P1408

DTC P1408 MANIFOLD DIFFERENTIAL PRESSURE SENSOR CIRCUIT MALFUNCTION





WIRING DIAGRAM

CIRCUIT DESCRIPTION
This sensor senses pressure change in the intake manifold and converts it into voltage change. It consists of a semiconductor type pressure converting element which converts a pressure change into an electrical change and an electronic circuit which amplifies and corrects the electric change.
The ECM sends a 5-volt reference voltage to the pressure sensor. As the manifold pressure changes, the electrical resistance of the sensor also changes.
By monitoring the sensor output voltage, ECM knows the manifold pressure change when EGR valve is operated and judges the EGR flow to be faulty when this pressure change is excessively large or small.





DETECTING CONDITION

DTC CONFIRMATION PROCEDURE

WARNING:
- When performing a road test, select a p!ace where there is no traffic or possibility of a traffic accident and be very careful during testing to avoid occurrence of an accident.
- Road test should be carried out with 2 persons, a driver and a tester, on a level road.

NOTE: Check to make sure that following conditions are satisfied when using this DTC CONFIRMATION PROCEDURE.
- Intake air temp.: -10°C (14°F) or higher.
- Atmospheric pressure (Altitude) : 540 mmHg, 72 kPa or more (2790 m, 9150 ft or less).

1) Connect scan tool to DLC with ignition switch OFF.
2) Turn ON ignition switch and clear DTC, pending DTC and freeze frame data by using scan tool.
3) Start engine and warm up it completely.
4) Increase vehicle speed to 56km/h (35mph) or more.
5) Keep driving above vehicle speed for 30 sec.
6) Release accelerator pedal and stop vehicle.
7) Run engine at idle speed for 10 sec.
8) Check pending DTC and DTC by using scan tool.





TROUBLESHOOTING





TROUBLESHOOTING (SIGNAL VOLTAGE LOW)








Manifold Differential Pressure Sensor Check
1) Disconnect manifold differential pressure sensor vacuum hose from filter.
2) Disconnect manifold differential pressure sensor coupler.
3) Remove manifold differential pressure sensor.
4) Arrange 3 new 1 .5V batteries in series and connect its positive terminal to "Vin" terminal of coupler and negative terminal to "Ground" terminal. Then check voltage between "Vout" and "Ground".
Also, check if voltage reduces when vacuum is slowly applied up to 400 mmHg by using vacuum pump.

CAUTION: As connection to wrong terminal will cause damage to manifold differential pressure sensor, make absolutely sure to connect properly as shown in left figure.

If check result is not satisfactory, replace manifold differential pressure sensor.
5) Install manifold differential pressure sensor and connect vacuum hose securely.
6) Connect manifold differential pressure sensor coupler securely.