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 engine control module (ECM) supplies 5 volts to the MAP sensor on the 5-volt reference circuit. The ECM 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 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 MAP sensor contains the following circuits:
| • | A 5-volt reference |
| • | A low reference |
| • | A MAP sensor signal |
If the ECM detects that the MAP sensor pressure/voltage is too high, this DTC 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 P0122 and P0123 are not set. |
| • | The ignition 1 voltage is greater than 10 volts. |
| • | The engine speed is greater than 700 RPM. |
| • | The MAP is greater than 95 kPa (14 psi). |
| • | DTC P0108 runs continuously when the above conditions are met. |
Conditions for Setting the DTC
The ECM detects a short to voltage on the signal circuit of the MAP sensor.
Action Taken When the DTC Sets - European Emissions
| • | The malfunction indicator lamp (MIL) will illuminate. |
| • | The ECM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and Failure Records buffers. |
| • | A history DTC is stored. |
| • | The ECM will substitutes a fixed MAP value and use TP to control the fuel delivery. The scan tool will not show defaulted. |
Action Taken When the DTC Sets - Non European Emissions
| • | The malfunction indicator lamp (MIL) will illuminate. |
| • | The ECM will substitute a fixed MAP value and use TP to control the fuel delivery. The scan tool will not show defaulted. |
Conditions for Clearing the MIL/DTC - European Emissions
| • | The MIL will turn OFF after 4 consecutive ignition cycles in which the diagnostic runs without a fault. |
| • | A history DTC will clear after 40 consecutive warm-up cycles without a fault. |
| • | DTCs can be cleared by using the scan tool. |
| • | Disconnect the ECM battery feed for more than 10 seconds. |
Conditions for Clearing the MIL/DTC - Non European Emissions
| • | The MIL will turn OFF when the diagnostic runs and passes. |
| • | DTCs can be cleared by using the scan tool. |
| • | Disconnect the ECM battery feed for more than 10 seconds. |
Test Description
The numbers below refer to the step numbers in the diagnostic table.
-
This step determines if there is a short to voltage or an open condition in the circuits.
-
This step determines if the circuit has a short to voltage. A short to voltage can cause more than one DTC to set.
Step | Action | Values | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connect End View Reference: Engine 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 |
Did DTC P0108 fail this ignition? | -- | Go to Step 4 | Go to Step 3 | ||||||
3 |
Does the DTC fail this ignition? | -- | Go to Step 4 | Go to Intermittent Conditions | ||||||
Does the scan tool indicate that the MAP sensor parameter is less than the specified value? | 50 kPa | Go to Step 5 | Go to Step 7 | |||||||
5 | Measure the voltage from the 5-volt reference circuit of the MAP sensor to a good ground with a DMM. Does the voltage measure more than the specified value? | 5.2 V | Go to Step 9 | Go to Step 6 | ||||||
6 | Measure the resistance between the low reference circuit of the MAP sensor and the engine control module (ECM) housing with a DMM. Is the resistance less than the specified value? | 5 ohms | Go to Step 10 | Go to Step 8 | ||||||
7 | Test the signal circuit of 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 14 | Go to Step 11 | ||||||
8 |
Important: The engine control module (ECM) and MAP sensor may be damaged if the circuit is shorted to battery positive voltage. Test the low reference circuit of the MAP sensor for the following conditions:
Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 14 | Go to Step 11 | ||||||
|
Important: The 5-volt reference circuits are internally and externally connected at the ECM. Other component DTCs may be set. If other DTCs are set, review the electrical schematic and diagnose the applicable circuits and components. Test the 5-volt reference circuit of 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 14 | Go to Step 11 | |||||||
10 | 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 14 | Go to Step 12 | ||||||
11 | Test for an intermittent and for a poor connection at the engine control module (ECM). 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 14 | Go to Step 13 | ||||||
12 | Replace the MAP sensor. Refer to Manifold Absolute Pressure Sensor Replacement . Did you complete the replacement? | -- | Go to Step 14 | -- | ||||||
13 | Replace the ECM. Refer to Engine Control Module Replacement . Did you complete the replacement? | -- | Go to Step 14 | -- | ||||||
14 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 15 | ||||||
15 | Are there any DTCs that have not been diagnosed? | -- | System OK | |||||||
