DTC P0740

id050200812100

DTC P0740

Torque converter clutch (TCC) system malfunction
DETECTION CONDITION
•  Difference between the engine speed and turbine speed remains "vehicle speed/2+40" rpm or more for 10 s or more during TCC operation in 3GR or 4GR while driving.
(Ex. When driving at a vehicle speed of 100 km/h, the difference will be 100/2+40 = 90 rpm. Therefore, a malfunction will be detected if a speed difference of 90 rpm continues for 10 s or more.)
Diagnostic support note:
•  This is continuous monitor (CCM).
•  MIL illuminates if TCM detects the above malfunction conditions in two consecutive drive cycles.
•  PENDING CODE is available.
•  FREEZE FRAME DATA is available.
•  AT warning light does not illuminate.
•  DTC is stored in TCM memory.
POSSIBLE CAUSE
•  ATF level low
•  Deteriorated ATF
•  TCC solenoid valve and pressure control solenoid valve stuck
•  Line pressure low
•  Oil pump malfunction
•  Control valve stuck
•  Torque convert clutch malfunction
•  TCM malfunction

Diagnostic procedure

STEP

INSPECTION

ACTION
1
VERIFY FREEZE FRAME DATA HAS BEEN RECORDED
•  Has FREEZE FRAME DATA been recorded?
Yes
Go to the next step.
No
Record the FREEZE FRAME DATA on the repair order, then go to the next step.
2
VERIFY RELATED REPAIR INFORMATION AVAILABILITY
•  Verify related Service Information availability.
•  Is any related repair information available?
Yes
Perform repair or diagnosis according to the available repair information.
•  If the vehicle is not repaired, go to the next step.
No
Go to the next step.
3
INSPECT ATF CONDITION
•  Turn the ignition switch to the LOCK position.
•  Inspect ATF condition.
―  Clear red: Normal
―  Milky: Water mixed in fluid
―  Reddish brown: Deteriorated ATF
•  Is it normal?
Yes
Go to the next step.
No
If the ATF color milky or reddish brown, replace ATF, then go to Step 5.
(See AUTOMATIC TRANSMISSION FLUID (ATF) REPLACEMENT.)
4
INSPECT ATF LEVEL
•  Start the engine.
•  Warm up AT.
•  Is the ATF level within the specification?
Yes
Go to the next step.
No
Add ATF to the specified level, then go to Step 9.
(See AUTOMATIC TRANSMISSION FLUID (ATF) INSPECTION.)
5
INSPECT LINE PRESSURE
•  Start the engine.
•  Measure each line pressure.
•  Are the line pressure measurements within the specifications?
Yes
Go to the next step.
No
Inspect or replace the applicable part according to the line pressure test results, then go to Step 9.
6
CLICK TEST OF SOLENOID VALVES
•  Turn the ignition switch to the LOCK position.
•  Disconnect the AT solenoid valve connector.
•  Apply battery voltage to the AT solenoid valve connector terminals.
―  TCC solenoid valve: G
―  pressure control solenoid valve: A
•  Verify the click sounds of the TCC solenoid valve and pressure control solenoid valve.
•  Are there click sounds?
Yes
Go to the next step.
No
Replace the TCC solenoid valve or the pressure control solenoid valve, then go to Step 9.
(See CONTROL VALVE BODY REMOVAL.)
(See CONTROL VALVE BODY INSTALLATION.)
7
INSPECT DIFFERENCE BETWEEN ENGINE SPEED AND TURBINE SPEED
•  Inspect difference between the engine speed and turbine speed during TCC operation in 4GR.
•  Drive the vehicle under the following conditions:
―  TR switch position: D range
―  Gear position: 4GR
―  TCC solenoid valve: ON
•  Is difference between the engine speed (RPM PID) and turbine speed normal?
―  Difference
99 rpm or less
Yes
Go to the next step.
No
Replace the torque converter, then go to Step 9.
(See AUTOMATIC TRANSMISSION REMOVAL/INSTALLATION.)
8
INSPECT OPERATION OF EACH VALVE AND SPRING
•  Remove the control valve body.
•  Disassemble the control valve body.
•  Is operation of each valve and return spring normal?
Yes
Replace the torque converter, then go to the next step.
No
Replace the control valve body, then go to the next step.
(See CONTROL VALVE BODY REMOVAL.)
(See CONTROL VALVE BODY INSTALLATION.)
9
VERIFY TROUBLESHOOTING OF DTC P0740 COMPLETED
•  Make sure to reconnect all disconnected connectors.
•  Clear the DTC from the TCM memory using the M-MDS.
•  Start the engine.
•  Warm up AT.
•  Drive the vehicle under the following conditions for 10 s or more.
―  Vehicle speed (VSS PID): Within 10—87 km/h {6—54 mph}
―  Gear position: 4GR
―  TR switch position: D range
―  TCC solenoid valve: ON
•  Is the PENDING CODE same as the DTC present?
Yes
Replace the TCM, then go to the next step.
(See TCM REMOVAL/INSTALLATION.)
No
Go to the next step.
10
VERIFY AFTER REPAIR PROCEDURE
•  Perform the “After Repair Procedure”.
•  Are any DTCs present?
Yes
Go to the applicable DTC inspection.
(See DTC TABLE [RC4A-EL].)
No
DTC troubleshooting completed.