[Previous] [Next]

DTC P1777: Malfunction of Stepper Motor













DIAGNOSTIC FUNCTION


TCM conducts fault detection by monitoring the voltage of each coil for stepper motors.

DESCRIPTIONS OF MONITOR METHODS




MONITOR EXECUTION




MONITOR EXECUTION CONDITIONS (OTHER MONITOR AND SENSOR)


Other Monitor (There is no temporary DTC stored in memory for the item monitored below)
Sensor (The sensor below is determined to be normal)

LOGIC FLOW CHARTS (Monitor Sequence)





DTC SET CONDITIONS


Judgment Criteria

OBD-II DRIVE CYCLE PATTERN


Ignition switch : ON (start the engine and keep it for 10 seconds or more)

PROBABLE CAUSES




DIAGNOSTIC PROCEDURE


STEP 1. Check the following connector:



  • B-08 CVT assembly connector
  • C-40 TCM 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 ground in the wiring harness between the TCM connector and the stepper motor.



  • Between TCM connector (terminal No.40) and body ground
  • Between TCM connector (terminal No.41) and body ground
  • Between TCM connector (terminal No.51) and body ground
  • Between TCM connector (terminal No.52) and body ground
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 ground in the wiring harness between TCM and the stepper motor



  • Between C-40 TCM connector (terminal No.40) and B-08 CVT assembly connector (terminal No.8)
  • Between C-40 TCM connector (terminal No.41) and B-08 CVT assembly connector (terminal No.9)
  • Between C-40 TCM connector (terminal No.51) and B-08 CVT assembly connector (terminal No.10)
  • Between C-40 TCM connector (terminal No.52) and B-08 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 ground.

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 TCM.