P0740 diagnostic code torque convertor clutch solenoid circuit 1999 Volvo V70 - idles fine, but when I put it in gear it runs rough and stalls - once moving it runs fine. Get the P0740 code. Any troubleshooting hints? What should I expect from a mechanic working on this problem? Rob [email protected]

codes are OBDll and are available on line free
example P0740 P0740 is a diagnostic trouble code (DTC) for Torque Converter Clutch Circuit Malfunction

https://www.yourmechanic.com/article/p0421-obd-ii-trouble-code-torque-converter-clutch-circuit-malfunction-by-andrew-quinn

https://www.repairsmith.com/estimates/trouble-codes/p0740/

On some cars, there is a TCC solenoid in the transmission which can be replaced by removing the bottom pan. In some cars this solenoid can't be accessed without major disassembly.

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.

Go here - www.jeepforum.com/forum/f11/tech-faq-links-tsbs-89273/ - and find the AW-4 Service and Diagnostic Manual. Looks like you need to test some solenoids.

P0740 (M)Torq Con Clutch, No RPM Drop at Lockup. Relationship between engine and vehicle speeds indicated failure of torque convertor clutch lock-up system (TCC/PTU solenoid)
P0743 (M)Torque Converter Clutch Solenoid/ Trans Relay Circuits. An open or shorted condition detected in the torque convertor clutch (part throttle unlock) solenoid control circuit. Shift solenoid C electrical fault - Asin transmission
P0743 (M)Torque Converter Clutch Solenoid/ Trans Relay Circuits. An open or shorted condition detected in the torque convertor part throttle unlock solenoid control circuit (3 or 4-speed auto. trans. only).__________________
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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.

p0740 code is torque converter clutch solenoid circuit.hope this helps.

P0740-TORQUE CONVERTER CLUTCH CONTROL CIRCUIT...

POSSIBLE CAUSES:

RELATED DTC P0750 PRESENT
INTERMITTENT WIRING AND/or CONNECTORS
INCORRECT FLUID LEVEL
INTERNAL TRANSMISSION PROBLEM - TCC OUT OF RANGE
L/R SOLENOID INOPERATIVE

Further diagnostic with a good scan tool will help, could be all you need is a new solenoid or some electrical repairs. Hope this helps.

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.

I’m happy to help further over the phone at https://www.6ya.com/expert/jeremy_69f3cc28d95bf514

PO740 is a TCC/lockup code.TCC stands for Torque Convertor Clutch.In between the engine and transmission is a torque convertor.Inside the torque convertor is a clutch.This clutch engages to eliminate slippage inside the torque convertor.When a malfunction occurs in the system,which is activated by solenoids,and a computer,a TCC code will set.There is a diagnostic route specifically for that code,to determine if the malfunction is electrical,mechanical,or hydraulic.

HI
it is automatic transmission fault it refer to :-
torque converter clutch (TCC)solenoid -circuit malfunction
the most cause is :-wiring , TCC solenoid & the transmission control unit ( ECM\PCM\TCM )

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