Circuit Description
The manifold absolute pressure (MAP) sensor that resides in the engine intake manifold is integrated with the intake air temperature (IAT) sensor 2. The purpose of this integrated sensor is to measure the following:
| • | The atmospheric pressure and the vacuum or the reduced pressure that exists under different operating conditions in the engine intake manifold |
| • | The supercharged air pressure that exists under high load or wide open throttle conditions in the engine intake manifold |
| • | The IAT 2 after the supercharger and the intercooler as it enters the engine intake manifold |
| • | The IAT 2 after the supercharger bypass valve and the intercooler as it enters the engine intake manifold |
The MAP/IAT sensor 2 has the following types of circuits:
| • | A powertrain control module (PCM) supplied and regulated MAP 5-volt reference circuit |
| • | A PCM supplied ground for the low reference circuit that is shared by the MAP and the IAT sensor 2 |
| • | A MAP sensor signal circuit that supplies a voltage input to the PCM |
| • | A PCM supplied 5-volt, IAT signal circuit |
The diaphragm within the MAP sensor responds to all of the various pressure changes in the intake manifold, and provides a signal voltage to the PCM on the signal circuit, relative to those pressure changes.
The PCM monitors the MAP sensor signal for voltage that is outside of the normal range of a properly operating sensor. If the PCM detects a MAP sensor signal voltage that is excessively high, DTC P0108 sets.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0108 Manifold Absolute Pressure (MAP) Sensor Circuit High Voltage
Conditions for Running the DTC
| • | DTCs P0120, P0121, P0220, P2135 are not set. |
| • | The engine has been running for a calibrated length of time, that is determined by the start-up engine coolant temperature (ECT). The length of time ranges from 2 minutes at less than -30°C (-22°F) to 1 second at more than 30°C (86°F). |
| • | The TP Indicated Angle parameter is less than 90 percent, when the engine speed is less than 1,000 RPM. |
| OR |
| • | The TP Indicated Angle parameter is less than 98 percent, when the engine speed is more than 1,000 RPM. |
| • | DTC P0108 runs continuously when the above conditions are met. |
Conditions for Setting the DTC
The PCM detects that the MAP sensor signal voltage is more than 4.90 volts for more than 2 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. |
Test Description
The number below refers to the step number on the diagnostic table.
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 | ||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |
Is DTC P0651 set? | -- | Go to DTC P0651 | Go to Step 3 | |
3 | Observe the MAP Sensor parameter with a scan tool. Is the MAP Sensor parameter more than the specified value? | 4.90 V | Go to Step 5 | Go to Step 4 |
4 |
Did the DTC fail this ignition? | -- | Go to Step 5 | Go to Testing for Intermittent Conditions and Poor Connections |
5 |
Is the MAP Sensor parameter less than the specified value? | 0.20 V | Go to Step 6 | Go to Step 7 |
6 |
Is the voltage more than the specified value? | 0.20 V | Go to Step 8 | Go to Step 9 |
7 | Test the MAP sensor signal circuit between the powertrain control module (PCM) and the MAP sensor for a short to voltage. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 10 |
8 | Test the MAP sensor low reference circuit between the PCM and the MAP sensor for a high resistance or for an open. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 10 |
9 | Test for an intermittent and for shorted terminals and for a poor connection at the MAP sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 11 |
10 | Test for an intermittent and for shorted terminals and for a poor connection 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 13 | Go to Step 12 |
11 | Replace the MAP sensor. Refer to Manifold Absolute Pressure Sensor Replacement . Did you complete the replacement? | -- | Go to Step 13 | -- |
12 | Replace the PCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 13 | -- |
13 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 14 |
14 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |
