Circuit Description
The PCM uses the Manifold Absolute Pressure (MAP) sensor output voltage in order to assist in controlling the fuel delivery and the ignition timing. The PCM supplies a 5 volt reference signal voltage and a ground circuit to the MAP sensor. As the manifold pressure changes, the output voltage of the sensor also changes. By monitoring the sensor output voltage, the PCM knows the manifold pressure. A lower pressure (low voltage) output voltage will read between 1.0 to 1.5 volts at idle. While higher pressure (high voltage) output voltage will read between 4.5 to 4.8 at Wide Open Throttle (WOT). The PCM uses the MAP sensor to record the barometric pressure during an engine start up and at wide open throttle. This allows the PCM to make adjustments for different altitudes.
Conditions for Setting the DTC
| • | The engine speed is less than 1000 RPM. |
| Or |
| • | The engine speed is greater than 1000 RPM and the Throttle Position (TP) sensor is greater than 15%. |
| • | The MAP is less than 11.8 kPa. |
| • | The above conditions are met for at least 6.25 seconds. |
| • | DTC P0122 or P0123 is not set. |
Action Taken When the DTC Sets
| • | The Malfunction Indicator Lamp (MIL) illuminates. |
| • | The PCM records the operating conditions at the time the diagnostic fails. The Freeze Frame and Failure Records buffers stores this information. |
| • | A history DTC is stored. |
| • | The PCM substitutes a fixed MAP value. The PCM uses the throttle position in order to control the fuel delivery. The scan tool will not show the defaulted value. |
| • | The vehicle will opeerate in Open Loop when the vehicle is under 5 mph. The vehicle will operate in Closed Loop when the vehicle is over 5 mph. |
Conditions for Clearing the MIL/DTC
| • | The malfunction indicator lamp (MIL) will turn OFF after 3 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. |
| • | Use a scan tool to clear the DTCs. |
Diagnostic Aids
Important: After repairs use the scan tool Fuel Trim Reset function in order to reset the long term fuel trim to 128 (0%).
| • | With the ignition ON and the engine OFF, the manifold pressure is equal to the atmospheric pressure and the signal voltage will be high. The PCM uses this information as an indication of the altitude of the vehicle. The comparison of this reading with a known good vehicle with the same sensor is a good way to check the accuracy of a suspect sensor. Readings should be the same ± 0.4 volt. |
| • | Whenever a DTC P0107 is intermittent, refer to the Driveability Symptoms Tables or to Symptoms for further diagnosis. |
Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table.
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The Powertrain OBD System Check prompts the technician to complete some basic checks and store the freeze frame and failure records data on the scan tool if applicable. This creates an electronic copy of the data taken when the malfunction occurred. The information is then stored in the scan tool for later reference.
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This step determines if DTC P0107 is the result of a hard malfunction or an intermittent condition.
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Jumpering harness terminals B to C (signal circuit to 5 volts) will determine if the sensor is malfunctioning or if there is a problem with the PCM or wiring.
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The scan tool may not display 5.0 volts. The important thing is that the PCM recognizes the voltage as more than 4.0 volts, indicating that the PCM and CKT 432 are OK. A test light that illuminates indicates a short to ground in the signal circuit.
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A short to ground in the 5 volt reference circuit could also set additional DTCs.
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The replacement PCM must be programmed and the crankshaft position variation procedure must be performed. Refer to the latest Techline procedure for PCM reprogramming and also refer to for the Crankshaft Position Variation Procedure
Step | Action | Value(s) | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | |||||||||
With engine idling, install a scan tool. Does the scan tool display MAP voltage below the specified value? | 0.25V | |||||||||
Does the MAP voltage read more than the specified value? | 4.7V | |||||||||
4 |
Does the scan tool display MAP voltage below the specified value? | 0.25V | Go to Diagnostic Aids | |||||||
5 | Inspect the MAP Sensor harness electrical connector terminals for the following conditions:
Was a problem found? | -- | ||||||||
Does the scan tool read over the specified value? | 4.0V | |||||||||
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Important: The Powertrain Control Module (PCM) uses a single 5.0 volt power supply to supply power to all the engine control components. If one component shorts its 5.0 volt reference circuit to ground or battery voltage, the other 5.0 volt reference circuits will also have a low or high voltage. Check the MAP sensor 5 volt reference circuit for an open or short to ground. Was a problem found? | -- | |||||||||
8 | Repair the connection terminal(s) as necessary. Is the action complete? | -- | -- | |||||||
9 | Replace the MAP sensor. Refer to Manifold Absolute Pressure Sensor Replacement . Is the action complete? | -- | -- | |||||||
10 | Repair the MAP sensor 5 volt reference circuit. Is the action complete? | -- | -- | |||||||
Replace the PCM. Refer to Powertrain Control Module Replacement . Is the action complete? | -- | -- | ||||||||
12 | Check the MAP sensor signal circuit for the following conditions:
Was a problem found? | -- | ||||||||
13 | Repair the MAP sensor signal circuit. Is the action complete? | -- | -- | |||||||
14 |
Does the scan tool indicate that this diagnostic ran and passed? | -- | ||||||||
15 | Check if any additional DTCs are set. Are any DTCs displayed that have not been diagnosed? | -- | Go to the Applicable DTC table | System OK |
