Automatic Transmission: Overview Nissan Pathfinder III

SYSTEM DESCRIPTION

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 error 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 independent). 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. For details, refer to " CAN SYSTEM SPECIFICATION CHART ".

DESCRIPTION

The MIL is located on the instrument panel.

Scheme 1

1. The MIL will light up when the ignition switch is turned "ON" without the engine running. This is a bulb check. If the MIL does not light up, refer to " «WARNING LAMPS»(ref-272548-S10854656122007112100000) ".
2. When the engine is started, the MIL should go off. If the MIL remains on, the on board diagnostic system has detected an engine system malfunction. see scheme 47: "SERVICE ENGINE SOON" Malfunction Indicator Lamp

1. The road test inspects overall performance of the A/T and analyzes possible malfunction causes.
2. The road test is carried out in the following three stages.

1. Check before engine is started. Refer to «CHECK BEFORE ENGINE IS STARTED»(ref-272543-S28411640162007112100000) .
2. Check at idle. Refer to «CHECK BEFORE ENGINE IS STARTED»(ref-272543-S28411640162007112100000) .
3. Cruise test Inspect all the items from Part 1 to Part 3. Refer to «CRUISE TEST - PART 1»(ref-272543-S38128836212007112100000) , «CRUISE TEST - PART 2»(ref-272543-S26591612152007112100000) , «CRUISE TEST - PART 3»(ref-272543-S15456843992007112100000) .

1. Before beginning the road test, check the test procedure and inspection items.
2. Test all inspection items until the symptom is uncovered. Diagnose NG items when all road tests are complete.

Operation Procedure

After performing " SELF-DIAGNOSTIC RESULT MODE ", place check marks for results on the " DIAGNOSTIC WORKSHEET ". Reference pages are provided following the items.

1. Touch "SELF-DIAG RESULTS" on "SELECT DIAG MODE" screen. Display shows malfunction experienced since the last erasing operation. see scheme 66: Identifying CONSULT II Display - SELF-DIAG RESULTS

When the ignition switch is switched "ON", the O/D OFF indicator lamp lights up for 2 seconds. As a method for locating the suspect circuit, when the self-diagnostics start signal is input, the memory for the malfunction location is output and the O/D OFF indicator lamp flashes to display the corresponding DTC.

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 independent). 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.

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

The TCM consists of a microcomputer and connectors for signal input and output and for power supply. The TCM controls the A/T.

1. The park/neutral position (PNP) switch includes a transmission position switch.
2. The transmission range switch detects the selector lever position and sends a signal to the TCM.

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

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

The engine speed signal is sent from the ECM to the TCM.

1. The torque converter clutch solenoid valve is activated, with the gear in D4, D5 by the TCM in response to signals sent from the vehicle speed sensor and accelerator pedal position sensor (throttle 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 1/8) 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 shift into 5th gear position or the torque converter clutch does not lock-up as instructed by the TCM. 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 sent from the TCM.

Electric throttle control actuator consists of throttle control motor, accelerator pedal position sensor, throttle position sensor, etc. The actuator sends a signal to the ECM, and ECM sends signals to TCM with CAN communication.

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

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

1. Fail-safe function to detect interlock conditions.

Fail-safe function to prevent sudden decrease in speed by engine brake other than at "1" position.

Input clutch solenoid valve is controlled by the TCM in response to signals sent from the PNP switch, vehicle speed sensor and accelerator pedal position sensor (throttle position sensor). Gears will then be shifted to the optimum position.

1. Input clutch solenoid valve is controlled by the TCM in response to signals sent from the PNP switch, vehicle speed sensor and accelerator pedal position sensor (throttle position sensor). Gears will then be shifted to the optimum position.
2. 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.

Front brake solenoid valve is controlled by the TCM in response to signals sent from the PNP switch, vehicle speed sensor and accelerator pedal position sensor (throttle position sensor). Gears will then be shifted to the optimum position.

1. Front brake solenoid valve is controlled by the TCM in response to signals sent from the PNP switch, vehicle speed sensor and accelerator pedal position sensor (throttle position sensor). Gears will then be shifted to the optimum position.
2. 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.

Direct clutch solenoid valve is controlled by the TCM in response to signals sent from the PNP switch, vehicle speed sensor and accelerator pedal position sensor (throttle position sensor). Gears will then be shifted to the optimum position.

1. Direct clutch solenoid valve is controlled by the TCM in response to signals sent from the PNP switch, vehicle speed sensor and accelerator pedal position sensor (throttle position sensor). Gears will then be shifted to the optimum position.
2. 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.

High and low reverse clutch solenoid valve is controlled by the TCM in response to signals sent from the PNP switch, vehicle speed sensor and accelerator pedal position sensor (throttle position sensor). Gears will then be shifted to the optimum position.

1. High and low reverse clutch solenoid valve is controlled by the TCM in response to signals sent from the PNP switch, vehicle speed sensor and accelerator pedal position sensor (throttle position sensor). Gears will then be shifted to the optimum position.
2. 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.

Low coast brake solenoid valve is turned "ON" or "OFF" by the TCM in response to signals sent from the PNP switch, vehicle speed sensor and accelerator pedal position sensor (throttle position sensor). Gears will then be shifted to the optimum position.

1. Low coast brake solenoid valve is turned "ON" or "OFF" by the TCM in response to signals sent from the PNP switch, vehicle speed sensor and accelerator pedal position sensor (throttle position sensor). Gears will then be shifted to the optimum position.
2. 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.

Fail-safe function to detect front brake clutch solenoid valve condition.

Fail-safe function to detect input clutch solenoid valve condition.

Fail-safe function to detect direct clutch solenoid valve condition.

Fail-safe function to detect high and low reverse clutch solenoid valve condition.

1. The mechanical key interlock mechanism also operates as a shift lock: With the ignition switch turned to ON, the selector lever cannot be shifted from "P" (parking) to any other position unless the brake pedal is depressed. With the key removed, the selector lever cannot be shifted from "P" to any other position. The key cannot be removed unless the selector lever is placed in "P" position.
2. The shift lock and key interlock mechanisms are controlled by the ON-OFF operation of the shift lock solenoid and by the operation of the rotator and slider located inside the key cylinder, respectively.

Scheme 2