For 1990-2009 cars
Engine Controls Components
Engine Data Sensors
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice

### Circuit Description

The manifold absolute pressure (MAP) sensor measures the changes in the intake manifold pressure which result from engine load, or the intake manifold vacuum, and RPM changes, and converts these into a voltage output. The Powertrain Control Module (PCM) sends a 5 volt reference voltage 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 calculates the manifold pressure. A lower pressure, low voltage, output voltage will be approximately 1.0 to 1.5 volts at idle. Higher pressure, high voltage, output voltage will be approximately 4.5 to 4.8 volts at wide open throttle (WOT). The MAP sensor is also used to measure barometric pressure, allowing the PCM to make adjustments for different altitudes. The PCM uses the MAP sensor to control fuel delivery and ignition timing.

### Test Description

Number(s) below refer to the step number(s) on the Diagnostic Table.

Important: Be sure to use the same diagnostic test equipment for all measurements.

1. Applying 34 kPa (10 in of Hg) vacuum to the MAP sensor should cause the voltage to be 1.5 to 2.1 volts less than the voltage at Step 3. Upon applying vacuum to the sensor, the change in voltage should be instantaneous. A slow voltage change indicates a faulty sensor.

2. Check vacuum hose to sensor for leaking or restriction. Be sure that no other vacuum devices are connected to the MAP hose.

3. Notice: Make sure electrical connector remains securely fastened.

   Move sensor electrical connector by hand (only) while watching scan tool to check for intermittent connection. Output changes greater than 0.10 volt indicate a bad connection. If OK, replace sensor.

#### Manifold Absolute Pressure (MAP) Sensor Output Check

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check
2 | Install scan tool and check for MAP DTCs. Were any MAP DTCs set? | -- | Go to MAP DTC Tables | Go to Step 3
3 |

1. Turn the ignition switch ON, with the engine OFF.
2. Compare the MAP sensor reading with the reading of a known good vehicle.

Are the voltage readings between the 2 vehicles within the specified value?

± 0.4V

Go to Step 4

Go to Step 5

4 |

1. Disconnect and plug the vacuum source to the MAP sensor.
2. Connect a hand vacuum pump to the MAP sensor.
3. Note the MAP sensor voltage on the scan tool.
4. Apply the specified vacuum to the sensor and note the MAP sensor voltage on the scan tool.
5. Subtract the second voltage reading from the first voltage reading.

Is the difference greater than the second specified value?

10 in of Hg (1)

34 kPa 1.5V(2)

Go to Step 6

Go to Step 7

5 | Replace MAP sensor. Is the action complete? | -- | Go to Step 9 | --
6 | Check MAP sensor vacuum source for leakage or for a restriction and be sure that the vacuum source supplies the MAP sensor only. Was a problem found? | -- | Go to Step 8 | Go to Step 9
7 | Check MAP sensor electrical connector terminals and repair as necessary. Was a repair necessary? | -- | Go to Step 9 | Go to Step 5
8 | Repair leakage or restriction in MAP sensor vacuum source. Is the action complete? | -- | Go to Step 9 | --
9 | Operate vehicle within the conditions under which the original symptom was noted. Does the system now operate properly? | -- | System OK | Go to Step 2