Nissan Versa (N17): A/T control system

Nissan Versa 2nd generation (N17) Service Manual / Transmission & driveline / Transaxle & transmission (TM) / A/T control system

A/T control system : system diagram

A/T control system : system diagram

A/T control system : system description

SYSTEM DESCRIPTION

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.
Receives input signals transmitted from various switches and sensors.
Determines required line pressure, shifting point, lock-up operation, etc.
Transmits required output signals to the respective solenoids.

INPUT/OUTPUT SIGNAL CHART

Sensor (or signal)		TCM function		Actuator
Engine speed signal Engine torque signal Accelerator pedal position signal Closed throttle position signal Stop lamp switch signal Transmission range switch O/D switch signal A/T fluid temperature sensor Input speed sensor Output speed sensor Vehicle speed signal		Line pressure control (TM) Shift change control (TM) Shift pattern control (TM) Lock-up control (TM) Fail-safe control (TM) Self-diagnosis (TM) CONSULT communication line (TM) CAN communication line (TM)		Line pressure solenoid valve Torque converter clutch solenoid valve Low clutch solenoid valve 2-4 brake solenoid valve High clutch/low & reverse brake solenoid valve Select switch ON-OFF solenoid valve Shift position indicator O/D OFF indicator lamp

INPUT/OUTPUT SIGNAL OF TCM

*: If these input and output signals are different, the TCM triggers the fail-safe function.

A/T control system : fail-safe

TCM is equipped with an electrical fail-safe mode. The operation can be continued even if the signal circuit of the main electronically controlled input/output parts are damaged.

If the vehicle shows following behaviors including "poor acceleration", a malfunction of the applicable system is detected by TCM and the vehicle may be in a fail-safe mode. At this time, check the DTC code and perform inspection and repair according to the malfunction diagnosis procedures.

FAIL-SAFE FUNCTION

A/T control system : protection control

The TCM becomes the protection control status temporarily to protect the safety when the safety of TCM and transmission is lost. It automatically returns to the normal status if the safety is secured.

The TCM is equipped with the following protection control.

REVERSE INHIBIT CONTROL

Intercepts the torque transmission and shifts to the neutral status if the selector lever is shifted to "R" position while the vehicle moves forward at the vehicle speed 10 km/h (7 MPH) or more.

Operation detection conditions	Vehicle speed: 10 km/h (7 MPH) or more (when driving forward) Selector lever is shifted to "R" position.
Control when activated	Neutral
Recovery condition	Vehicle speed: 7 km/h (4 MPH) or less and Engine speed: 2,800 rpm or less
Vehicle behavior	The torque transmission cannot be performed There is a shock just before a vehicle stop

TCM HIGH TEMPERATURE PROTECTION CONTROL

When the ATF becomes hot, the shifting pattern is changed for preventing fluid temperature rise.

Operation detection conditions	ATF temp.: 125C (257F) or more
Control when activated	Change the shift pattern so that higher upshift may be achieved.
Recovery condition	ATF temp.: 119C (246F) or less
Vehicle behavior	Upshifts at a higher vehicle speed than usual.

TORQUE-DOWN CONTROL WHEN CONTINUOUS STALL OCCURS IN D POSITION

If the accelerator pedal is continually depressed for a certain length of time when the selector lever is in the "D" position and the vehicle is parked, the engine output is limited for protecting the transaxle.

Operation detection conditions	The following conditions continue for 20 seconds or more Selector lever is in the "D" position or "R" position and the vehicle is stopped and Engine speed: 2,300 - 2,850 rpm
Control when activated	Limits engine output
Recovery condition	Selector lever is shifted to a position other than "D" or "R" or The accelerator pedal is released
Vehicle behavior	Decreased starting performance Engine speed hunching when the accelerator pedal is depressed

O/D PROHIBIT CONTROL AT LOW TEMPERATURES

When the ATF temperature is low immediately after engine start, shifting to 4GR is prohibited for protecting the transaxle and allowing the exhaust gas characteristics to warm up quickly.

Operation detection conditions	ATF temp.: 0C (32F) or less or ATF temp.: less than 40C (104F) (when IGN is ON) Vehicle speed: 65 km/h (40 MPH) or less 3GR
Control when activated	4GR prohibited
Recovery condition	Less than 130 seconds following IGN ON ATF temp.: 40C (104F) or more or Vehicle speed: 65 km/h (40 MPH) or higher After 130 seconds following IGN ON ATF temp.: 0C (32F) or more
Vehicle behavior	Shifts up only as far as 3GR.

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