GM Service Manual Online
For 1990-2009 cars only

Circuit Description

Important: The following applies to the intake air flow system performance diagnostic that is used in this supercharged engine:

   • When referring to the "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) sensor that resides in the engine intake manifold is used to adjust the engine air flow estimates to balance the air flow models.

The intake air flow system performance diagnostic provides the within-range rationality test for the mass air flow (MAF), the supercharger inlet pressure (SCIP), and the throttle position (TP) sensors. This is an explicit model-based diagnostic containing four 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 SCIP.
    • The first intake manifold model describes the intake manifold and is used to estimate SCIP 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 intake manifold from the throttle uses the MAF estimate calculated from the throttle model.
    • The second intake manifold model is identical to the first intake manifold model except that the MAF sensor measurement is used instead of the throttle model estimate for the throttle air input.
    • A fourth model is created from the combination and additional calculations of the throttle model and the first intake manifold model.

The estimates of the MAF, the SCIP, and the TP that are obtained from this system of models and calculations are then compared to the actual measured values from the MAF, the SCIP, 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.

Throttle Model

First Intake Manifold Model

Second Intake Manifold Model

Fourth Model

DTCs Passed

DTCs Failed

X

X

Pass

Pass

P0101

P0121

P1101

P1182

None

Pass

Pass

Failed

Pass

P0101

P0121

P1101

P1182

None

Failed

Pass

Failed

Pass

P0121

P1101

P1182

P0101

Pass

Failed

Failed

Pass

P0101

P0121

P1101

P01182

Failed

Failed

Failed

Pass

P0121

P1101

P0101

P1182

X

X

Pass

Failed

P0101

P1101

P1182

P0121

Pass

Pass

Failed

Failed

P0101

P0121

P1101

P1182

None

Failed

Pass

Failed

Failed

P0101

P0121

P1182

P1101

X

Failed

Failed

Failed

P0101

P0121

P1182

P1101

If the powertrain control module (PCM) detects that the actual measured air pressure from the SCIP sensor is not within range of the calculated air pressure for the SCIP sensor that is derived from the system of models, DTC P1182 sets.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P1182 Supercharger Inlet Pressure (SCIP) Sensor Performance

Conditions for Running the DTC

    • DTCs P0120, P0121, P0220, P0506, P0507, P1183, P1184, P2135 are not set.
    • The engine speed is between 400-6,400 RPM.
    • The engine coolant temperature (ECT) is between 70-125°C (158-257°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 P1182 runs continuously when the above conditions are met.

Conditions for Setting the DTC

The PCM detects that the actual measured air pressure from the SCIP sensor is not within range of the calculated air pressure for the SCIP sensor that is derived from the system of models by more than 20 kPa for more than 0.5 second.

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.

Step

Action

Values

Yes

No

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Powertrain Control Module Connector End Views or Engine Controls Connector End Views or Boost Control System Diagnosis or Boost Control System Description

1

Did you perform the Diagnostic System Check - Vehicle?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

Observe the DTC information with a scan tool

Are DTCs P0641, P2228, P2229 set?

--

Go to DTC P0641 , DTC P2228 , and DTC P2229

Go to Step 3

3

Important: The harness connectors for the following sensors are of the same configuration but are not interchangeable.

  1. Turn OFF the ignition.
  2. Review the engine controls schematics for the barometric pressure (BARO) sensor and for the supercharger inlet pressure (SCIP) sensor and note the circuit colors.
  3. Inspect the wiring harness of the BARO sensor for the proper connection.
  4. Inspect the wiring harness of the SCIP sensor for the proper connection.

Did you find and correct the condition?

--

Go to Step 18

Go to Step 4

4

Inspect for the following conditions:

    • Disconnected, damaged, or incorrectly routed vacuum hoses
    • A supercharger or engine vacuum leak
    • A vacuum leak that is internal to the supercharger bypass valve actuator
    • A misaligned, loose, or damaged air intake duct
    • Any objects blocking the air inlet probe of the mass air flow (MAF)/Intake air temperature (IAT) sensor
    • Any contamination or debris on the sensing elements in the probe of the MAF/IAT sensor
    • A skewed BARO sensor--Refer to Altitude Versus Barometric Pressure .
    • Any damage or fractures to the SCIP sensor housing
    • Any damage to the BARO sensor housing
    • A missing or damaged SCIP sensor seal
    • Restrictions or debris in the SCIP sensor vacuum port

Did you find and correct the condition?

--

Go to Step 18

Go to Step 5

5

Inspect the throttle body and the throttle valve for the following conditions:

    • Any damage
    • Any restriction that could affect the air flow through it
    • A vacuum leak at the throttle body
    • Any missing parts
    • A throttle valve that is not fully open when the accelerator pedal is fully depressed

Did you find and correct the condition?

--

Go to Step 18

Go to Step 6

6

Test for an intermittent and for a poor connection at the SCIP sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

--

Go to Step 18

Go to Step 7

7

  1. Disconnect the SCIP sensor electrical connector.
  2. Observe the SC Inlet Pressure Sensor parameter with a scan tool.

Is the SC Inlet Pressure Sensor parameter less than the specified value?

0.1 V

Go to Step 8

Go to Step 11

8

  1. Turn ON the ignition, with the engine OFF.
  2. Connect a test lamp between the 5-volt reference circuit of the SCIP sensor at the harness connector and a good ground.
  3. Measure the voltage from the 5-volt reference circuit of the SCIP sensor to a good ground with a DMM.

Is the voltage within the specified range?

4.8-5.2 V

Go to Step 10

Go to Step 9

9

Is the voltage more than the specified value?

5.2 V

Go to Step 12

Go to Step 13

10

Important: All electrical components and accessories must be turned OFF.

  1. Turn OFF the ignition for 90 seconds to allow the control modules to power down.
  2. Measure the resistance from the low reference circuit of the SCIP sensor to a good ground with a DMM.

Is the resistance more than the specified value?

5 Ω

Go to Step 14

Go to Step 16

11

Test the SCIP sensor signal circuit between the powertrain control module (PCM) and the SCIP sensor for a short to voltage. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 18

Go to Step 15

12

Test all branches of the 5-volt reference circuit that is shared with the SCIP sensor for a short to voltage. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 18

Go to Step 15

13

Test the 5-volt reference circuit between the PCM and the SCIP sensor for a high resistance. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 18

Go to Step 15

14

Test the low reference circuit between the PCM and the SCIP sensor for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 18

Go to Step 15

15

Test for shorted terminals and for poor connections at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

--

Go to Step 18

Go to Step 17

16

Replace the SCIP sensor. Refer to Manifold Absolute Pressure Sensor Replacement .

Did you complete the replacement?

--

Go to Step 18

--

17

Replace the PCM. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

--

Go to Step 18

--

18

  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 90 seconds.
  3. Start the engine.
  4. 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.

Did the DTC fail this ignition?

--

Go to Step 2

Go to Step 19

19

Observe the Capture Info with a scan tool.

Are there any DTCs that have not been diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List - Vehicle

System OK