I have a code 0740 coming up on a 2003 Honda Odyssey, says Torque Converter Clutch Solenoid Circuit Open. Does that mean i can have the Solenoid replaced or does the transmission need to be replaced??

P0700 OBD II Trouble Code Transmission Control System Malfunction...
P0740 Dodge Torque Converter Clutch Circuit
P0430 Dodge Catalyst Efficiency Bank 2

P0740 Honda - Transmission Lock-Up Control System Fault Possible causes
- Low transmission fluid level
- Dirty transmission fluid
- Faulty torque converter clutch solenoid valve
- Torque converter clutch solenoid valve harness is open or shorted
- Torque converter clutch solenoid valve circuit poor electrical connection

Tech notes
On some Honda vehicles the P0740 code may be set by an overheating torque converter problem which is caused by an insufficient flow to the torque converter release circuit.

P0740 Honda Description
The torque converter clutch solenoid valve is activated, with the gear in D4, by the Transmission Control Module (TCM) in response to signals sent from the vehicle speed and the Engine Control Module (ECM). Lock-up piston operation will then be controlled. When the torque converter clutch solenoid valve is activated, the torque converter lockup clutch will engage creating a 1 to 1 RPM ratio between the transmission input shaft and the rotational speed of the torque converter.
Lock-up operation, however, is prohibited when A/T fluid temperature is too low.
When the accelerator pedal is depressed (less than 2/8) in lock-up condition, the engine speed should not change abruptly. If there is a big jump in engine speed, there is no lock-up.

This code refers to the electrical side of the torque converter not the inside workings of the converter itself. Check the electrical connector and harness for opens breaks or chaffing. Most of the times the tcc solenoid replacement will fix this issue.

P0740 - Torque Converter Clutch Malfunctionhttp://engine-codes.com/p0740.htmlForum CodePossible causes- Low transmission fluid level
- Dirty transmission fluid
- Faulty torque converter clutch solenoid valve
- Torque converter clutch solenoid valve harness or connectors
- Torque converter clutch solenoid valve circuit is open or shorted When is the code detected?Diagnostic trouble code P0740 is detected when TCM detects an improper voltage drop when it tries to operate the solenoid valve.

P0700 TCM has requested PCM to run on Check engine light to alert to a fault in the automatic transmission.

You must do the diagnostics for each code.
Here are the possibilitesP0740 DODGE - Torque Converter Clutch Circuithttp://engine-codes.com/p0740_dodge.htmlForum CodePossible causes- Low transmission fluid level
- Dirty transmission fluid
- Faulty torque converter clutch solenoid valve
- Torque converter clutch solenoid valve harness or connectors
- Torque converter clutch solenoid valve circuit is open or shorted
P0743 DODGE - Torque Converter Clutch Solenoid Circuithttp://engine-codes.com/p0743_dodge.htmlForum CodePossible causes- Faulty torque converter clutch solenoid valve
- Torque converter clutch solenoid valve harness or connectors
- Torque converter clutch solenoid valve circuit is open or shorted
- Low transmission fluid level
- Dirty transmission fluid

P0753 DODGEP0753 DODGE - 3-4 Shift Solenoid Relayhttp://engine-codes.com/p0753_dodge.htmlForum CodePossible causes- Faulty shift solenoid valve
- Shift solenoid valve harness or connectors
- Shift solenoid valve circuit is open or shorted
- Low transmission fluid level
- Dirty transmission fluid

Possible causes - Low transmission fluid level
- Dirty transmission fluid
- Faulty torque converter clutch solenoid valve
- Torque converter clutch solenoid valve harness or connectors
- Torque converter clutch solenoid valve circuit is open or shorted
- Transmission internal mechanical problem

P0743 is torque converter circut electrical. Could mean that the lockup solenoid is faulty or connections are bad.

P0740 Torque Converter Clutch Circuit Malfunction
The problem could be the torque converter itself or the sensor circuit for the clutch.
Best to have a Transmission Expert look at it to see if any further damage has occurred.

P0740 is a Torque Converter Clutch Circuit Malfunction, you will need to have just this circuit tested, it is mostly just a defective Torque converter clutch solenoid in the trans or a defective connection to the trans, u do not need another overhaul.