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CVT gearboxes NISSAN NCVT, CVT, Hyper CVT M6

CVT gearboxes NISSAN NCVT, CVT, Hyper CVT M6 1
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CVT gearboxes NISSAN NCVT, CVT, Hyper CVT M6

NISSAN was one of the first to put variable-speed (continuously variable) transmissions on its cars. Let’s consider CVT models and binding to a model range of cars.

1. NCVT – this transmission is placed on a small car with a volume of up to 1500 cm3

It is completely hydraulic to control, in other words, it has a similar block of hydraulic valves, as in a conventional automatic transmission, only the resulting pulley is moving. GT – powder type (electrical coupling). The main failure is when there is no increase – reduction in the gear ratio, such as emergency mode (2nd gear). There are several trim screws on the hydraulic unit that change its operation. Obviously, to set up, there should be a special stand for this unit, on which you can configure its operation. I have not met the owners who were able to repair such an NCVT, they all set themselves a normal automatic transmission .

2. CVT ( REOFO 6 A ) – fully electronically controlled transmission. Installed on models with 1.8 – 2.0 liter petrol engines (SR 18 ..)

The main control element is made in the form of a stepper servo motor. On commands from the ECT, it controls, through the profile lever, a high-pressure valve that supplies fluid to the compression circuit of the drive pulley. The driven pulley is preloaded by a coil spring and is unclenched by the wedging of the steel belt (chain). In addition, the CVT has a pressure control valve (PWM) like a conventional automatic transmission (ballast on the CVT housing above the differential), a GT lock-off valve, a temperature sensor, and a pressure sensor. The rotation speed of the driving and driven pulleys is measured by external Hall effect sensors. They are interchangeable except for the mounting foot – another U-turn, electrically compatible. The main failure is the failure of the stepper servo motor (step motor). To replace it, it is enough to drain the oil, remove the pan, remove the filter by carefully separating the wiring harness. The step motor itself is fastened with two bolts, it will be easier to pull out and insert, not forgetting the curly lever, if you manually pull the actuator rod out of the motor.

After removing the filter – pay attention to the conical surfaces of the pulleys – they are yellow. The presence of scratches indicates slippage of the chain, ideally they should be mirrored. Ask the owner what speed he was driving. Typically, a car with such a CVT greater than 120 km / h does not accelerate, or accelerates, but very slowly.

Diagnostics – the car does not drive, the CVT lamp flashes. Ideally, a scanner. But if he is not, or he does not read such a transmission, then we remove the connector on the case immediately after the radiator. 2 rows of 5 contacts. We check the resistance of the phase windings st ep motor. Relative to the midpoint – 15 ohms, only 4 windings. As a rule, a break in one of the phase windings. Such a resistance had a step motor of an early sample, later models have about 20 ohms. Such do not fail.

The transmission (mechanical part) is completely similar to the previous one. The difference is only in the gear selector – a manual switching mode is introduced and another electronic unit is added. A tribute to fashion gave its result – virtual cars constantly drove on such machines, the boxes do not live on them for a long time. For example, a NISSAN CAMINO with an SR 20 DE VVL engine with a system for changing the camshaft phases and valve lift heights is about 190 hp, the machine is very dynamic in combination with a variator transmitting maximum torque from the engine in the entire range. Mechanically and electrically, these automatic transmissions are interchangeable.

There is another CVT EXTROID, which is installed on the CEDRIC – GLORIA with a 280 hp engine, a torus system is used instead of a V-belt, but you did not have to deal with such a CVT.

1. When replacing the regulator, change the oil filter (number 31728) – this will extend the life of the box.
2. When removing the pallet and replacing the step motor (number 31947 – the cost is about 3200 rubles), 5 liters of oil will be required. Only original NS1 can be poured. Gulf of another leads to the failure of the CVT in just a couple of laps. I saw examples. A warning of damage is affixed to the oil level dipstick plug.

3. Due to the intensive operation of the transmission in the urban mode, it is recommended to change the oil twice as often as prescribed for the domestic market, since the main wear of the chain is due to dirty oil that has lost its properties.

4. You should be careful when buying a minivan (for example, NISSAN SERENA) with such a transmission, because even on the BLUEBIRD with mileage the chain skids due to wear and tear, and the shaft bearings simply fall apart on a seven-seater minivan. Unfortunately, NISSAN puts a manual transmission on the diesel version of the YD 25 DDTi, which has a lot of complaints, and the proven SR 20 DE _ only CVT .

5. In my opinion, repair (except electronic malfunctions) of such a box is not justified, since the cost of the chain is quite high, and the condition of the wedge pulleys leaves much to be desired when the chain is completely worn out. Before making a decision – it is imperative to assess the condition of pulley wear.

Explanations for the diagram – compiled from a faulty CVT

The connector on the box, top view.

CVT gearboxes NISSAN NCVT, CVT, Hyper CVT M6 2

1. Step motor windings – each phase (for example, pin 2 – housing) is about 15 Ohms in the old regulator. In newer ones, the resistance is increased to 20 Ohms..
Conclusions 2-3 and 4-5 on 30 Ohms or 40 .
2. The temperature sensor (terminals 6-7) is similar in conventional automatic transmissions, the resistance is about 2.5 kOhm, the cold voltage with the connected connector is 1.5 volts, hot – about 0.5 V
3. Conclusion 8 – HPSV – linear pressure control valve, similar to a conventional automatic transmission, when the ignition is turned on and the gas pedal is gently pressed in the CVT region, it should crack, which indicates the functioning of the valve itself and a dropping resistor (dropping resistor – 12 Ohm resistance ), Valve resistance of about 3 ohms.
4. Conclusion 9 – TCLS – HT blocking valve – 15 Ohm, blocks the GT to reduce losses and increase efficiency.
5. Conclusion 1 – CVT pressure sensor , most likely electronic, VCC power supply – 5 V at the output xx mode, warmed up – about 1 V, stall test mode – about 4 V

Known DTCs

P 1791 – oil pressure sensor

P 1777 – electrical failure step motor _ open winding

P 1778 – mechanical failure step motor _ windings whole, wedged or not adjustment

P 0710 – temperature sensor

P 0745 – HPS pressure control solenoid

P0740 – GT blocking solenoid

Note: photo of pressure regulator

GADZHIEV A.O.
© Legion Avtodata

Gadzhiev Arid Omarovich

Moscow, st. Ermakova Grove 7A, territory 14 TMP

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