Circuit Description
VIN K
The manifold absolute pressure (MAP) sensor responds to changes in the intake manifold pressure, which gives an indication of the engine load. The MAP sensor has a 5-volt reference circuit, a low reference circuit, and a signal circuit. The powertrain control module (PCM) supplies 5 volts to the MAP sensor on the 5-volt reference circuit, and provides a ground on the low reference circuit. The MAP sensor provides a signal to the PCM on the MAP sensor signal circuit, which is relative to the pressure changes in the manifold. With low MAP, such as during idle or deceleration, the PCM should detect a low MAP sensor signal voltage. With high MAP, such as during ignition ON, engine OFF, or wide open throttle (WOT), the PCM should detect a high MAP sensor signal voltage. This MAP sensor will indicate pressure between 10-104 kPa. The MAP sensor is also used in order to calculate the barometric pressure (BARO) when the ignition switch is turned ON, with the engine OFF. The BARO reading may also be updated whenever the engine is operated at WOT. 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.
VIN 1
The MAP sensor responds to changes in intake manifold pressure which gives an indication of the engine load. The MAP sensor has a 5-volt reference circuit, a low reference circuit, and a signal circuit. The PCM supplies 5 volts to the MAP sensor on the 5-volt reference circuit, and provides a ground on the low reference circuit. The MAP sensor provides a signal to the PCM on the MAP sensor signal circuit, which is relative to the pressure changes in the manifold. With low MAP, such as during idle or deceleration, the PCM should detect a low MAP sensor signal voltage. With high MAP, such as WOT, the PCM should detect a high MAP sensor signal voltage. This MAP sensor will indicate pressure between 8-208 kPa. The MAP sensor is also used in order to calculate the BARO when the ignition switch is turned ON, with the engine OFF. 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.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0108 Manifold Absolute Pressure (MAP) Sensor Circuit High Voltage
Conditions for Running the DTC
VIN K
| • | DTCs P0121, P0122, P0123 are not set. |
| • | The engine has been running for a length of time that is determined by the start-up coolant temperature. 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 throttle angle is less than 2 percent when engine speed is less than 1,500 RPM. |
| OR |
| • | The throttle angle is less than 10 percent when the engine speed is more than 1,500 RPM. |
VIN 1
| • | DTCs P0121, P0122, P0123 are not set. |
| • | The engine has been running for a length of time that is determined by the start-up coolant temperature. 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 throttle angle is less than 2 percent when the engine speed is less than 900 RPM. |
| OR |
| • | The throttle angle is less than 30 percent when the engine speed is more than 900 RPM. |
Conditions for Setting the DTC
| • | The PCM detects that the MAP sensor signal voltage is more than 4.2 volts for 3 seconds. |
| • | This diagnostic runs continuously once the above conditions have been met. |
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. |
Diagnostic Aids
This DTC may set due to poor idle characteristics. A possible cause may be uncontrolled fueling due to an open or high resistance in the heated oxygen sensor (HO2S) 1 low signal circuit. Before replacing any component, ensure that this condition does not exist.
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: Engine Controls Connector End Views or Powertrain Control Module Connector End Views | ||||||||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |||||||
Does the TP sensor parameter increase steadily to more than the first specified value, then decrease steadily returning to less than the second specified value? | 98% 1% | Go to Step 3 | Go to DTC P0121 | |||||||
3 |
Is the voltage more than the specified value? | 4.2 V | Go to Step 5 | Go to Step 4 | ||||||
4 |
Did 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 18 | Go to Step 6 | ||||||
6 | Monitor the DTC information with the scan tool. Is DTC P0641 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 . Did you find and correct the condition? | -- | Go to Step 18 | Go to Step 8 | ||||||
8 |
Is the voltage less than the specified value? | 0.1 V | Go to Step 9 | Go to Step 11 | ||||||
9 |
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? | 0.1 V | Go to DTC P0641 | Go to Step 11 | ||||||
11 |
Important: Disconnecting the powertrain control module (PCM) may eliminate the short during testing. 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 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 18 | Go to Step 15 | ||||||
12 | Test the low reference circuit between the PCM and the MAP sensor for 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 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 . Did you find and correct the condition? | -- | Go to Step 18 | Go to Step 17 | ||||||
14 | Test the heated oxygen sensor (HO2S) 1 low signal circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 18 | Go to Step 16 | ||||||
15 | Test the HO2S 1 low signal circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 18 | Go to Step 17 | ||||||
16 | Replace the MAP 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 in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 18 | -- | ||||||
18 |
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? | -- | System OK | |||||||
