Circuit Description
The manifold absolute pressure (MAP) sensor measures the pressure inside the intake manifold. Pressure in the intake manifold is affected by engine speed, throttle opening, air temperature, and barometric pressure (BARO). A diaphragm within the MAP 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 MAP sensor wiring includes 3 circuits. The powertrain control module (PCM) supplies a regulated 5 volts to the sensor on a 5-volt reference circuit. The PCM supplies a ground on a low reference circuit. The MAP sensor provides a signal voltage to the PCM, relative to the pressure changes, on the MAP sensor signal circuit.
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 PCM uses the MAP sensor to determine the current BARO. The lowest manifold pressures occur when the vehicle is idling or decelerating. MAP can range from 10 kPa, when pressures are low, to as much as 105 kPa when pressures are high, depending on the BARO. The PCM monitors the MAP sensor signal for voltage outside of the normal range. If the PCM detects a MAP sensor signal voltage that is excessively high, DTC P0108 sets.
Conditions for Running the DTC
| • | DTCs P0121, P0122, P0123, P0641, P0651 are not set. |
| • | The engine has been running for a period of time that is determined by the start-up coolant temperature. The time ranges from 8 seconds at less than -30°C (-22°F) to 3 seconds at more than 30°C (86°F). |
| • | The throttle angle is less than 90 percent when the engine speed is less than 1,000 RPM. |
| Or |
| • | The throttle angle is less than 98 percent when the engine speed is more than 1,000 RPM. |
Conditions for Setting the DTC
The PCM detects that the MAP sensor voltage is more than 4.8 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-Engine Controls? | -- | Go to Step 2 | |||||||
2 |
Is DTC P0641 also set? | -- | Go to DTC P0641 | Go to Step 3 | ||||||
3 |
Is the voltage more than the specified value? | 4.8 V | Go to Step 5 | Go to Step 4 | ||||||
4 |
Does the DTC fail this ignition? | -- | Go to Step 5 | Go to Intermittent Conditions | ||||||
5 | Inspect the manifold absolute pressure (MAP) sensor vacuum source for the following conditions:
Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 6 | ||||||
6 | Monitor the Diagnostic Trouble Code (DTC) Information with the scan tool. Is DTC P0651 also set? | -- | Go to Step 10 | Go to Step 7 | ||||||
7 | Test for an intermittent and for a poor connection at the MAP sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 8 | ||||||
8 |
Is the voltage less than the specified value? | 0.55 V | Go to Step 9 | Go to Step 11 | ||||||
Is the voltage more than the specified value? | 0.2 V | Go to Step 12 | Go to Step 14 | |||||||
10 |
Is the voltage less than the specified value? | 0.55 V | Go to DTC P0651 | Go to Step 11 | ||||||
11 |
Important: The MAP sensor may have been damaged if the circuit was shorted to a voltage source. 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 in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 15 | ||||||
12 | Test the low reference circuit between the PCM and the MAP sensor for high resistance or for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 13 | ||||||
13 | Test for an intermittent and for a poor connection at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 16 | Go to Step 15 | ||||||
14 | Replace the MAP sensor. Refer to Manifold Absolute Pressure Sensor Replacement . Did you complete the replacement? | -- | Go to Step 16 | -- | ||||||
15 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 16 | -- | ||||||
16 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 17 | ||||||
17 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |||||||
