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.
- Check primary speed and vehicle speed before perform "DTC CONFIRMATION PROCEDURE".
- If hi-geared fixation occurred, go to "Diagnosis Procedure" .

1. PRECONDITIONING

If "DTC CONFIRMATION PROCEDURE" has been previously conducted, always turn ignition switch OFF and wait at least 10 seconds before conducting the next test.
- GO TO 2.

2. CHECK DTC DETECTION

With CONSULT
1.Start the engine.
2.Warm up the engine. [Set the CVT fluid to 20�C (68�F) or more.]
NOTE:
When the ambient temperature is 20�C (68�F), the CVT fluid usually increases to 50 to 80�C (122 to
176�F) with driving in an urban area for approximately 10 minutes.
3.Maintain the following conditions for at least 30 seconds.





With GST
Follow the procedure "With CONSULT".
Is "P1778" detected?
YES- Go to "Diagnosis Procedure" .
NO- INSPECTION END


Diagnosis Procedure


1. CHECK STEP MOTOR SYSTEM

Revision: March 20122013 Infiniti JX
Check step motor system. Refer to "Diagnosis Procedure" P1777.
Is the inspection result normal?
YES- GO TO 2.
NO- Repair or replace damaged parts.

2. CHECK SECONDARY SPEED SENSOR SYSTEM

Check secondary speed sensor system. Refer to "Diagnosis Procedure" P0720.
Is the inspection result normal?
YES- GO TO 3.
NO- Repair or replace damaged parts.

3. CHECK PRIMARY SPEED SENSOR SYSTEM

Check primary speed sensor system. Refer to "Diagnosis Procedure" P0715.
Is the inspection result normal?
YES- GO TO 4.
NO- Repair or replace damaged parts.

4. CHECK INTERMITTENT INCIDENT

Refer to "Intermittent Incident" Intermittent Incident.
Is the inspection result normal?
YES- Replace transaxle assembly. Refer to "Removal and Installation" Removal and Installation.
NO- Repair or replace damaged parts.
Revision: March 20122013 Infiniti JX