Automatic Transmission: Overview Nissan 370Z I

DESCRIPTION

There are many operating conditions that may cause a malfunction of the transmission parts. By understanding those conditions properly, a quick and exact diagnosis can be achieved.

In general, customers have their own criteria for a problem. Therefore, it is important to understand the symptom and status well enough by asking the customer about the concerns carefully. In order to systemize all the information for the diagnosis, prepare the question sheet referring to the question points.

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SYSTEM DESCRIPTION

1. The A/T senses vehicle operating conditions through various sensors or signals. It always controls the optimum shift position and reduces shifting and lock-up shocks.
2. Receive input signals transmitted from various switches and sensors.
3. Determine required line pressure, shifting point, lock-up operation, etc.
4. Transmit required output signals to the respective solenoids.

Scheme 4

Note. The following components are included in control valve & TCM. TCM Input speed sensor 1, 2 A/T fluid temperature sensor Transmission range switch Direct clutch solenoid valve High and low reverse clutch solenoid valve Input clutch solenoid valve Front brake solenoid valve Low brake solenoid valve Anti-interlock solenoid valve 2346 brake solenoid valve Line pressure solenoid valve Torque converter clutch solenoid valve

Component Description

COMPONENT DESCRIPTION

Scheme 5

1. When an engine and A/T integrated control signal (engine torque) equivalent to the engine drive force is transmitted from the ECM to the TCM, the TCM controls the line pressure solenoid valve. This line pressure solenoid controls the pressure regulator valve as the signal pressure and adjusts the pressure of the operating oil discharged from the oil pump to the line pressure most appropriate to the driving state.
2. The TCM has stored in memory a number of patterns for the optimum line pressure characteristic for the driving state.
3. In order to obtain the most appropriate line pressure characteristic to meet the current driving state, the TCM controls the line pressure solenoid current value and thus controls the line pressure.

Normal Control

Each clutch is adjusted to the necessary pressure to match the engine drive force.

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Back-up Control (Engine Brake)

When the select operation is performed during driving and the A/T is shifted down, the line pressure is set according to the vehicle speed.

Scheme 7

During Shift Change

The necessary and adequate line pressure for shift change is set. For this reason, line pressure pattern setting corresponds to engine torque and gearshift selection. Also, line pressure characteristic corresponds to engine speed, during engine brake operation.

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At Low Fluid Temperature

When the A/T fluid temperature drops below the prescribed temperature, in order to speed up the action of each friction element, the line pressure is set higher than the normal line pressure characteristic.

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Note. The following components are included in control valve & TCM. TCM Input speed sensor 1, 2 A/T fluid temperature sensor Transmission range switch Direct clutch solenoid valve High and low reverse clutch solenoid valve Input clutch solenoid valve Front brake solenoid valve Low brake solenoid valve Anti-interlock solenoid valve 2346 brake solenoid valve Line pressure solenoid valve Torque converter clutch solenoid valve

COMPONENT DESCRIPTION

Scheme 11

The clutch pressure control solenoid is controlled by the signals from the switches and sensors. Thus, the clutch pressure is adjusted to be appropriate to the engine load state and vehicle driving state. It becomes possible to finely control the clutch hydraulic pressure with high precision and a smoother shift change characteristic is attained.

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Shift Change

The clutch is controlled with the optimum timing and oil pressure by the engine speed, engine torque information, etc.

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*1: Full phase real-time feedback control monitors movement of gear ratio at gear change, and controls oil pressure in real-time to achieve the best gear ratio.

Blipping Control

This system makes transmission clutch engage readily by controlling (synchronizing) engine revolution according to the (calculation of) engine revolution after shifting down.

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1. "BLIPPING CONTROL" functions. When downshifting by accelerator pedal depression. When downshifting by the manual mode.
2. TCM selects "BLIPPING CONTROL" or "NORMAL SHIFT CONTROL" according to the gear position, the selector lever position, the engine torque and the speed when accelerating by pedal depression.
3. Engine speed control demand signal is transmitted from TCM to ECM under "BLIPPING CONTROL".
4. ECM synchronizes the engine speed according to the engine speed control demand signal.

