P0108

Circuit Description
The Manifold Absolute Pressure (MAP) sensor is mounted to the top rear of the intake manifold. The MAP sensor measures the pressure changes within the intake manifold which is an indication of the engine load. The MAP sensor has a 5.0 volt reference, a ground, and a signal circuit.

The MAP sensor contains a diaphragm which changes the resistance based on pressure. When the manifold pressure is low (high vacuum) the sensor output voltage is low. When the manifold pressure is high (low vacuum) the sensor output voltage is high.

The MAP sensor voltage (depending on altitude) can range from 1.0-1.5 volts at idle (high vacuum) to 4.0-4.9 volts at wide open throttle (low vacuum).

When the PCM senses a signal voltage higher than the normal operating range of the sensor, this DTC sets.

Conditions for Running the DTC
^ No TP sensor DTCs set.
^ The engine is operating.
^ The TP sensor angle is less than 5% when the engine speed is no more than 1000 RPM.
OR
^ The TP sensor angle is less than 18% when engine speed is greater than 1000 RPM.

Conditions for Setting the DTC
^ The MAP sensor voltage is greater than 4.3 volts.
^ All conditions met for greater than 4.0 seconds.

Action Taken When the DTC Sets
^ The PCM illuminates the Malfunction Indicator Lamp on the second consecutive ignition cycle that the diagnostic runs and fails.
^ The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the PCM stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the PCM records the operating conditions at the time of the failure. The PCM writes the conditions to the Freeze Frame and updates the Failure records.

Conditions for Clearing the MIL/DTC
^ The PCM turns the MIL OFF after three consecutive ignition cycles that the diagnostic runs and does not fail.
^ A last test failed (current DTC) clears when the diagnostic runs and does not fail.
^ A History DTC clears after forty consecutive warm-up cycles, if this or any other emission related diagnostic does not report any failures.
^ Use a scan tool in order to clear the MIL/DTC.

Diagnostic Aids

Important: Remove any debris from the PCM connector surfaces before servicing the PCM. Inspect the PCM connector gaskets when diagnosing/replacing the PCM. Ensure that the gaskets are installed correctly. The gaskets prevent water intrusion into the PCM.

^ The following may cause an intermittent:
- Mis-routed harness
- Rubbed through wire insulation
- Broken wire inside the insulation
^ The PCM 5.0 volt reference circuits are internally connected within the PCM. If all the MAP sensor circuits are OK, inspect the EGR circuits for malfunctions.
^ For an intermittent, refer to Symptoms. Symptom Related Diagnostic Procedures

Test Description
The numbers below refer to the step numbers on the diagnostic table.
2. If DTCs P1635 and P1639 set at the same time, this indicates that the MAP sensor circuit is shorted to a voltage.
3. This step determines if the malfunction is present.
4. Using the Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame and/or Failure Records data can help determine how many miles since the DTC set. The Fail Counter and Pass Counter can also help determine how many ignition cycles the diagnostic reported a pass and/or a fail. Operate the vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature etc.) that you observed. This will isolate when the DTC failed. For any test that requires probing the PCM or component harness connectors, use the Connector Test Adapter Kit J 35616-A. Using this kit prevents any damage to the harness connector terminals.
5. The MAP sensor is located under the intake manifold sight shield. This step checks whether the signal circuit is shorted to a voltage. Re-install the intake manifold sight shield after the repairs are completed.
6. This step checks whether a ground circuit is available at the MAP sensor. For any test that requires probing the PCM or component harness connectors, use the Connector Test Adapter kit J 35616-A. Using this kit prevents damage to the harness connector terminals.
9. Remove the MAP sensor and check if vacuum is available to the sensor. Also, inspect the MAP sensor seal for nicks and cuts.