Nissan Maxima Service and Repair Manual: P1778 step motor
The step motor changes the step by turning 4 coils ON/OFF according to the signal from TCM. As a result, the flow of line pressure to primary pulley is changed and pulley ratio is controlled.
This diagnosis item is detected when the electrical system is OK, but the mechanical system is NG.
This diagnosis item is detected when the state of the changing of the speed mechanism in the unit does not operate normally.
DTC DETECTION LOGIC
DTC CONFIRMATION PROCEDURE
Always drive vehicle at a safe speed.
Before starting "DTC CONFIRMATION PROCEDURE", confirm "Hi" or "Mid" or "Low" fixation by "PRI SPEED" and "VEHICLE SPEED" in "Data Monitor".
If hi-geared fixation occurred, go to TM-112, "Diagnosis Procedure".
NOTE: Immediately after performing any "DTC CONFIRMATION PROCEDURE", always turn ignition switch OFF.
Then wait at least 10 seconds before performing the next test.
1.CHECK DTC DETECTION
Turn ignition switch ON.
Select "Data Monitor" in "TRANSMISSION".
Check that output voltage of CVT fluid temperature sensor is within the range below.
ATF TEMP SEN : 1.0 - 2.0 V
If it is out of range, drive the vehicle to decrease the voltage (warm up the fluid) or stop engine to increase the voltage (cool down the fluid)
4. Start engine and maintain the following conditions for at least 30 consecutive seconds.
Start test from 0 km/h (0 MPH)
Constant acceleration : Keep 30 seconds or more
VEHICLE SPEED : 10 km/h (6 MPH) or more
ACC PEDAL OPEN : More than 1.0/8
RANGE : "D" position
ENG SPEED : 450 rpm or more
Follow the procedure "With CONSULT".
1.CHECK STEP MOTOR SYSTEM
Check step motor system. Refer to TM-109, "DTC Logic".
2.CHECK PRIMARY SPEED SENSOR SYSTEM
Check primary speed sensor system. Refer to TM-57, "DTC Logic".
3.CHECK SECONDARY SPEED SENSOR SYSTEM
Check secondary speed sensor system. Refer to TM-60, "DTC Logic".
4.DETECT MALFUNCTIONING ITEMS
Check TCM connector pin terminals for damage or loose connection with harness connector.