Scheme 17

Note. The following components are included in control valve & TCM. TCM Input speed sensor 1, 2 A/T fluid temperature sensor Transmission range switch Direct clutch solenoid valve High and low reverse clutch solenoid valve Input clutch solenoid valve Front brake solenoid valve Low brake solenoid valve Anti-interlock solenoid valve 2346 brake solenoid valve Line pressure solenoid valve Torque converter clutch solenoid valve

COMPONENT DESCRIPTION

Scheme 18

SHIFT PATTERN : System Description

INPUT/OUTPUT SIGNAL CHART

INPUT/OUTPUT SIGNAL DESCRIPTION

SYSTEM DESCRIPTION

It automatically selects the shift pattern (such as road environment and driving style) suitable for the various situations so as to allow the vehicle to be driven efficiently and smoothly.

TCM judges up/down slope according to engine torque data transmitted from the ECM and vehicle speed. Fixing at 4GR, 5GR or 6GR on an up-slope prevents shift hunting and controls the vehicle to gain optimum driving force. On a down-slope, automatic shift-down to 4GR, 5GR or 6GR controls to gain optimum engine brake.

Scheme 19

Note. The following components are included in control valve & TCM. TCM Input speed sensor 1, 2 A/T fluid temperature sensor Transmission range switch Direct clutch solenoid valve High and low reverse clutch solenoid valve Input clutch solenoid valve Front brake solenoid valve Low brake solenoid valve Anti-interlock solenoid valve 2346 brake solenoid valve Line pressure solenoid valve Torque converter clutch solenoid valve

Scheme 20

Note. The following components are included in control valve with TCM. TCM Input speed sensor 1, 2 Output speed sensor A/T fluid temperature sensor Transmission range switch Direct clutch solenoid valve High and low reverse clutch solenoid valve Input clutch solenoid valve Front brake solenoid valve Low brake solenoid valve Anti-interlock solenoid valve 2346 brake solenoid valve Line pressure solenoid valve Torque converter clutch solenoid valve *: Control valve with TCM is included in A/T assembly.

SHIFT PATTERN : Component Description

COMPONENT DESCRIPTION

Scheme 21

MANUAL MODE : System Description

INPUT/OUTPUT SIGNAL CHART

INPUT/OUTPUT SIGNAL DESCRIPTION

SYSTEM DESCRIPTION

Manual Mode

1. The TCM receives the manual mode signal, non-manual mode signal, manual mode shift up signal, manual mode shift down signal, paddle shifter shift up signal and paddle shifter shift down signal from combination meter via CAN communication line. The TCM shifts shift pattern control to the manual mode based on these signals, and then shifts the A/T by operating each solenoid valve according to the shift operation of the driver.
2. The TCM prohibits the manual mode while being in fail-safe mode due to an A/T malfunction, etc. Refer to " «FAIL-SAFE»(ref-402639-S27665455412011053100000) ".
3. The TCM transmits the manual mode shift refusal signal to the combination meter if the TCM refuses the transmission from the driving status of vehicle when the selector lever or paddle shifter shifts to "UP (+ side)" or "DOWN (- side)" side. The combination meter blinks shift indicator on the combination meter and sounds the buzzer to indicate the driver that the shifting is not performed when receiving this signal. However, the TCM does not transmit the manual mode shift refusal signal in the conditions as per the following. When the selector lever or the paddle shifter shifts to "DOWN (- side)" side while driving in 1GR. When the selector lever or the paddle shifter shifts to "UP (+ side)" side while driving in 7GR.

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Note. The following components are included in control valve & TCM. TCM Input speed sensor 1, 2 A/T fluid temperature sensor Transmission range switch Direct clutch solenoid valve High and low reverse clutch solenoid valve Input clutch solenoid valve Front brake solenoid valve Low brake solenoid valve Anti-interlock solenoid valve 2346 brake solenoid valve Line pressure solenoid valve Torque converter clutch solenoid valve

MANUAL MODE : Component Description

COMPONENT DESCRIPTION

Scheme 23

The torque converter clutch piston in the torque converter is engaged to eliminate torque converter slip to increase power transmission efficiency.

