P1777

P1777 STEP MOTOR

Description

- The step motor is included in the control valve assembly.
- The step motor changes the step with 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


CONSULT Reference Value in Data Monitor Mode

Remarks: Specification data are reference values.







On Board Diagnosis Logic

- This is an OBD-II self-diagnostic item.
- Diagnostic trouble code "P1777" with CONSULT is detected under the following conditions.
- When operating step motor ON and OFF, there is no proper change in the voltage of TCM terminal which corresponds to it.


Possible Cause

- Step motor
- Harness or connectors (Step motor circuit is open or shorted.)


DTC Confirmation Procedure


CAUTION:
Always drive vehicle at a safe speed.
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.Drive vehicle for at least 5 consecutive seconds.
3.If DTC is detected, go to .

WITH GST

Follow the procedure "WITH CONSULT".


Wiring Diagram - CVT - STM







TCM TERMINALS AND REFERENCE VALUES

Trouble Diagnosis.


Diagnosis Procedure


1. CHECK INPUT SIGNALS

With CONSULT
1.Start engine.
2.Select "SELECTION FROM MENU" in "DATA MONITOR" mode for "TRANSMISSION" with CONSULT.
3.Start vehicle and read out the value of "STM STEP", "SMCOIL A", "SMCOIL B", "SMCOIL C", and
"SMCOIL D".





OK or NG
OK- GO TO 4.
NG- GO TO 2.

2. CHECK HARNESS BETWEEN TCM AND STEP MOTOR

1.Turn ignition switch OFF.
2.Disconnect CVT unit connector and TCM connector.





3.Check continuity between TCM connector terminals and CVT
unit harness connector terminals.





4.If OK, check harness for short to ground and short to power.
5.If OK, check continuity between body ground and CVT assembly.
6.Reinstall any part removed.
OK or NG
OK- GO TO 3.
NG- Repair open circuit or short to ground or short to power in harness or connectors.

3. CHECK STEP MOTOR

Check step motor. .
OK or NG
OK- GO TO 4.
NG- Repair or replace damaged parts.

4. CHECK DTC

Perform .
OK or NG
OK-INSPECTION END
NG- GO TO 5.

5. CHECK TCM

1.Check TCM input/output signals. Trouble Diagnosis .
2.If NG, re-check TCM pin terminals for damage or loose connection with harness connector.
OK or NG
OK-INSPECTION END
NG- Repair or replace damaged parts.


Component Inspection


STEP MOTOR

1.Turn ignition switch OFF.
2.Disconnect CVT unit harness connector.





3.Check resistance between CVT unit harness connector terminals and ground.





4.If NG, replace the transaxle assembly. Transaxle Assembly .