Circuit Description
The Manifold Absolute Pressure (MAP) sensor responds to changes in intake manifold pressure. The PCM supplies a 5 volt reference and a ground for the MAP sensor. The MAP sensor provides a signal to the PCM relative to pressure changes in the manifold. The MAP sensor signal voltage to the PCM varies from below 2 volts at idle (low manifold absolute pressure - high vacuum) to above 4 volts with the key ON, engine not running or at wide-open throttle (high manifold absolute pressure - low vacuum). The PCM monitors the MAP signals for voltages outside the normal range of the MAP sensor. If the PCM detects a MAP signal voltage that is excessively high, DTC P0108 will be set.
VIN 1
The Manifold Absolute Pressure (MAP) sensor responds to changes in intake manifold pressure. The PCM supplies a 5 volt reference and a ground for the MAP sensor. The MAP sensor circuit provides a signal to the PCM relative to pressure changes in the manifold. With the key ON, engine not running, the MAP sensor signal voltage to the PCM varies between 1.5 to 2.5 volts. With the engine running, the MAP sensor voltage to the PCM varies from below 2 volts at idle (low manifold absolute pressure - high vacuum) to above 4 volts at wide-open throttle (high manifold absolute pressure - low vacuum). The PCM monitors the MAP signals for voltages outside the normal range of the MAP sensor. If the PCM detects a MAP signal voltage that is excessively high, DTC P0108 will be set.
Conditions for Running the DTC
| • | No ECT sensor, MAF sensor or VSS DTCs present. |
| • | The engine has been running for over 10 seconds. |
| • | Vehicle speed is greater than 25 mph. |
Conditions for Setting the DTC
| • | IAT signal voltage indicates an intake air temperature greater than 134°C (274°F). |
| • | The above conditions are present for at least 20 seconds. |
Action Taken When the DTC Sets
| • | The PCM will illuminate the MIL during the second consecutive trip in which the diagnostic test has been run and failed. |
| • | The PCM will store conditions which were present when the DTC set as Freeze Frame and Fail Records data. |
Conditions for Clearing the MIL/DTC
| • | The PCM will turn the MIL OFF during the third consecutive trip in which the diagnostic has been run and passed. |
| • | The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction. |
| • | The DTC can be cleared by using the scan tool Clear Info function or by disconnecting the PCM battery feed. |
Diagnostic Aids
Check for the following conditions:
| • | Poor connection at the PCM. |
| Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection. |
| • | Damaged harness. |
| Inspect the wiring harness for damage. If the harness appears to be OK, observe the IAT display on the scan tool while moving connectors and wiring harnesses related to the IAT sensor. A change in the IAT display will indicate the location of the malfunction. |
| • | Skewed or mis-scaled IAT Sensor. |
| Refer to Temperature Versus Resistance . |
If DTC P0112 cannot be duplicated, the information included in the Fail Records data can be useful in determining vehicle mileage since the DTC was last set.
Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table:
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Verifies that the malfunction is present
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If DTC P0112 can be repeated only by duplicating the Fail Records conditions, refer to the Temperature Versus Resistance . The table may be used to test the IAT sensor at various temperatures to evaluate the possibility of a shifted sensor that may be shorted above or below a certain temperature. If this is the case, replace the IAT sensor.
If the IAT sensor appears to be OK, the malfunction is intermittent; refer to Diagnostic Aids.
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This vehicle is equipped with a PCM which utilizes an Electrically Erasable Programmable Read Only Memory (EEPROM). When the PCM is being replaced, the new PCM must be programmed.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | ||
Is Intake Air Temp. greater than specified value? | 130°C (266°F) | |||
Does the scan tool indicate DTC P0112 failed this ignition? | -- | Go to Diagnostic Aids | ||
4 |
Is Intake Air Temperature less than the specified value? | -38°C (-36°F) | ||
5 |
Is the IAT sensor signal circuit shorted to ground? | -- | ||
6 | Replace the IAT Sensor. Refer to Intake Air Temperature Sensor Replacement . Is action complete? | -- | -- | |
7 | Repair the IAT sensor signal circuit. Refer to Wiring Repairs . Is action complete? | -- | -- | |
|
Important:: The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is action complete? | -- | -- | ||
9 |
Does the scan tool indicate DTC P0112 failed this ignition? | -- | System OK |