The torque converter clutch control valve operation is controlled by the torque converter clutch solenoid valve, which is controlled by a signal from TCM, and the torque converter clutch control valve engages or releases the torque converter clutch piston.

Lock-up operation condition table

SYSTEM DESCRIPTION

Torque Converter Clutch Control Valve Control

Lock-up control system diagram

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Lock-up released

1. In the lock-up released state, the torque converter clutch control valve is set into the unlocked state by the torque converter clutch solenoid and the lock-up apply pressure is drained. in this way, the torque converter clutch piston is not coupled.

Lock-up Applied

1. In the lock-up applied state, the torque converter clutch control valve is set into the locked state by the torque converter clutch solenoid and lock-up apply pressure is generated. In this way, the torque converter clutch piston is pressed and coupled.

Smooth Lock-up Control

When shifting from the lock-up released state to the lock-up applied state, the current output to the torque converter clutch solenoid is controlled with the TCM. In this way, when shifting to the lock-up applied state, the torque converter clutch is temporarily set to the half-clutched state to reduce the shock.

Half-clutched State

1. The current output from the TCM to the torque converter clutch solenoid is varied to steadily increase the torque converter clutch solenoid pressure. In this way, the lock-up apply pressure gradually rises and while the torque converter clutch piston is put into half-clutched states, the torque converter clutch piston operating pressure is increased and the coupling is completed smoothly.

Slip Lock-up Control

1. In the slip region, the torque converter clutch solenoid current is controlled with the TCM to put it into the half-clutched state. This absorbs the engine torque fluctuation and lock-up operates from low speed. This raises the fuel efficiency for 2GR, 3GR, 4GR, 5GR, 6GR and 7GR.

Scheme 25

Note. The following components are included in control valve & TCM. TCM Input speed sensor 1, 2 A/T fluid temperature sensor Transmission range switch Direct clutch solenoid valve High and low reverse clutch solenoid valve Input clutch solenoid valve Front brake solenoid valve Low brake solenoid valve Anti-interlock solenoid valve 2346 brake solenoid valve Line pressure solenoid valve Torque converter clutch solenoid valve

COMPONENT DESCRIPTION

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With the use of 4 sets of planetary gears, A/T enables 7-speed transmission for forward and 1-speed transmission for backward, depending on the combination of 3 sets of multiple-disc clutches, 4 sets of multiple-disc brakes and 2 sets of one-way clutches.

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COMPONENT DESCRIPTION

1. Shift lock prevents an unintentional start of the vehicle that may be caused by an incorrect operation while selector lever is in the "P" position.
2. Selector lever can be shifted from the "P" position to another position when the following conditions are satisfied. Ignition switch ON Stop lamp switch is ON (brake pedal is depressed) Selector lever knob button is pressed

Scheme 29

SHIFT LOCK OPERATION

When brake pedal is not depressed and selector lever is in "P" position. (Unable to shift selector lever.) Without brake pedal depressed and with ignition switch ON, electromagnet (A) of slider (B) is not magnetized because of non electrical current. When selector lever knob button is pressed in this situation, detent pin (C) lowers. According to the movement of detent pin, plate (D) also lowers while pressing slider into shift lock unit. However, stopper (E) pressed by spring comes underneath plate. Plate cannot lower further when it contacts stopper, and detent pin cannot lower to the point that releases selector lever. Thus selector lever stays in the "P" position and selector lever is unable to shift.

Scheme 30

When brake pedal is depressed and selector lever is in "P" position. (Able to shift selector lever.)

With brake pedal depressed and with ignition switch ON, electromagnet (A) of slider (B) becomes magnetized because of live electricity. stopper (C) has an iron plate (D) to unify stopper with slider when electromagnet becomes magnetized. When selector lever knob button is pressed in this situation, detent pin (E) lowers. According to the movement of detent pin, plate (F) also lowers while pressing slider into shift lock unit. Because stopper is unified with slider, the slider unit moves into shift lock unit. Detent pin lowers to the point that releases selector lever from the "P" position and selector lever becomes able to shift.

