Circuit Description
The Manifold Absolute Pressure sensor is a sensor that changes resistance based upon manifold vacuum. The PCM provides a 5 volt reference and ground. The MAP sensor signal varies between ground and 5 volts as manifold vacuum varies. As MAP decreases, voltage decreases (low engine load, high vacuum). As MAP increases, voltage increases (high engine load, low vacuum). The PCM uses the MAP sensor values as an indicator of engine load. If the MAP sensor signal goes high such as when the signal line is shorted to voltage or the MAP sensor is shorted internally, DTC P0108 will set.
Conditions for Setting the DTC
Test Conditions
| • | DTCs P0122 and P0123 not set. |
| • | Engine running. |
| • | Throttle angle 20.5 degrees or less. |
Failure Condition
The MAP sensor reading has been 5.06 volts or higher.
Action Taken When the DTC Sets
| • | PCM turns ON the SERVICE EMISSION SYSTEM message. |
| • | PCM disables long term fuel trim. |
| • | PCM uses a substitute MAP value based on engine RPM and throttle angle. |
| • | PCM uses 92.2 kPa for barometric pressure. |
| • | PCM disables Evaporative Emission (EVAP) control solenoid. |
| • | PCM disables torque management. |
| • | Transaxle shift adapts are maintained at current levels. |
| • | The PCM will illuminate the malfunction indicator lamp (MIL) when the diagnostic runs and fails. |
| • | The PCM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The PCM will turn the MIL OFF after three consecutive drive trips that the diagnostic runs and does not fail. |
| • | A Last Test Failed (current) DTC will clear when the diagnostic runs and does not fail. |
| • | A History DTC will clear after forty consecutive warm-up cycles with no failures of any emission related diagnostic test. |
| • | Use a scan tool to clear DTCs. |
| • | Interrupting PCM battery voltage may or may not clear DTCs. This practice is not recommended. Refer to Clearing Diagnostic Trouble Codes in PCM Description and Operation. |
Diagnostic Aids
DTC P0108 could be set during an engine backfire, which would cause a rapid increase in MAP value. Check P0108 snapshot data for additional information.
Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table.
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If MAP value is greater than 102 kPa, a MAP sensor circuit problem must be present.
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If MAP value is less than 16 kPa, the fault is the MAP sensor or the reference voltage is higher than 5.06 volts.
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A high voltage reading on the 5 volt reference circuit could be caused by a short to voltage on another 5 volt reference circuit, some 5V Ref. circuits are shared inside the PCM, or battery voltage bleeding onto the 5 volt reference circuit as in a defective Linear EGR Valve.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | Go to A Powertrain On Board Diagnostic (OBD) System Check | |
Is the value greater than the value specified? | 102 kPa | Fault not present, Go to DTC P0106 Manifold Absolute Pressure (MAP) System Performance | ||
Disconnect the MAP sensor. Is the MAP sensor value less than the value specified? | 16 kPa | |||
4 | Using DMM J 39200 measure the voltage to ground at MAP sensor connector terminal C. Is the voltage higher than the value specified? | 5.50 volts | ||
5 | Using DMM J 39200 measure the voltage to ground at MAP sensor connector terminal B. Is the voltage higher than the value specified? | 0.5 volts | ||
6 | Repair short to voltage on Map Sensor Signal circuit. Is the repair complete? | -- | Go to Powertrain Control Module Diagnosis for Verify Repair | -- |
Repair the short to voltage on the 5 Volt Reference circuit. Refer to Test Descriptions. Is the repair complete? | -- | Go to Powertrain Control Module Diagnosis for Verify Repair | -- | |
8 |
Was terminal contact repaired? | -- | Go to Powertrain Control Module Diagnosis for Verify Repair | |
9 | Replace the MAP sensor. Refer to MAP Sensor Replacement . Is the replacement complete? | -- | Go to Powertrain Control Module Diagnosis for Verify Repair | -- |
10 |
Was terminal contact repaired? | -- | Go to Powertrain Control Module Diagnosis for Verify Repair | |
11 | Replace the PCM. Refer to PCM Replacement/Programming . Is the replacement complete? | -- | Go to Powertrain Control Module Diagnosis for Verify Repair | -- |
