Circuit Description
The manifold absolute pressure (MAP) sensor responds to changes in the intake manifold pressure, vacuum. The MAP signal voltage to the engine control module (ECM) varies from below 2 volts at idle, high vacuum, to above 4 volts with the key in the ON position, engine not running, or at wide open throttle (WOT), low vacuum.
A speed density method of determining engine load is used. This is calculated using inputs from the MAP sensor, the RPM (58X), and the intake air temperature (IAT) sensor. The MAP sensor is the main sensor used in this calculation, and measuring engine load is its main function.
The MAP sensor is also used to determine manifold pressure changes while the linear exhaust gas recirculation (EGR) flow test diagnostic is being run. Refer to DTC P0401 . This determines the engine vacuum level for some other diagnostics and determines barometric pressure (BARO). The ECM compares the MAP sensor signal to calculated MAP based on throttle position (TP) and various other engine load factors. If the ECM detects a MAP signal voltage that is intermittently below the calculated value, diagnostic trouble code (DTC) P1107 will set.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P1107 Manifold Absolute Pressure (MAP) Sensor Circuit Intermittent Low Voltage
Conditions for Running the DTC
| • | DTCs P0122, P0123, P1121, and P1122 are not set. |
| • | The TP sensor is more than or equal to 0 percent if the engine speed is less than or equal to 1,500 RPM. |
| • | The TP sensor is more than 10 percent if the engine speed is more than 1,500 RPM. |
| • | The ignition 1 voltage is more than 11.5 volts. |
| • | DTC P1107 runs continuously once the above conditions are met. |
Conditions for Setting the DTC
The ECM detects that the MAP sensor is less than 12 kPa intermittently for more than 60 seconds.
Action Taken When the DTC Sets
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | The ECM will store conditions which were present when the DTC was set as Failure Records data only. |
| • | This information will not be stored in the Freeze Frame data. |
Conditions for Clearing the MIL/DTC
| • | A history DTC will clear after 40 consecutive warm-up cycles without a fault. |
| • | DTCs can be cleared by using the scan tool. |
| • | Disconnect the ECM battery feed for more than 10 seconds. |
Diagnostic Aids
Check for the following conditions:
| • | Leaking or plugged vacuum supply line to the MAP sensor |
| • | Inspect ECM harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal-to-wire connection. |
| • | Inspect the wiring harness for damage. If the harness appears to be OK, observe the MAP display on the scan tool while moving the connectors and wiring harnesses related to the sensor. A change in the display will indicate the location of the fault. |
Reviewing the Failure Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.
Test Description
The number below refers to the step number on the diagnostic table.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Controls Connector End Views | |||
1 | Did you perform the Diagnostic System Check - Engine Controls? | Go to Step 2 | |
2 |
Is DTCs P0107 also set? | Go to DTC P0107 | Go to Step 3 |
Observe the manifold absolute pressure (MAP) sensor parameter with a scan tool while moving the MAP sensor connector and the engine control module (ECM) connector. Refer to Inducing Intermittent Fault Conditions in Wiring Systems. Does the scan tool indicate an abrupt change in value? | Go to Step 5 | Go to Step 4 | |
Observe the MAP sensor parameter with a scan tool while moving the wiring harness between the MAP sensor and the ECM. Refer to Inducing Intermittent Fault Conditions in Wiring Systems. Does the scan tool indicate an abrupt change in value? | Go to Step 6 | Go to Intermittent Conditions | |
5 | Repair the connector/terminal as necessary. Refer to Connector Repairs in Wiring Systems. Did you complete the repair? | Go to Step 7 | -- |
6 | Repair the harness/wiring as necessary. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 7 | -- |
7 |
Did the DTC fail this ignition? | Go to Step 2 | Go to Step 8 |
8 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | System OK | |
