Circuit Description
The manifold absolute pressure (MAP) sensor responds to pressure changes in the intake manifold. The pressure changes occur based on the engine load. The MAP sensor has the following circuits:
| • | 5-volt reference circuit |
| • | Low reference circuit |
| • | MAP sensor signal circuit |
The engine control module (ECM) supplies 5 volts to the MAP sensor on the 5-volt reference circuit. The ECM also provides a ground on the low reference circuit. The MAP sensor provides a signal to the ECM on the MAP sensor signal circuit which is relative to the pressure changes in the manifold. The ECM should detect a low signal voltage at a low MAP, such as during an idle or a deceleration. The ECM should detect a high signal voltage at a high MAP, such as the ignition is ON, with the engine OFF, or at a wide open throttle (WOT). The MAP sensor is also used in order to determine the barometric pressure (BARO). This occurs 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 ECM monitors the MAP sensor signal for voltage outside of the normal range.
If the ECM 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, P0123, P0220, P0222, P0223, P0641, P0651, P1516, P2101, P2119, P2135, P2176, 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 0-4 minutes. |
| • | The accelerator pedal angle is less than 1 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. |
| • | The above conditions are present for 4 seconds. |
| • | DTC P0108 runs continuously when the above conditions are met. |
Conditions for Setting the DTC
The ECM detects that the MAP sensor voltage is more than 4.9 volts for more than 3.2 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. |
Diagnostic Aids
| • | Inspect for any vacuum leaks. |
| • | This DTC may set as the result of a misfire. |
| • | This DTC may set as the result of improper tension or alignment of the timing chain. |
| • | If this DTC is determined to be intermittent, refer to Testing for Intermittent Conditions and Poor Connections . |
Step | Action | Values | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views | ||||||||||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |||||||||
2 | Attempt to start the engine. Does the engine start and run? | -- | Go to Step 3 | Go to Step 4 | ||||||||
3 | Observe the manifold absolute pressure (MAP) sensor parameter with a scan tool. Is the voltage more than the specified value? | 4.9 V | Go to Step 6 | Go to Step 5 | ||||||||
4 |
Is the voltage more than the specified value? | 4.9 V | Go to Step 6 | Go to Diagnostic Aids | ||||||||
5 |
Does the DTC fail this ignition? | -- | Go to Step 6 | Go to Diagnostic Aids | ||||||||
6 | Inspect for the following conditions:
Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 7 | ||||||||
7 |
Is DTC P0641 also set? | -- | Go to Step 10 | 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 13 | ||||||||
10 |
Is the voltage less than the specified value? | 0.1 V | Go to DTC P0641 | Go to Step 11 | ||||||||
11 | Test the MAP sensor signal circuit between the engine control module (ECM) 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 17 | Go to Step 16 | ||||||||
12 | Test the low reference circuit between the ECM and the MAP sensor for high resistance or for an open. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 14 | ||||||||
13 | Inspect 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 17 | Go to Step 15 | ||||||||
14 | Inspect for an intermittent and for a poor connection at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 17 | Go to Step 16 | ||||||||
15 | Replace the MAP sensor. Refer to Manifold Absolute Pressure Sensor Replacement . Did you complete the replacement? | -- | Go to Step 17 | -- | ||||||||
16 | Replace the ECM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 17 | -- | ||||||||
17 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 18 | ||||||||
18 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |||||||||