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COMPONENT DESCRIPTION

Diagnosis Description

The A/T system has two self-diagnostic systems.

The first is the emission-related on board diagnostic system (OBD-II) performed by the TCM in combination with the ECM. A malfunction is indicated by the MIL (malfunction indicator lamp) and is stored as a DTC in the ECM memory and in the TCM memory.

The second is the TCM original self-diagnosis indicated by the TCM. A malfunction history is stored in the TCM memory. The detected items are overlapped with OBD-II self-diagnostic items. For details, refer to " DTC INDEX ".

The amount of data transmitted from each control unit is read.

CAN (Controller Area Network) is a serial communication line for real-time application. It is an on-vehicle multiplex communication line with high data communication speed and excellent malfunction detection ability. Many electronic control units are equipped onto a vehicle, and each control unit shares information and links with other control units during operation (not independently). In CAN communication, control units are connected with 2 communication lines (CAN-H line, CAN-L line) allowing a high rate of information transmission with less wiring. Each control unit transmits/receives data but selectively reads required data only.

The TCM prohibits cranking other than at "P" or "N" position.

The transmission range switch detects the selector lever position and transmits a signal to the TCM.

The A/T fluid temperature sensor detects the A/T fluid temperature and transmits a signal to the TCM.

The input speed sensor detects input shaft rpm (revolutions per minute). It is located on the input side of the A/T. Monitors revolution of sensor 1 and sensor 2 for non-standard conditions.

The output speed sensor detects the revolution of the parking gear and emits a pulse signal. The pulse signal is transmitted to the TCM which converts it into vehicle speed.

The engine speed signal is transmitted from the ECM to the TCM via CAN communication line.

This malfunction is detected when the A/T does not shift into 6GR position as instructed by TCM. This is not only caused by electrical malfunction (circuits open or shorted) but by mechanical malfunction such as control valve sticking, improper solenoid valve operation, etc.

1. The TCM detects a high-rpm state of the under drive sun gear.
2. The number of revolutions of the under drive sun gear is calculated with the input speed sensor 1 and 2.

This malfunction is detected when the A/T does not shift into 1GR position as instructed by TCM. This is not only caused by electrical malfunction (circuits open or shorted) but by mechanical malfunction such as control valve sticking, improper solenoid valve operation, etc.

This malfunction is detected when the A/T does not shift into 2GR position as instructed by TCM. This is not only caused by electrical malfunction (circuits open or shorted) but by mechanical malfunction such as control valve sticking, improper solenoid valve operation, etc.

This malfunction is detected when the A/T does not shift into 3GR position as instructed by TCM. This is not only caused by electrical malfunction (circuits open or shorted) but by mechanical malfunction such as control valve sticking, improper solenoid valve operation, etc.

This malfunction is detected when the A/T does not shift into 4GR position as instructed by TCM. This is not only caused by electrical malfunction (circuits open or shorted) but by mechanical malfunction such as control valve sticking, improper solenoid valve operation, etc.

This malfunction is detected when the A/T does not shift into 5GR position as instructed by TCM. This is not only caused by electrical malfunction (circuits open or shorted) but by mechanical malfunction such as control valve sticking, improper solenoid valve operation, etc.

1. The torque converter clutch solenoid valve is activated, with the gear in D2, D3, D4, D5, D6, D7, M2, M3, M4, M5, M6 and M7 by the TCM in response to signals transmitted from the output speed sensor and accelerator pedal position sensor. Torque converter clutch piston operation will then be controlled.
2. Lock-up operation, however, is prohibited when A/T fluid temperature is too low.
3. When the accelerator pedal is depressed (less than 1.0/8) in lock-up condition, the engine speed should not change abruptly. If there is a big jump in engine speed, there is no lock-up.

This malfunction is detected when the A/T does not lock-up. This is not only caused by electrical malfunction (circuits open or shorted) but also by mechanical malfunction such as control valve sticking, improper solenoid valve operation, etc.

The line pressure solenoid valve regulates the oil pump discharge pressure to suit the driving condition in response to a signal transmitted from the TCM.

