P1777
DTC P1777: Malfunction of Stepper MotorSTEPPER MOTOR SYSTEM CIRCUIT
DIAGNOSTIC FUNCTION
TCM conducts fault detection by monitoring the voltage of each coil for stepper motors.
DESCRIPTIONS OF MONITOR METHODS
^ The specified voltage is not applied to each coil for stepper motors for 0.2 second because of an open or short circuit.
MONITOR EXECUTION
^ Continuous
MONITOR EXECUTION CONDITIONS (OTHER MONITOR AND SENSOR)
Other Monitor (There is no temporary DTC stored in memory for the item monitored below)
^ P0741: Abnormality in lockup function
^ P0746: Abnormality in hydraulic control system function
^ P0841: Abnormality in line pressure sensor function
^ P0868: Secondary pressure drop
Sensor (The sensor below is determined to be normal)
^ Not applicable
LOGIC FLOW CHARTS (Monitor Sequence)
DTC SET CONDITIONS
Judgment Criteria
^ Stepping motor activation command (ON voltage): 2.8 volts or less. (0.2 second)
^ Stepping motor activation command (OFF voltage): More than 2.8 volts. (0.2 second)
OBD-II DRIVE CYCLE PATTERN
Ignition switch: ON (start the engine and keep it for 10 seconds or more)
PROBABLE CAUSES
^ Malfunction of valve body assembly (Faulty step per motor)
^ Damaged wiring harness and connectors
^ Malfunction of TCM
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?
YES: Go to Step 2.
NO: 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 Q.
Q: Is the check result normal?
YES: Go to Step 4.
NO: 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?
YES: Replace the valve body assembly.
NO: Repair the wiring harness.
STEP 4. Symptom recheck after erasing diagnosis code
Q: Is the check result normal?
YES: Intermittent malfunction
NO: Replace TCM.