Nissan Versa (N17): A/T control system

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.

TCM HIGH TEMPERATURE PROTECTION CONTROL

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

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.

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.