Nissan Maxima QX

since 1993 release

Repair and operation of the car

Check of a state and replacement of the sensor of absolute pressure in the pipeline (MAR)

On models since 1996 the sensor of absolute pressure in the pipeline complete with the MAR electromagnetic valve is used by the issue for tracking depression depth in the inlet pipeline. Change of this parameter of rather barometric pressure is result of changes of the current load of the engine and its turns. RSM uses the signals arriving from the MAR sensor in the diagnostic purposes. At delivery by the module of management of tension on the MAR electromagnetic valve the last provides development of the vacuum signal switching the MAR sensor to measurement of barometric pressure. In the absence of tension on the valve the MAR sensor makes reading of depth of depression in the pipeline which any change will be transformed to the alarm tension right there transferred to RSM. Amplitude of the signal developed by the sensor can change in the range from 0.5 V at completely closed butterfly valve, to 5.0 B at completely open (low depth of depression). Also certain dependence of amplitude of the signal from the barometric pressure determined by height of position of the car above sea level developed by the sensor takes place. The sensor and the MAR electromagnetic valve are installed on back (from transmission) an end face of the left (lobby) head of cylinders. RSM distinguishes several types of violations of functioning of the sensor, to each of which OBD assigns an individual code for malfunction.

CHECK

Implementation of the procedure described below can lead to entering in memory of OBD of malfunction which will be highlighted by a control lamp "Check the engine". Upon completion of check and the corresponding recovery repair do not forget to clear memory of system (see the Section System of Onboard Diagnostics (OBD) - the principle of functioning and codes of malfunctions).

MAR sensor

PERFORMANCE ORDER

1. Disconnect a vacuum hose from the MAR sensor and connect to the last the vacuum gage. Start the engine on single turns, - about 5 seconds later the measuring instrument has to register depression, otherwise check the vacuum hose connecting the sensor to the electromagnetic valve on existence of cracks and signs of violation of passability. If a hose as it should be, it is necessary to make check of a condition of the electromagnetic valve. In the presence of depression you pass to check of a condition actually of the MAR sensor.
2. Disconnect an electrical wiring from the MAR sensor. Connect the voltmeter to plugs red (+) and a black wire on the socket. At the included ignition (the engine do not start) the measuring instrument has to issue the indication in 5.0 B, otherwise check a condition of a chain on the site between the socket and RSM. If an electrical wiring and contact connections as it should be, the car has to be driven away on car repair shop for performing diagnostics of a condition of the module of management and performance of the corresponding recovery repair.
3. Switch off ignition and connect an electrical wiring to the sensor. Connect the positive probe of the fan to the plug of a white wire from a reverse side of the socket (for more details see the Head Onboard electric equipment), ground the negative probe on weight. Include ignition (the engine do not start), - tension in the range from 3.2 to 4.8 V has to take place.
4. Disconnect a vacuum hose from the sensor and instead of it connect the manual vacuum pump. Create depression about 203 mm Hg in depth on the sensor. Amplitude of the alarm tension developed by the sensor has to fall to value 1.0 ÷ 1.4 B, otherwise replace assembly.

Electromagnetic valve

PERFORMANCE ORDER

1. Disconnect a hose of a source of depression of the inlet pipeline from the MAR electromagnetic valve. Connect the vacuum gage to a hose. Start the engine on single turns, - the measuring instrument has to register depression, otherwise check a condition of a hose for existence of cracks and signs of violation of passability. If a hose as it should be, you pass directly to check of a condition of the valve.
2. Disconnect an electrical wiring from the MAR electromagnetic valve and make sure available battery tension between two plugs of the socket at the included ignition (a distance do not start). If tension is absent, address schemes of electric connections (see the Head Onboard electric equipment) and check the corresponding chain for existence of signs of breaks on the site between the assembly block of safety locks and the socket of the valve (first of all, naturally, it is necessary to check a condition of safety locks).

3. If tension of the battery takes place, remove the electromagnetic valve and you pass to diagnostics of its state out of the car. By means of couple of wires crossing points equipped with safety locks connect the valve to the 12-voltny power supply. At the time of giving of tension the valve has to publish clearly distinguishable click which is followed by opening of the air channel between unions A and B. In the absence of tension the channel between unions A and C has to open. The faulty valve is subject to replacement.

And — To the MAR sensor
In — To an inlet air duct
With — To a source of depression of the inlet pipeline

REPLACEMENT

PERFORMANCE ORDER

1. Disconnect a negative wire from the battery.

If the stereosystem established on the car is equipped with a security code before disconnecting the battery make sure that you have the correct combination for introduction of the equipment to action!

2. Disconnect an electrical wiring from the sensor and/or the MAR electromagnetic valve.
3. Turn out screws of fastening of the sensor and/or the MAR electromagnetic valve. Disconnect a vacuum hose(s) and remove the corresponding assembly.
4. Installation is made upside-down.