Circuit Description
The manifold absolute pressure (MAP) sensor responds to pressure changes in the intake manifold. The pressure changes occur based on the engine load. The MAP sensor has the following circuits:
| • | 5-volt reference circuit |
| • | Low reference circuit |
| • | MAP sensor signal circuit |
The powertrain control module (PCM) supplies 5 volts to the MAP sensor on the 5-volt reference circuit. The PCM also provides a ground on the low reference circuit. The MAP sensor provides a signal to the PCM on the MAP sensor signal circuit which is relative to the pressure changes in the manifold. The PCM should detect a low signal voltage at a low MAP, such as during an idle or a deceleration. The PCM should detect a high signal voltage at a high MAP, such as the ignition is ON, with the engine OFF, or at a wide open throttle (WOT). The MAP sensor is also used in order to determine the barometric pressure (BARO). This occurs when the ignition switch is turned ON, with the engine OFF. The BARO reading may also be updated whenever the engine is operated at WOT. The PCM monitors the MAP sensor signal for voltage outside of the normal range.
The PCM calculates a predicted value for the MAP sensor based on throttle position and engine speed. The PCM then compares the predicted value to the actual MAP sensor signal. DTC P0106 will set if the MAP sensor signal is not within the predicted range.
Conditions for Running the DTC
| • | DTCs P0121, P0122, or P0123 are not set. |
| • | Any change in the IAC position is less than 15 counts. |
| • | The engine speed is at least 1000 RPM, but less than 4000 RPM. |
| • | The engine speed variation is no more than 125 RPM. |
| • | The throttle position (TP) sensor variation is no more than 4 percent. |
| • | Any change in EGR position is less than 10 g/s. |
| • | The TCC state is unchanged for 3 seconds. |
| • | The brake switch is off for 3 seconds. |
| • | The A/C clutch state is unchanged for 2 seconds. |
| • | The traction control is not active. |
| • | The engine overtemp protection is not active. |
Conditions for Setting the DTC
The actual MAP sensor signal is not within the predicted range for at least 1 second.
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. |
| • | The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
| • | A current DTC, Last Test Failed, clears when the diagnostic runs and passes. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
| • | Clear the MIL and the DTC with a scan tool. |
Diagnostic Aids
| • | Inspect for the following conditions: |
| - | Restrictions in the MAP sensor vacuum source |
| - | A missing or damaged MAP sensor seal |
| - | Disconnected, damaged, or incorrectly routed vacuum hoses |
| - | Intake manifold vacuum leaks |
| - | Vacuum leaks at the throttle body |
| • | If an intermittent condition exists, refer to Intermittent Conditions . |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step tests the MAP sensor's ability to correctly indicate barometric pressure.
-
This step tests the MAP sensor's ability to respond to an increase in engine vacuum.
-
This step tests for a proper MAP sensor voltage with an applied vacuum.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |
2 |
Does the throttle angle move steadily and completely from the first value to above the second value? | 0% 98% | Go to Step 3 | Go to DTC P0121 |
Is the difference between the vehicles less than the specified value? | 3 kPa (0.43 psi) | Go to Step 4 | Go to Step 8 | |
4 |
Does the MAP sensor value change? | -- | Go to Step 5 | Go to Step 8 |
Does the scan tool indicate that the MAP sensor is operating normally? | -- | Go to Step 6 | Go to Step 16 | |
Observe the MAP sensor pressure with 20 inch HG of vacuum applied to the MAP sensor. Does the scan tool indicate that the MAP sensor pressure is less than the specified value? | 34 kPa (4.9 psi) | Go to Step 7 | Go to Step 8 | |
7 | Disconnect the MAP sensor from the hand vacuum pump. Does the MAP sensor pressure return to the original value that was observed in step 3? | -- | Go to Diagnostic Aids | Go to Step 16 |
8 |
Does the scan tool indicate that the MAP sensor voltage is more than the specified value? | 0.5 V | Go to Step 15 | Go to Step 9 |
9 | Connect a 3-amp fused jumper wire between the 5-volt reference circuit of the MAP sensor and the signal circuit of the MAP sensor. Does the scan tool indicate that the MAP sensor voltage is near the specified value? | 5 V | Go to Step 10 | Go to Step 14 |
10 |
Does the voltage measure more than the specified value? | 5.2 V | Go to Step 12 | Go to Step 11 |
11 | Probe the low reference circuit of the MAP sensor with a test lamp that is connected to battery positive voltage. Does the test lamp illuminate? | -- | Go to Step 16 | Go to Step 13 |
12 | Test the 5-volt reference circuit of the MAP sensor for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 20 | Go to Step 17 |
13 | Test the low reference circuit of the MAP sensor for high resistance. Refer to Testing for Continuity and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 20 | Go to Step 17 |
14 | Test the 5-volt reference and the signal circuit of the MAP sensor for high resistance. Refer to Testing for Continuity and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 20 | Go to Step 17 |
15 | Test the signal circuit of the MAP sensor for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 20 | Go to Step 17 |
16 | Inspect the MAP sensor for poor connections. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 20 | Go to Step 18 |
17 | Inspect the PCM for poor connections. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 20 | Go to Step 19 |
18 | Replace the MAP sensor. Refer to Manifold Absolute Pressure Sensor Replacement . Did you complete the replacement? | -- | Go to Step 20 | -- |
19 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 20 | -- |
20 |
Does the DTC run and pass? | -- | Go to Step 21 | Go to Step 2 |
21 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |
