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-.

Special tools and workshop equipment required 

• multimeter.
• Wiring diagram.

Test conditions 

• 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 requirements 

-- Perform a preliminary check to verify the customers complaint. Refer to 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:

Diagnostic text		Specified value
Intake air temperature sensor
Engine running at idle		approx. ambient temperature

-- 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-, refer to "Checking voltage supply  " (See Fig 1).

If specified value was not obtained:

-- Check the wiring of the Manifold Absolute Pressure (MAP) Sensor -G71- /Intake Air Temperature (IAT) Sensor -G42-, refer to " Checking electrical circuit  " (See Fig 4).

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.

Manifold Absolute Pressure (MAP) Sensor -G71- /Intake Air Temperature (IAT) Sensor -G42- electrical harness connector terminals	Engine Control Module -J623- electrical connector T60 terminals or test box socket
1	50
2	41
3	35
4	37

Specified value: 1.5 Ω 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 .

-- Perform a road test to verify repair.

If the DTC does not return:

Repair complete, Generate readiness code. Refer to READINESS CODE .

-- 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-. Refer to the service information for removal and installation procedures.

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 .
2. If necessary, erase the DTC memory. Refer to DIAGNOSTIC MODE 04 - ERASE DTC MEMORY .
3. If the DTC memory was erased, generate readiness code. Refer to READINESS CODE .