Infiniti QX56 (Z62). Manual - part 1287

SYSTEM

TM-57

< SYSTEM DESCRIPTION >

[7AT: RE7R01B]

C

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P

Lock-up Operation Condition Table

Lock-up released

• 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

• 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 con-
verter 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

• 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

• 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.

A/T SHIFT LOCK SYSTEM

JSDIA0847GB

Selector lever

“D” position

“M” position

Gear  position

7

6

5

4

3

2

7

6

5

4

3

2

Lock-up

×

–

–

–

–

–

×

×

×

×

×

×

Slip lock-up

×

×

×

×

×

×

×

×

×

×

×

×

TM-58

< SYSTEM DESCRIPTION >

[7AT: RE7R01B]

SYSTEM

A/T SHIFT LOCK SYSTEM : System Description

INFOID:0000000006226779

The selector lever cannot be shifted from the “P” position unless the
brake pedal is depressed while the ignition switch is set to ON. The
shift lock is unlocked by turning the shift lock solenoid ON when the
ignition switch is set to ON, the park position switch is turned ON
(selector lever is in “P” position), and the stop lamp switch is turned
ON (brake pedal is depressed) as shown in the operation chart in the
figure. Therefore, the shift lock solenoid receives no ON signal and
the shift lock remains locked if all of the above conditions are not ful-
filled. (However, selector operation is allowed if the shift lock release
button is pressed.)

SHIFT LOCK OPERATION AT “P” POSITION

When Brake Pedal Is Not Depressed (No Selector Operation Allowed)

The shift lock solenoid (A) is turned OFF (not energized) and the
solenoid rod (B) is extended with the spring when the brake pedal is
not depressed (no selector operation allowed) with the ignition
switch ON.
The connecting lock lever (C) is located at the position shown in the
figure when the solenoid rod is extended. It prevents the movement
of the detent rod (D). For these reasons, the selector lever cannot be
shifted from the “P” position. 

When Brake Pedal Is Depressed (Shift Operation Allowed)

The shift lock solenoid (A) is turned ON (energized) when the brake
pedal is depressed with the ignition switch ON. The solenoid rod (B)
is compressed by the electromagnetic force. The connecting lock
lever (C) rotates when the solenoid is activated. Therefore, the
detent rod (D) can be moved. For these reasons, the selector lever
can be shifted to other positions. 

“P” POSITION HOLD MECHANISM (IGNITION SWITCH LOCK)

JPDIA0624GB

JPDIA0612ZZ

JPDIA0613ZZ

SYSTEM

TM-59

< SYSTEM DESCRIPTION >

[7AT: RE7R01B]

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The shift lock solenoid (A) is not energized when the ignition switch
is in any position other than ON. In this condition, the shift mecha-
nism is locked and “P” position is held. The operation cannot be per-
formed from “P” position if the brake pedal is depressed with the
ignition switch ON when the operation system of shift lock solenoid is
malfunctioning. However, the lock lever (B) is forcibly rotated and the
shift lock is released when the shift lock release button (C) is
pressed from above. Then the selector operation from “P” position
can be performed. 

CAUTION:

Use the shift lock release button only when the selector lever cannot be operated even if the brake
pedal is depressed with the ignition switch ON. 

D

: Detent rod

JPDIA0614ZZ

TM-60

< SYSTEM DESCRIPTION >

[7AT: RE7R01B]

ON BOARD DIAGNOSTIC (OBD) SYSTEM

ON BOARD DIAGNOSTIC (OBD) SYSTEM

Diagnosis Description

INFOID:0000000006226780

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 MI (malfunction indicator) 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 

TM-

78, "DTC Index"

.

OBD FUNCTION

The ECM provides emission-related on board diagnostic (OBD-II) functions for the A/T system.
One function is to receive a signal from the TCM used with OBD-related parts of the A/T system. The signal is
sent to the ECM when a malfunction occurs in the corresponding OBD-related part.
The other function is to indicate a diagnostic result by means of the MI (malfunction indicator) on the instru-
ment panel. Sensors, switches and solenoid valves are used as sensing elements.
The MI automatically illuminates in “One or Two Trip Detection Logic” when a malfunction is sensed in relation
to A/T system parts. For details, refer to 

EC-52, "DIAGNOSIS DESCRIPTION : 1st Trip Detection Logic and

Two Trip Detection Logic"

.