P1778

P1778 STEP MOTOR





Description
- 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 Logic

DTC DETECTION LOGIC






DTC CONFIRMATION PROCEDURE

CAUTION:
- 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 P1778.

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
With CONSULT-III
1. Turn ignition switch ON.
2. Select "Data Monitor" in "TRANSMISSION".
3. Check that output voltage of CVT fluid temperature sensor is within the range below.





4. Start engine and maintain the following conditions for at least 30 consecutive seconds.





With GST
Follow the procedure "With CONSULT-III".
Is "P1778" detected?
YES - Go to P1778.
NO - Check intermittent incident. Intermittent Incident.




Diagnosis Procedure
1.CHECK STEP MOTOR SYSTEM
Check step motor system. P1777.
Is the inspection result normal?
YES - GO TO 2.
NO - Repair or replace damaged parts.
2.CHECK PRIMARY SPEED SENSOR SYSTEM
Check primary speed sensor system. P0715.
Is the inspection result normal?
YES - GO TO 3.
NO - Repair or replace damaged parts.
3.CHECK SECONDARY SPEED SENSOR SYSTEM
Check secondary speed sensor system. P0720.
Is the inspection result normal?
YES - GO TO 4.
NO - Repair or replace damaged parts.
4.DETECT MALFUNCTIONING ITEMS
Check TCM connector pin terminals for damage or loose connection with harness connector.
Is the inspection result normal?
YES - Replace TCM. Exploded View.
NO - Repair or replace damaged parts.