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

### Circuit Description

The Manifold Absolute Pressure (MAP) sensor is mounted to the rear of the intake manifold. The MAP sensor measures the pressure changes within the intake manifold which is an indication of the engine load. The MAP sensor has a 5.0 volt reference, a ground, and a signal circuit.

The MAP sensor contains a diaphragm which changes the resistance based on pressure. When the manifold pressure is low (high vacuum) the sensor output voltage is low. When the manifold pressure is high (low vacuum) the sensor output voltage is high.

The MAP sensor voltage (depending on altitude) can range from 1.0-1.5 volts at idle (high vacuum) to 4.0-4.9 volts at wide open throttle (low vacuum).

When the PCM senses a signal voltage lower than the normal operating range of the sensor, this DTC will set.

### Conditions for Running the DTC

• | No TP sensor DTCs set.

• | The engine is running.

• | The TP angle is no more than 20% when the engine speed is greater than 1200 RPM.

| OR

• | The TP angle is no more than 0% when the engine speed is no more than 1200 RPM.

### Conditions for Setting the DTC

• | The MAP sensor voltage is less than 0.10 volts.

• | All conditions met for greater than 2 seconds.

### Action Taken When the DTC Sets

• | The PCM illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.

• | The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the PCM stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the PCM records the operating conditions at the time of the failure. The PCM writes the conditions to the Freeze Frame and updates the Failure Records.

### Conditions for Clearing the MIL/DTC

• | The PCM turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.

• | A last test failed, or current DTC, clears when the diagnostic runs and does not fail.

• | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.

• | Use a scan tool in order to clear the MIL and the DTC.

### Diagnostic Aids:

Important:

• | Remove any debris from the PCM connector surfaces before servicing the PCM. Inspect the PCM connector gaskets when diagnosing/replacing the PCM. Ensure that the gaskets are installed correctly. The gaskets prevent water intrusion into the PCM.

• | For any test that requires probing the PCM or component harness connectors, use the Connector Test Adapter Kit J 35616 . Using this kit prevents damage to the harness connector terminals. Refer to Using Connector Test Adapters in Wiring Systems.

• | The following may cause an intermittent:

- | Mis-routed harness

- | Rubbed through wire insulation

- | Broken wire inside the insulation

• | The PCM 5.0 volt reference circuits are internally connected within the PCM. If all the MAP sensor circuits are OK, inspect the following component/circuits for malfunctions:

- | A/C Refrigerant Pressure sensor

- | EGR Valve

• | For an intermittent, refer to Symptoms .

### Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. If DTC P1635 sets at the same time, this indicates that the 5.0 volt reference circuit is either shorted to a ground or shorted to a voltage. The 5.0 volt reference circuit is internally connected within the PCM. The A/C Refrigerant Pressure sensor or the EGR valve may be causing this DTC to set. Refer to DTC P1635 for further diagnosis.

1. This step determines if the malfunction is present.

2. Using the Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame and/or Failure Records data can help determine how many miles since the DTC set. The Fail Counter and Pass Counter can also help determine how many ignition cycles the diagnostic reported a pass and/or a fail. Operate the vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature etc.) that you observed. This will isolate when the DTC failed.

3. If the scan tool displays 5.0 volts, the MAP sensor signal, 5.0 volt reference circuit, and the PCM are OK. For any test that requires probing the PCM or component harness connectors, use the Connector Test Adapter Kit J 35616 . Using this kit prevents any damage to the harness connector terminals.

4. If the scan tool displays 5.0 volts, the MAP sensor signal circuit and the PCM are OK. For any test that requires probing the PCM or component harness connectors, use the Connector Test Adapter Kit J 35616 . Using this kit prevents any damage to the harness connector terminals.

5. Disconnecting the PCM allows using the DMM J 39200 in order to test the continuity of the circuits. This aids in locating an open or a shorted circuit.

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. Install a scan tool.
2. Idle the engine.
3. Monitor the Diagnostic Trouble Code (DTC) Information using the scan tool.

Did DTC P1635 fail this ignition cycle?

--

Go to DTC P1635 5 Volt Reference 1 Circuit

Go to Step 3

3 | Monitor the MAP sensor voltage on Engine 1 Data List on the scan tool. Is the MAP sensor voltage below the specified value? | 0.10V | Go to Step 5 | Go to Step 4
4 |

1. Turn ON the ignition leaving the engine OFF.
2. Review the Freeze Frame and/or Failure Records data for this DTC and observe the parameters.
3. Turn OFF the ignition for 15 seconds.
4. Start the engine.
5. Operate the vehicle within the conditions required for this diagnostic to run, and as close to the conditions recorded in the Freeze Frame/Failure Records as possible. Special operating conditions that you need to meet before the PCM will run this diagnostic, where applicable, are listed in Conditions for Running the DTC.
6. Select the Diagnostic Trouble Code (DTC) option, the Specific DTC option, then enter the DTC number using the scan tool.

Does the scan tool indicate that this diagnostic failed this ignition?

--

Go to Step 5

Go to Diagnostic Aids

5 |

1. Disconnect the MAP sensor electrical connector.
2. Jumper the 5.0 volt reference circuit and the MAP sensor signal circuit together at the MAP sensor harness connector.
3. Observe the MAP sensor voltage display on the scan tool.

Is the MAP sensor voltage near the specified value?

5.0V

Go to Step 11

Go to Step 6

6 |

1. Connect the test lamp J 35616-200 between B+ and the MAP sensor signal circuit at the MAP sensor harness connector.
2. Observe the MAP sensor voltage display on the scan tool.

Is the MAP sensor voltage near the specified value?

5.0V

Go to Step 7

Go to Step 9

7 |

1. Turn OFF the ignition.
2. Disconnect the PCM connector C2 located on the same side as the manufacturer's logo. Refer to Powertrain Control Module Replacement/Programming .
3. Test the 5.0 volt reference circuit for an open or short to a ground.
4. If you find the 5.0 volt reference circuit is open or shorted to a ground, repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 8

8 |

1. Inspect the 5.0 volt reference circuit for a poor connection at the PCM. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.
2. If you find a poor connection repair the condition as necessary. Refer to Repairing Connector Terminals in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 12

9 |

1. Turn OFF the ignition.
2. Disconnect the PCM connector C2 located on the same side as the manufacturer's logo. Refer to Powertrain Control Module Replacement/Programming .
3. Test the MAP sensor signal circuit for the following:

• | Open circuit

• | Short to a ground

• | Short to sensor ground circuit

4. If you find the MAP sensor signal circuit is open or shorted to a ground, repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 10

10 |

1. Inspect the MAP sensor signal circuit for a poor connection at the PCM. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.
2. If you find a poor connection repair the condition as necessary. Refer to Repairing Connector Terminals in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 13

Go to Step 12

11 | Replace the MAP sensor. Refer to Manifold Absolute Pressure Sensor Replacement . Is the action complete? | -- | Go to Step 13 | --
12 | Important:: Program the replacement PCM. Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Is the action complete? | -- | Go to Step 13 | --
13 |

1. Select the Diagnostic Trouble Code (DTC) option and the Clear DTC Information option using the scan tool.
2. Idle the engine at the normal operating temperature.
3. Select the Diagnostic Trouble Code (DTC) option and the Specific DTC option, then enter the DTC number using the scan tool.
4. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text, if applicable.

Does the scan tool indicate that this test ran and passed?

--

Go to Step 14

Go to Step 2

14 | Select the Capture Info option and the Review Info option using the scan tool. Does the scan tool display any DTCs that you have not diagnosed? | -- | Go to the applicable DTC table | System OK