Check engine code P0740 (torque conv clutch no rpm drop at lockup). Reset the check engine light and then took jeep on highway and it shifted through the gears normally and i could here the rpm's drop everytime even in OD did this several times then all of a sudden light came back on with the same code. What could be cause the light to come on?

This code is set when the transmission control module detects improper voltage at the torque converter clutch. This can be caused by low tranny fluid/dirty tranny fluid/defective torque converter clutch solenoid/electrical connections to from solenoid

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.

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.

Hi there:DTC P0700 is a generic warning code that advice about a transmission fault specific code stored there. In this case, your addicional specifi code is P0740.
DTC P0740 - Torque Converter Clutch control circuit (A/T Torque Converter Clutch - No RPM Drop At Lockup)

This can be caused from as little as a blown fuse or bad ground to a bad valve body in the transmission. I would suggest a transmission shop to further diagnose since there are pressures that need checked and circuits that will need checked with diagnostic equipment. Here is a description and the testing procedure for DTC P0740. Keep in mind that there is a good chance the trans will need rebuilt.

Possible Causes:

Internal transmission component fault (Input or Reaction shaft) Internal transmission leakage (valve body leaking or seal rings) Converter clutch valve or clutch timing valve is sticking TCC assembly has failed.

Hope this helps; also keep in mind that your feedback is important and I`ll appreciate your time and consideration if you leave some testimonial comment about this answer.

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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

Good chance that your TCC (Torque Converter Clutch Solenoid) has gone bad and will need to be replaced. Go to Auto Zone and have them scan the van for the DTC codes, I think the DTC code will be P0740. I looked this up and it's "Torque Converter Clutch lockup"

To check for Converter Clutch lock up, when you are going down the highway about 55 MPH, tap the brake pedal with your lefty foot just enough to make the brake lights come on but not enough to apply the brakes as you keep the gas peddle at the same position. You should get/feel about a 300 RPM rise in the engine. If you don't, then the clutch didn't lock up.

Good luck and thank you for using fixya.

In the '96 Factory Service Manual, it says code P0740 is "Torq Conv Clu, No RPM Drop At Lockup" (Relationship between engine speed and vehicle speed indicates no torque converter clutch engagement).

When I lived in a cold climate (MT) had a JGC,V8, with a trailer towing option that didn't shift correctly in cold temps. The problem was corrected with a TSB that bypassed the tranny cooler @ cold temps.

I've seen several cold weather TSBs having to do with Dodge transmissions at the following: http://dodgeram.info/tsb/group_21.htm

Hope helped.