Manifold Pressure/Vacuum Sensor: Testing and Inspection

Manifold Absolute Pressure Sensor and Intake Air Temperature Sensor, Checking

The following procedure is used to diagnose the Manifold Absolute Pressure (MAP) Sensor (G71) and Intake Air Temperature (IAT) Sensor (G42) which is controlled by Engine Control Module (J623).

• The Intake Air Temperature (IAT) Sensor (G42) is part of the Manifold Absolute Pressure (MAP) Sensor (G71) and cannot be replaced separately

• Use only gold-plated terminals when servicing terminals in harness connector of Manifold Absolute Pressure (MAP) Sensor (G71)/Intake Air Temperature (IAT) Sensor (G42).

Special tools, testers and auxiliary items required

• multimeter.

• Wiring diagram.

Test requirements

• The Engine Control Module (ECM) (J623) fuse OK.

• Battery voltage at least 12.5 volts.

• All electrical consumers such as, lights and rear window defroster, switched off.

• Vehicles with automatic transmission, shift selector lever into position "P" or "N".

• A/C switched off.

• Ground (GND) connections between engine/transmission/chassis OK.

• Coolant Temperature at least 80° C.

• Ignition switched off.

Test procedure

- Perform a preliminary check to verify the customers complaint. Refer to => [ Preliminary Check ] Preliminary Check.

Start diagnosis

- Connect the scan tool.

- Start engine and let it run at idle.

- Using the scan tool, Check the temperature of the Manifold Absolute Pressure (MAP) Sensor (G71) and Intake Air Temperature (IAT) Sensor (G42) at idle:





- End diagnosis and switch ignition off.

If the specified value was obtained, but the DTC memory has a DTC indicating a Manifold Absolute Pressure (MAP) Sensor (G71)/Intake Air Temperature (IAT) Sensor (G42) fault:

- Check the voltage supply of the Manifold Absolute Pressure (MAP) Sensor (G71)/Intake Air Temperature (IAT) Sensor (G42).

If specified value was not obtained:

- Check the wiring of the Manifold Absolute Pressure (MAP) Sensor (G71)/Intake Air Temperature (IAT) Sensor (G42).

Checking voltage supply

- Remove the engine cover - arrows -. Refer to appropriate service information.





- Disconnect the Manifold Absolute Pressure (MAP) Sensor (G71) and Intake Air Temperature (IAT) Sensor (G42) electrical harness connector - 1 -.





- Crank the engine.

- Using a multimeter, check the Manifold Absolute Pressure (MAP) Sensor (G71)/Intake Air Temperature (IAT) Sensor (G42) electrical harness connector terminal 3 to engine Ground (GND) for voltage.





Specified value: approx 5 V.

- Switch the ignition off.

If specified value was not obtained:

- Check the electrical harness connector for damage, corrosion, loose or broken terminals.

If no malfunction is detected in the wiring and the voltage supply was OK:

Checking electrical circuit

If the manufacturers test box is being used, perform the following step.

- Install the test box.

If the manufacturers test box is not being used, perform the following step.

- Remove the Engine Control Module (J623). Refer to appropriate service information.

- Using a multimeter, check the Manifold Absolute Pressure (MAP) Sensor (G71)/Intake Air Temperature (IAT) Sensor (G42) electrical harness connector terminals to the Engine Control Module (J623) electrical harness connector T60 terminals for resistance.









Specified value: 1.5 ohms max.

If any of the specified values were not obtained:

- Check the wiring for an open circuit, a short circuit to each other, Battery (+), or Ground (GND).

- Check the electrical harness connector for damage, corrosion, loose or broken terminals.

- If necessary, repair the faulty wiring connection.

If no malfunction is detected in the wiring and if the voltage supply was OK:

- Replace the Manifold Absolute Pressure (MAP) Sensor (G71) /Intake Air Temperature (IAT) Sensor (G42).

- Erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Modes 01 - 09.

- Perform a road test to verify repair.

If the DTC does not return:

Repair complete, Generate readiness code. Refer to => [ Readiness Code ] Monitors, Trips, Drive Cycles and Readiness Codes.

- End diagnosis.

If the DTC returns and no malfunction is found in the wiring and voltage supply was OK:

- Replace the Engine Control Module (J623).

Assembly is performed in the reverse order of the removal, note the following:

Final procedures

After repair work, the following work steps must be performed in the following sequence:

1. Check the DTC memory. Refer to => [ Diagnostic Mode 03 - Read DTC Memory ] Diagnostic Modes 01 - 09.

2. If necessary, erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Modes 01 - 09.

3. If the DTC memory was erased, generate readiness code. Refer to => [ Readiness Code ] Monitors, Trips, Drive Cycles and Readiness Codes.