[Previous][Next]
DTC P1740: Malfunction of Lockup/Select Switching Solenoid Valve
 
 
 
 
SOLENOID VALVE SYSTEM CIRCUIT
Refer to .
 
 
DIAGNOSTIC FUNCTION
TCM detects abnormal operation of the lockup/select switching solenoid valve.
 
 
DESCRIPTIONS OF MONITOR METHODS
  • Specified amount of current is not flown to the lockup/select switching solenoid valve 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)
  • P0740: Malfunction of lockup solenoid valve
  • P0745: Malfunction of line pressure solenoid valve
  • P0840: Malfunction of secondary pressure sensor
Sensor (The sensor below is determined to be normal)
  • Secondary pressure sensor
 
 
LOGIC FLOW CHARTS (Monitor Sequence)
 
 
DTC SET CONDITIONS
Judgment Criteria
  • Lockup/select switching solenoid valve activation command (ON voltage): 3.7 volts or less (0.2 second)
  • Lockup/select switching solenoid valve activation command (OFF voltage): more than 3.7 volts (0.5 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 lockup/select switching solenoid valve)
  • Damaged wiring harness and connectors
  • Malfunction of TCM
 
 
DIAGNOSIS
STEP 1. Scan tool data list
  • Item 36: LU/SEL changeover SOL. output
  • Item 37: LU/SEL changeover SOL. monitor
OK: Check that the output and monitor do not differ greatly.
Is the check result normal?
Intermittent malfunction
Go to Step 2.
 
STEP 2. Check the following connector:
  • B-120 CVT assembly connector
  • A-16 Intermediate connector
  • C-131 TCM connector
Check the terminals for a contact status problem and internal short circuit.
Is the check result normal?
Go to Step 3.
Repair the defective connector.
 
STEP 3. Check for open circuit and short to ground in the wiring harness between the TCM connector and the CVT assembly connector.
Between C-131 TCM connector (terminal No.14) and B-120 CVT assembly connector (terminal No.4)
Is the check result normal?
Go to Step 4.
Repair the wiring harness.
 
STEP 4. Lockup/select switching solenoid valve single unit check
Refer to .
Is the check result normal?
Go to Step 5.
Replace the valve body assembly.
 
STEP 5. Symptom recheck after erasing diagnostic trouble code
Is the check result normal?
Intermittent malfunction
Replace TCM.