A current DTC, Last Test Failed, clears when the diagnostic runs and passes. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
| • | Clear the MIL and the DTC with a scan tool. |
Reference Information
Schematic Reference
Connector End View Reference
Electrical Information Reference
Scan Tool Reference
Circuit/System Verification
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 |
Circuit/System Testing
- With the ignition OFF, disconnect the harness connector at the SCIAP sensor.
- With the ignition ON and the engine OFF, connect a test lamp between the SCIAP sensor 5-volt reference circuit and a good ground. With a DMM, measure for a voltage range of 4.8-5.2 volts, from the SCIAP sensor 5-volt reference circuit to a ground.
- With the SCIAP sensor harness connector still disconnected, observe the SCIAP Sensor parameter for a value of less than 12 kPa with a scan tool.
- Connect a 3-amp fused jumper wire between the SCIAP sensor 5-volt reference circuit and the signal circuit of the SCIAP sensor and verify the SCIAP sensor parameter is more than 103 kPa.
- Turn OFF the ignition, and all electrical accessories. Allow sufficient time for the control module to power down before taking a resistance measurement. Measure for a value of less than 5 ohms of resistance between the low reference circuit of the SCIAP sensor and a ground.
Important:
• The test lamp is used to load the circuit and may not illuminate. • The SCIAP sensor 5-volt reference circuit is spliced to other components of the vehicle.
| ⇒ | If the voltage is less than the specified range, test the circuit for an open, high resistance, or a short to ground. If the SCIAP sensor 5-volt reference circuit and connections tests normal, replace the ECM. |
| ⇒ | If the voltage is more than the specified range, test the circuit for a short to voltage. If the SCIAP sensor 5-volt reference circuit tests normal, replace the ECM. |
| ⇒ | If the SCIAP Sensor parameter is more than 12 kPa, test the SCIAP sensor signal circuit for a short to voltage. If the SCIAP sensor signal circuit tests normal, replace the ECM. |
| ⇒ | If the SCIAP Sensor parameter is less than 103 kPa, test the SCIAP sensor signal circuit for an open, high resistance, or a short to ground. If the SCIAP sensor signal circuit tests normal, replace the ECM. |
| ⇒ | If the resistance is more than 5 ohms, test the circuit for an open or high resistance. If the SCIAP sensor low reference circuit tests normal, replace the ECM. |
| ⇒ | If the SCIAP sensor circuits test normal, 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 |
