Code No. P1777: Malfunction of Stepper Motor










DIAGNOSTIC FUNCTION



JUDGEMENT CRITERIA



PROBABLE CAUSES



  • Malfunction of valve body assembly (Faulty stepper motor)
  • Damaged wiring harness and connectors
  • Malfunction of CVT-ECU

DIAGNOSTIC PROCEDURE

STEP 1. Check the following connector:

  • B-118 CVT assembly connector
  • C-33 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-33 CVT-ECU connector (terminal No. 40) and B-118 CVT assembly connector (terminal No. 8)
  • Between C-33 CVT-ECU connector (terminal No. 41) and B-118 CVT assembly connector (terminal No. 9)
  • Between C-33 CVT-ECU connector (terminal No. 51) and B-118 CVT assembly connector (terminal No. 10)
  • Between C-33 CVT-ECU connector (terminal No. 52) and B-118 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.