P0740

DTC P0740: Problem in Lock-up Control System

NOTE:
^ Record all freeze data and review General Troubleshooting Information before you troubleshoot.
^ Keep these replacement solenoid valves on hand:
- Torque converter clutch solenoid valve
- A/T clutch pressure control solenoid valve C

1. Check whether the OBD II scan tool indicates another code.
Does the OBD II scan tool indicate another code?
YES-Perform the troubleshooting flowchart for the indicated code(s). Recheck for code P0740 after troubleshooting.
NO-Go to step 2.

NOTE: Do not continue with this troubleshooting until the causes of any other DTCs have been corrected.

2. Measure the line pressure.
Is the line pressure within the service limit?
YES-Go to step 3.
NO-Replace the transmission.
3. Replace the torque converter clutch solenoid valve.
4. Replace the A/T clutch pressure control solenoid valve C.
5. Turn the ignition switch OFF, and reset the PCM memory with the PGM Tester or by removing the No. 13 fuse in the passenger's under-dash fuse/relay box for more than 10 seconds. Perform the idle learn procedure. If fuse No. 13 was removed, perform the power window control unit reset procedure.
6. Using the scan tool, check to be sure that the engine coolant temperature is 176°F (80°C) or above.
7. Drive the vehicle under the same conditions as those indicated by the freeze data for more than 1 minute, or drive the vehicle at 55 mph (88 km/h) with TPS voltage 0.8 V for more than 1 minute.
8. Recheck for code P0740.
Does the OBD II scan tool indicate code P0740?
YES-Inspect the O-ring on the torque converter.
^ If the O-ring is missing, replace the O-ring.
^ If the O-ring is damaged or OK, replace the transmission and torque converter.
NO-The system is OK at this time.