92 chevy lumina 3.1 Torque convert lock and unlock

Hello, Here is website for the code and possible fixes.
P0740 Chevrolet Torque Converter Clutch Malfunction

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.

Thats sounds alot like your torque converter

P0740 JEEP - Torque Converter Clutch Circuit
Symptoms
- Engine Light ON (or Service Engine Soon Warning Light)
- Transmission shift shock
- Vehicle may not shift into the highest gear

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

When is the code detected?
Torque Converter Clutch (TCC) unlocked for 10 sec., ECM commands converter lock-up and did not record engine speed drop.

P0740 JEEP 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.

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It should shift 4 times. 1-2, 2-3, 3-4 Then you will feel the torque converter clutch lock up which feels like a shift. The torque converter locks to increase gas mileage.

there are several relays for your fan, one the coolent senser , and relay for fan on side wall ,, also replace t-state, at least every other year I have a 94 and have same issue, these little gems seem to have a heat up problem

its just a sensor plug on the tranny, the solenoid reads the speed of the transmission (car) and sends the signal to the computer which identifies that the car has reached proper crusing speed and is not under heavey load (full throttle) it then "locK" the torque converter to not allow any slippage like a standard automatic torque converter, basically making the torque converter act like a clutch,,, thus the name TCC torque converter clutch. So to help you out just unlug the sensor/solenoid and it will stop locking up your converter. Problem solved! MOney saved 2 to 3 hundred bucks!

the transmission band need to be replace

This sounds like a problem with the torque converter lockup system. Usually the torque converter lockup solenoid is at fault in your condition. This solenoid usually locks up the torque convertor (which acts like a clutch in an automatic transmission) when you are driving at a certain speed, and unlocks it when you press the brake, and/or come to a stop. When a torque converter stays locked up, and you stop the vehicle, it acts like a vehicle with a manual transmission, if you bring the vehicle to a complete stop without applying the clutch pedal, the brakes stall the engine. Basically, if the torque converter can't unlock, even when you come to a stop, the engine is still locked to the transmission, and even when you apply the brakes, the torque converter doesn't slip and freewheel like it should, but instead stalls the engine.

yeah i know exactly what it is its one of the transmission solenoids i beleive its called the torque converter circuit