For 1990-2009 cars
Engine Controls Components
Cell 23: Engine Data Sensors
OBD II Symbol Description Notice
Powertrain Control Module Connector End Views With EGR
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

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

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

1. The Powertrain OBD System check prompts you to complete some of the basic checks and to store the Freeze Frame and Failure records data on the scan tool if applicable. This creates an electronic copy of the data captured when the malfunction occurred. The scan tool stores this data for later reference.

2. This diagnostic table should not be used if any DTCs are set. You need to diagnosis any DTCs that is set first.

3. 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 the voltage should be instantaneous. A slow voltage change indicates a malfunctioning sensor.

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

5. Important: Make sure that the electrical connector remains securely fastened.

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

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

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check
2 |

1. Turn ON the ignition switch leaving the engine OFF.
2. Install a scan tool.
3. Check for any DTCs.

Were any DTCs set?

--

Go to DTC Diagnostic Table first

Go to Step 3

3 | Compare the BARO reading with the reading of a known good vehicle. Are the BARO readings between the 2 vehicles within the specified value of each other ? | 3 kPa | Go to Step 4 | Go to Step 7
4 |

1. Disconnect and plug the vacuum source to the MAP sensor.
2. Connect a hand vacuum pump to the MAP sensor.
3. Observe the MAP sensor voltage on the scan tool.
4. Apply the first 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?

34 kPa (10 in of Hg) 1.5 V

Go to Step 6

Go to Step 7

5 |

1. Turn OFF the ignition switch.
2. Replace the MAP sensor.

Is the action complete?

--

Go to Step 9

--

6 | Check the MAP sensor vacuum source for the following conditions:

• | Leakage

• | Restriction

• | Vacuum source supplies the MAP sensor only

Was a repair necessary?

--

Go to Step 8

Go to Step 9

7 |

1. Turn OFF the ignition switch.
2. Check the MAP sensor electrical connector terminals for the following conditions:

• | Poor electrical terminal connections

• | Poor electrical terminal tension

3. Repair the terminals as necessary.

Was a repair necessary?

--

Go to Step 9

Go to Step 5

8 |

1. Turn OFF the ignition switch.
2. Repair any leakage or restriction in the MAP sensor vacuum source.

Is the action complete?

--

Go to Step 9

9 |

1. Start the engine.
2. Operate the vehicle within the conditions under which the original symptom was observed.

Does the system now operate properly?

--

System OK

Go to Step 2