The manifold absolute pressure (MAP) sensor is a transducer that varies resistance according to changes in intake manifold pressure (vacuum). The powertrain control module (PCM) measures the signal voltage from the MAP sensor which is a reduced value of the PCM 5 volt reference. The voltage ranges from 1-1.5 volts at idle (low pressure/high vacuum) to 4-4.5 volts at wide open throttle (high pressure/low vacuum). DTC P0108 sets when the MAP sensor signal voltage at the PCM is above the calibrated voltage value.
DTC Parameters
DTC P0108 will set if MAP sensor voltage is greater than 4.24 volts when:
| • | The condition exists for longer than 2 seconds. |
| • | the engine speed is less than 1600 RPM. |
| • | The throttle position (TP) angle is less than 2 percent. |
| • | No TP sensor DTCs have been set. |
OR
| • | The condition exists for longer than 2 seconds. |
| • | The engine speed is greater than 1600 RPM. |
| • | The TP angle is less than 10 percent. |
| • | No TP sensor DTCs have been set. |
DTC P0108 diagnostic runs continuously with engine running.
DTC P0108 is a type A DTC.
Diagnostic Aids
Important: If DTC P1635 is set, diagnose that first.
To locate an intermittent problem, use a scan tool to monitor MAP voltage with engine running. Wiggling the wires while watching for a change in MAP voltage, may locate the area where an open or short to voltage in the wiring could lie.
Important: Inaccurate readings will occur if resistance measurements are taken on a MAP sensor. The MAP sensor contains an internal amplifier circuit that requires applied voltage to function properly.
With ignition ON, engine OFF, the MAP reading should be the same as the barometric pressure reading. Compare it to the reading of a known good vehicle with the same sensor to determine the accuracy of the suspect sensor. Readings should be within 0.40 volts.
Refer to DTC P0105 for an Altitude versus MAP Voltage chart.
