Code No. P1777: Malfunction of Stepper Motor












DIAGNOSTIC FUNCTION


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

JUDGMENT 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 the following connector:

  • B-119 CVT assembly connector
  • C-135 CVT-ECU connector
Check the terminals for a contact status problem and internal short circuit.

Q. Is the check result normal?
Go to Step 2.
Repair the defective connector.

STEP 2. Check for open circuit and short to earth in the wiring harness between the CVT-ECU connector and the stepper motor.

  • Between CVT-ECU connector (terminal No. 40) and body earth
  • Between CVT-ECU connector (terminal No. 41) and body earth
  • Between CVT-ECU connector (terminal No. 51) and body earth
  • Between CVT-ECU connector (terminal No. 52) and body earth
OK: Resistance value is approximately 15 Ω.

Q. Is the check result normal?
Go to Step 4.
Go to Step 3.

STEP 3. Check for open circuit and short to earth in the wiring harness between CVT-ECU and the stepper motor

  • Between C-135 CVT-ECU connector (terminal No. 40) and B-119 CVT assembly connector (terminal No. 8)
  • Between C-135 CVT-ECU connector (terminal No. 41) and B-119 CVT assembly connector (terminal No. 9)
  • Between C-135 CVT-ECU connector (terminal No. 51) and B-119 CVT assembly connector (terminal No. 10)
  • Between C-135 CVT-ECU connector (terminal No. 52) and B-119 CVT assembly connector (terminal No. 11)
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 wiring harness.

STEP 4. Symptom recheck after erasing diagnosis code

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