1. Anti-interlock solenoid valve prevents the simultaneous activation of the input clutch and the low brake.
2. The anti-interlock solenoid valve is an ON/OFF type solenoid valve.

1. The Input clutch solenoid valve is controlled by the TCM in response to signals transmitted from the transmission range switch, output speed sensor and accelerator pedal position sensor. Gears will then be shifted to the optimum position.
2. The Input clutch solenoid valve controls the input clutch control valve in response to a signal transmitted from the TCM.

The TCM detects the malfunction of low brake solenoid valve. This is not only caused by electrical malfunction (circuits open or shorted) but also by mechanical malfunction such as control valve sticking, improper solenoid valve operation, etc.

1. The front brake solenoid valve is controlled by the TCM in response to signals transmitted from the transmission range switch, output speed sensor and accelerator pedal position sensor. Gears will then be shifted to the optimum position.
2. The front brake solenoid valve controls the front brake control valve in response to a signal transmitted from the TCM.

1. The accelerator pedal position sensor is installed on the upper end of the accelerator pedal assembly.
2. The accelerator pedal position sensor detects the accelerator position.
3. The accelerator pedal position sensor transform the accelerator pedal position into output voltage, and emit the voltage signal to the ECM.
4. The TCM receives accelerator pedal position signal from the ECM via CAN communication.

The vehicle speed signal is transmitted from combination meter to TCM via CAN communication line. The signal functions as an auxiliary device to the output speed sensor when it is malfunctioning. The TCM will then use the vehicle speed signal.

Fail-safe function to detect interlock conditions.

This malfunction is detected when the A/T does not shift into 7GR position as instructed by TCM. This is not only caused by electrical malfunction (circuits open or shorted) but by mechanical malfunction such as control valve sticking, improper solenoid valve operation, etc.

1. The manual mode switch [manual mode select switch and manual mode position select switch (shift-up/shiftdown)] is installed in the A/T shift selector assembly.
2. The manual mode select switch detects the position (the main shift gate side or manual shift gate side) of the selector lever and transmits a manual mode signal or a not manual mode signal to the combination meter Then, the TCM receives a manual mode signal or non-manual mode signal from the combination meter.
3. The manual mode position select switch (shift-up) detects that the selector lever is shifted to the shift-up side of the manual shift gate and transmits a manual mode shift up signal to the combination meter. Then, the TCM receives a manual mode shift up signal from the combination meter.
4. The manual mode position select switch (shift-down) detects that the selector lever is shifted to the shiftdown side of the manual shift gate and transmits a manual mode shift down signal to the combination meter. Then, the TCM receives a manual mode shift down signal from the combination meter.
5. The paddle shifter transmits shift up and shift down switch signals to the combination meter. Then TCM receives signals from the combination meter via CAN communication.

1. The high and low reverse clutch solenoid valve is controlled by the TCM in response to signals transmitted from the transmission range switch, output speed sensor and accelerator pedal position sensor. Gears will then be shifted to the optimum position.
2. The high and low reverse clutch solenoid valve controls the high and low reverse clutch control valve in response to a signal transmitted from the TCM.

1. The low brake solenoid valve is controlled by the TCM in response to signals transmitted from the transmission range switch, output speed sensor and accelerator pedal position sensor. Gears will then be shifted to the optimum position.
2. The low brake solenoid valve controls the low brake control valve in response to a signal transmitted from the TCM.

1. The 2346 brake solenoid valve is controlled by the TCM in response to signals transmitted from the transmission range switch, output speed sensor and accelerator pedal position sensor. Gears will then be shifted to the optimum position.
2. The 2346 brake solenoid valve controls the 2346 brake control valve in response to a signal transmitted from the TCM.

1. The direct clutch solenoid valve is controlled by the TCM in response to signals transmitted from the transmission range switch, output speed sensor and accelerator pedal position sensor. Gears will then be shifted to the optimum position.
2. The direct clutch solenoid valve controls the direct clutch control valve in response to a signal transmitted from the TCM.

Supply power to the TCM.

The TCM transmits shift position signal to the combination meter via CAN communication line.

Refer to " SYSTEM DESCRIPTION ".

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