Automatic Transmission: Overview Infiniti QX56 I

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 COMMUNICATION ".

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1. When an input torque signal equivalent to the engine drive force is sent from the ECM to the TCM, the TCM controls the line pressure solenoid.
2. 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.

DESCRIPTION

The MIL is located on the instrument panel.

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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-230067-S04045829642006042700000) ".
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.

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. Check before engine is started. Refer to «CHECK BEFORE ENGINE IS STARTED»(ref-230041-S06814178322006042700000) . Check at idle. Refer to «CHECK BEFORE ENGINE IS STARTED»(ref-230041-S06814178322006042700000) . Cruise test Inspect all the items from Part 1 to Part 3. Refer to «CRUISE TEST - PART 1»(ref-230041-S14464080682006042700000) , «CRUISE TEST - PART 2»(ref-230041-S04067426532006042700000) , «CRUISE TEST - PART 3»(ref-230041-S30857666742006042700000) .
3. Before beginning the road test, check the test procedure and inspection items.
4. 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.

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1. Perform "CONSULT-II SETTING PROCEDURE" Refer to " «CONSULT-II SETTING PROCEDURE»(ref-230041-S18028292242006042700000) ".
2. Touch "SELF-DIAG RESULTS". Display shows malfunction experienced since the last erasing operation.

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*1: Refer to " MALFUNCTION INDICATOR LAMP (MIL) ".

*2: These malfunctions cannot be displayed MIL if another malfunction is assigned to MIL.

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1. Perform "CONSULT-II SETTING PROCEDURE" Refer to " «CONSULT-II SETTING PROCEDURE»(ref-230041-S18028292242006042700000) ".
2. Touch "SELF-DIAG RESULTS".
3. Touch "ERASE". (The self-diagnostic results will be erased.)

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1. Perform "CONSULT-II SETTING PROCEDURE". Refer to " «CONSULT-II SETTING PROCEDURE»(ref-230041-S18028292242006042700000) ".
2. Touch "DATA MONITOR". NOTE: When malfunction is detected, CONSULT-II performs "REAL-TIME DIAGNOSIS". Also, any malfunction detected while in this mode will be displayed at real time.

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1. Perform "CONSULT-II SETTING PROCEDURE". Refer to " «CONSULT-II SETTING PROCEDURE»(ref-230041-S18028292242006042700000) ".
2. Touch "DTC WORK SUPPORT".
3. Touch select item menu.
4. Touch "START".
5. Perform driving test according to "DTC CONFIRMATION PROCEDURE" in "TROUBLE DIAGNOSIS FOR DTC". When testing conditions are satisfied, CONSULT-II screen changes from "OUT OF CONDITION" to "TESTING".
6. Stop vehicle. If "NG" appears on the screen, malfunction may exist. Go to " «DIAGNOSTIC PROCEDURE»(ref-230041-S29214464422006042700000) ".
7. Perform test drive to check gear shift feeling in accordance with instructions displayed.
8. Touch "YES" or "NO".
9. CONSULT-II procedure is ended. If "NG" appears on the screen, a malfunction may exist. Go to " «DIAGNOSTIC PROCEDURE»(ref-230041-S29214464422006042700000) ".

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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.

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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.

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The revolution sensor detects the revolution of the idler gear parking pawl lock 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.

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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.

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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.

The line pressure duty cycle value is not consistent when the closed throttle position signal is "ON". To confirm the line pressure duty cycle at low pressure, the accelerator (throttle) should be open until the closed throttle position signal is "OFF".

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

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

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.

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

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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 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.

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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.

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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.

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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.

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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.

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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.

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On-Board Diagnosis Logic

1. This is an OBD-II self-diagnostic item.
2. Diagnostic trouble code "P1762 D/C SOLENOID/CIRC" with CONSULT-II is detected under the following conditions. When TCM detects an improper voltage drop when it tries to operate the solenoid valve. When TCM detects as irregular by comparing target value with monitor value.

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.

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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.

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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.

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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.

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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.

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

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

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Fail-safe function to detect clutch solenoid valve condition.

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Fail-safe function to detect clutch solenoid valve condition.

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When tow mode switch is "ON", tow mode switch signals are sent to TCM from combination meter by CAN communication line. Then it's a tow mode condition.

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1. CHECK CAN COMMUNICATION LINE Perform the self-diagnosis. Refer to " «SELF-DIAGNOSTIC RESULT MODE»(ref-230041-S05410560772006042700000) ". Is a malfunction in the CAN communication indicated in the results? YES: Check CAN communication line. Refer to " «DTC U1000 CAN COMMUNICATION LINE»(ref-230041-S02653930532006042700000) ". NO: GO TO 2.
2. CHECK POWER SOURCE Turn ignition switch "ON". (Do not start engine.) Check the voltage between tow mode switch connector terminal 1 and ground. OK or NG OK: INSPECTION END NG: GO TO 3.
3. CHECK TOW MODE SWITCH Turn ignition switch "OFF". Disconnect tow mode switch connector. Check continuity between tow mode switch connector M67 terminals 1 and 2. TOW MODE SWITCH CONTINUITY TABLE Condition Continuity Tow mode switch "ON" Yes Tow mode switch "OFF" No OK or NG OK: GO TO 4. NG: Repair or replace tow mode switch.
4. DETECT MALFUNCTIONING ITEM Check the following items. If any items are damaged, repair or replace damaged parts. Harness for short or open between combination meter connector terminal 35 and tow mode switch connector terminal 1. Harness for short or open between tow mode switch connector terminal 2 and ground. OK or NG OK: GO TO 5. NG: Repair or replace damaged parts.
5. CHECK COMBINATION METER Check the combination meter. Refer to " «HOW TO PROCEED WITH TROUBLE DIAGNOSIS»(ref-230067-S00708274062006042700000) ". OK or NG OK: INSPECTION END NO: Repair or replace damaged parts.

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TCM terminals and data are reference value. Measured between each terminal and ground.

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1. The electrical 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".
2. The shift lock and key interlock mechanisms are controlled by the ON-OFF operation of the shift lock sole noid and by the operation of the rotator and slider located inside the key cylinder, respectively.

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