Code No. P1777: Malfunction of Stepper Motor


DIAGNOSTIC FUNCTION


CVT-ECU conducts fault detection by monitoring the voltage of each coil for stepper motors.

JUDGEMENT CRITERIA


The specified voltage is not applied to each coil for stepper motors for 0.2 seconds because of the open or short circuit.

PROBABLE CAUSES



DIAGNOSTIC PROCEDURE

STEP 1. Check for open circuit and short to earth in SPM1, SPM2, SPM3, SPM4 line between the CVT-ECU connector and the CVT assembly (stepper motor)
Between CVT-ECU connector and body earth
OK: Resistance value is approximately 15 Ω.

Q. Is the check result normal?
Go to Step 3.
Go to Step 2.

STEP 2. Check for open circuit and short to earth in SPM1, SPM2, SPM3, SPM4 line between CVT-ECU connector and the CVT assembly (stepper motor)
Check that there is no continuity in both sides of the connectors and that no short circuit is present between the connectors and the body earth.

Q. Is the check result normal?
Replace the valve body assembly.
Repair the connector(s) or wiring harness.

STEP 3. Symptom recheck after erasing diagnosis code

Q. Is the check result normal?
Intermittent malfunction
Replace CVT-ECU.