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DTC P0746: Abnormality in Hydraulic Control System Function
 
 
 
 
DIAGNOSTIC FUNCTION
If the pulley ratio, which is calculated according to the primary pulley speed and the secondary pulley speed, exceeds the standard value, the TCM determines that the line pressure is abnormal.
 
 
DESCRIPTIONS OF MONITOR METHODS
The ratio between the primary pulley speed and the secondary pulley speed is 2.55 or more for 0.2 second, or 3.35 or more for 0.1 second.
 
 
MONITOR EXECUTION
  • Transmission range: "D", "R" or "L"
  • Primary speed: 500 r/min or more
  • Acceleration: -0.05 G or more
  • Engine speed: 450 r/min or more
 
 
MONITOR EXECUTION CONDITIONS (OTHER MONITOR AND SENSOR)
Other Monitor (There is no temporary DTC stored in memory for the item monitored below)
  • P0705: Malfunction of transmission range switch
  • P0715: Malfunction of primary pulley speed sensor
  • P0720: Abnormality in output speed sensor
  • P0791: Malfunction of the secondary pulley speed sensor
  • U0001: Malfunction of CAN communication
  • U0100: CAN time-out error (Engine)
Sensor (The sensor below is determined to be normal)
  • Transmission range switch
  • Primary pulley speed sensor
  • Output speed sensor
  • Secondary pulley speed sensor
 
 
LOGIC FLOW CHARTS (Monitor Sequence)
 
 
DTC SET CONDITIONS
Check Conditions
  • Transmission range switch position: "D", "R" or "L"
  • Engine speed: 450 r/min or more
  • Primary pulley speed: 500 r/min or more
  • Acceleration: -0.05 G or more
Judgment Criteria
  • Pulley ratio (primary pulley speed/secondary pulley speed) more than 2.55 for 0.2 second.
  • Pulley ratio (primary pulley speed/secondary pulley speed) more than 3.35 for 0.1 second.
 
 
OBD-II DRIVE CYCLE PATTERN
Accelerate to approximately 10 km/h (6.2 mph) slowly. Then drive at a constant speed for 10 seconds.
 
 
PROBABLE CAUSES
  • Malfunction of the valve body assembly (Faulty line pressure solenoid valve)
  • Malfunction of the transaxle assembly
 
 
DIAGNOSIS
Required Special Tools:
  • MB992744: Vehicle communication interface-Lite (V.C.I.-Lite)
  • MB992745: V.C.I.-Lite main harness A
  • MB992747: V.C.I.-Lite USB cable short
  • MB992748: V.C.I.-Lite USB cable long
  • MB991958: Scan Tool (M.U.T.-III Sub Assembly)
    • MB991824: Vehicles Communication Interface (V.C.I.)
    • MB991827: M.U.T.-III USB Cable
    • MB991910: M.U.T.-III Main Harness A (Vehicles with CAN communication system)
STEP 1. Check the following connector.
  • CVT assembly connector
Check the terminals for a contact status problem and internal short circuit.
Is the check result normal?
Go to Step 2.
Repair the faulty connector.
 
STEP 2. Measure the output wave pattern of the line pressure solenoid valve at TCM connector (PLLS terminal).
(1) Connect the CVT assembly connector.
(2) Connect an oscilloscope between TCM connector PLLS terminal and body ground (Refer to ).
(3) Transmission range: "P" range
(4) Engine: Idling
(5) Use an oscilloscope, measure the voltage between TCM connector PLLS terminal and body ground.
OK: A wave pattern such as the one shown on (Check Procedure Using an Oscilloscope) should be output, and the maximum value should be 11 volts or more and the minimum value should be 1 volt or less. There should be no noise in the output wave pattern.
Is the check result normal?
Go to Step 3.
Refer to DTC P0962: Malfunction of the line pressure solenoid valve (short to ground) , or DTC P0963: Malfunction of the line pressure solenoid valve (open circuit/ short to power supply) .
 
STEP 3. Using scan tool (M.U.T.-III), recheck the DTC.
Check again if the DTC is stored.
(1) Erase the DTC.
(2) Turn the ignition switch to the "LOCK" (OFF) position.
(3) Carry out a test drive with the OBD-II drive cycle pattern.
(4) Recheck the DTC.
Is DTC P0746 stored?
Go to Step 4.
The trouble can be an intermittent malfunction (Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).
 
STEP 4. CVT belt inspection.
Check the appearance of the CVT belt. (Refer to On-vehicle Service – CVT Belt Inspection)
Is the CVT belt normal?
Replace valve body assembly. (Refer to ).
Replace the transaxle assembly (Refer to ).