Circuit Description
The Manifold Absolute Pressure (MAP) sensor responds to changes in the intake manifold pressure (vacuum). A 5 volt reference is applied to the sensor on the 5 volt reference circuit. A variable resistor moves in relation to the manifold pressure and a voltage signal is sent back to the VCM on the MAP signal circuit. This voltage signal varies from 1.0-1.5 volts at closed throttle to 4.0-4.5 volts at wide open throttle (low vacuum). The VCM utilizes the MAP signal and throttle position in order to determine the correct amount of fuel delivered to the engine. This DTC is a type A DTC.
Conditions for Setting the DTC
| • | No TP sensor DTCs |
| • | The engine is running |
| • | Throttle Position is at least 0% when engine speed is no more than 1000 RPM (800 RPM for 7.4L) |
| • | Throttle Position is at least 10.1% (12.5 for 7.4L) when engine speed is greater than 1000 RPM (800 RPM for 7.4L) |
| • | The MAP voltage is less than 0.25 Volts |
Action Taken When the DTC Sets
The VCM turns ON the MIL when DTC P0107 is reported and 1 failure has occurred. The VCM substitutes a calculated value for the MAP sensor value so an acceptable driving condition is maintained.
Conditions for Clearing the MIL or DTC
| • | The control module turns OFF the MIL after 3 consecutive drive trips when the test has run and passed. |
| • | A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles. A warm-up cycle occurs when the coolant temperature has risen 22°C (40°F) from the startup coolant temperature and the engine coolant reaches a temperature that is more than 70°C (158°F) during the same ignition cycle. |
| • | Use a scan tool in order to clear the DTCs. |
Diagnostic Aids
An intermittent open in the MAP sensor signal circuit or the 5 volt reference circuit will result in a DTC P1107.
With the ignition ON and the engine OFF, the manifold pressure is equal to the atmospheric pressure with the signal voltage high. The VCM uses this information as an indication of the altitude of the vehicle.
Comparison of this reading with a known good vehicle using the same sensor is a good way to check the accuracy of a suspect sensor. Readings should be the same ±0.4 volt.
Important: The electrical connector must remain securely fastened.
Important: After removing the MAP sensor from the intake manifold, replace the MAP Sensor to intake manifold seal.
Remove the MAP sensor. Twist the sensor by hand (only) in order to check for intermittent connections. Output changes greater than 0.1 volt indicates a bad connector or connection.Test Description
The numbers below refer to the step numbers on the diagnostic table.
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This step determines if DTC P0107 is the result of a hard failure or an intermittent condition.
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By jumping the 5 volt reference to the signal circuit, this step determines if the sensor is at fault, or if there is a problem with the VCM or wiring.
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The scan tool may not display 5 volts. The important thing is that the VCM recognized the voltage as more than 4 volts, indicating that the VCM and MAP signal circuit are OK.
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The VCM terminals GR 12 and GR 27 are spliced together inside the VCM. When checking the 5 volt reference for a short to ground, both the 5 volt reference circuits and all the components on the 5 volt reference circuits must also be checked.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 |
Important: Before clearing the DTCs, use the scan tool in order to record the Freeze Frame and the Failure Records for reference. This data will be lost when the Clear DTC Information function is used. Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | Go to A Powertrain On Board Diagnostic (OBD) System Check | |
Does the scan tool display a MAP sensor voltage less than the specified value? | 0.25 V | |||
Does the scan tool display a MAP sensor voltage greater then the specified value? | 4.7 V | |||
Does the scan tool display a MAP sensor voltage greater the specified value? | 4.7 V | |||
5 | The DTC is intermittent. Are any additional DTCs stored? | -- | Go to The Applicable DTC Table. | Go to Diagnostic Aids |
6 | Check for a faulty connection at the MAP sensor. Was a problem found? | -- | ||
7 | Check for an open MAP sensor signal circuit. Was a problem found? | -- | ||
8 | Check the MAP sensor signal circuit for a short to ground. Was a problem found? | -- | ||
9 | Check for an open in the MAP sensor 5 volt reference circuit. Was a problem found? | -- | ||
Check for a short to ground in the MAP sensor 5 volt reference circuit. Was a problem found? | -- | |||
11 | Replace the MAP sensor. Refer to MAP Sensor Replacement (5.0L, 5.7L) for the 5.0L, 5.7L. Refer to MAP Sensor Replacement (7.4L) for the 7.4L. Is the action complete? | -- | -- | |
12 | Repair the circuit as necessary. Refer to Wiring Repairs in Electrical Diagnosis. Is the action complete? | -- | -- | |
13 | Replace the VCM. Important: When replacing the VCM, the new VCM will need to be programmed. Refer to VCM Replacement/Programming . Is the action complete? | -- | -- | |
14 |
Does the scan tool indicate that this diagnostic ran and passed? | -- | ||
15 | Use the scan tool in order to display the Capture Info and the Review Capture Info function. Are there any DTCs displayed that have not been diagnosed? | -- | Go to The Applicable DTC Table | System OK |
