P1778

Description

- The step motor's 4 aspects of ON/OFF change 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 electrical system is OK, but mechanical system is NG.
- This diagnosis item is detected when the state of the changing the speed mechanism in unit does not operate normally.


CONSULT Reference Value

Remarks: Specification data are reference values.







On Board Diagnosis Logic

- This is an OBD-II self-diagnostic item.
- Diagnostic trouble code "P1778" with CONSULT is detected under the following conditions.
- When not changing the pulley ratio according to the instruction of TCM.


Possible Cause

Step motor


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" on "DATA MONITOR MODE".
- If hi-geared fixation occurred, go to .
NOTE:
If "DTC Confirmation Procedure" has been previously performed, always turn ignition switch OFF and wait at least 10 seconds before performing the next test.
After the repair, touch "ERASE" on "SELF-DIAG RESULTS" and then perform the following procedure to confirm the malfunction is eliminated.

WITH CONSULT

1.Turn ignition switch ON and select "DATA MONITOR" mode for "TRANSMISSION" with CONSULT.
2.Make sure that output voltage of CVT fluid temperature sensor is within the range below.

ATF TEMP SEN: 1.0 - 2.0 V
If 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)
3.Select "DATA MONITOR" mode for "TRANSMISSION" with CONSULT.
4.Start engine and maintain the following conditions for at least 30 consecutive seconds.





5.If DTC is detected, go to .

WITH GST

Follow the procedure "WITH CONSULT".


Diagnosis Procedure


1. CHECK STEP MOTOR

With CONSULT
It is monitoring whether "GEAR RATIO: 2.34 - 0.39" changes similarly to "STM STEP: 0 - 177" by DATA MONITOR mode. CVT Trouble Diagnosis.
Without CONSULT
Inspect the engine speed (rise and descend), vehicle speed, throttle position, and check shift change. Refer to
Vehicle Speed When Shifting Gears.
OK or NG
OK-INSPECTION END
NG- Replace the transaxle assembly. Removal And Installation
(MR-20DE), Removal And Installation (QR-25DE).