Transmission

Tiny
RAMONA SMALIGO VAUGHN
  • MEMBER
  • 2016 DODGE CARAVAN
  • 2WD
  • AUTOMATIC
  • 82,000 MILES
I got the code P0740 a few months ago and I followed online advice. I replaced the gas cap and the light went off, then a month later check engine came back on with same code. I replaced the purge valve and the light went off. When the light came on again I took it to a transmission guy. He said he replaced something inside the transmission, but the light came back on. I made an appointment for Monday to have my transmission rebuilt, but picked it up to use until then. My light is off. Do I cancel the appointment and pay him for what he fixed so far? Or should I keep the appointment? My car seems to be running fine.
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Saturday, September 12th, 2020 AT 12:01 PM

5 Replies

Tiny
ASEMASTER6371
  • EXPERT
Good afternoon,

The 740 had nothing to do with your previous issue with the evaporate system. They should have been 400 series codes.

https://www.2carpros.com/articles/how-emission-control-systems-work

As far as the 740, what was done so far? He may have just cleared the code but it will return after it fails the drive cycle 3 times.

https://www.2carpros.com/articles/automatic-transmission-problems

I posted the description and possible failures below.

I agree with the shop. Since it indicates the clutches in the torque converter, the metal from that failure goes through the rest of the transmission. I would have it rebuilt. It will eventually fail and leave you stranded.

Roy

P0740-TCC OUT OF RANGE
For a complete wiring diagram, refer to the Wiring Information.

Theory of Operation
The Torque Converter Clutch (TCC) can engaged when certain conditions are met. The TCC piston is electronically modulated by increasing the duty cycle of the TCC solenoid until the torque converter slip difference (difference between engine and transmission input speed) is within 60 rpm. The TCC solenoid is then fully energized (FEMCC 100% duty cycle). Torque converter slip is monitored in FEMCC to ensure adequate clutch capacity.

When Monitored and Set Conditions
When Monitored: This diagnostic runs continuously when the following conditions are met:

During Full EMCC operation.
Transmission is at operating temperature.
Engine temperature is greater than 38 C (100 F).
Throttle Position Sensor is less than 30 .
Brakes are not applied.
Set Conditions:

Torque Converter Clutch solenoid achieves the 85% duty cycle when in Partial EMCC for 10 seconds and three occurrences.
When in full EMCC mode and the and the engine slips the Torque Converter Clutch greater than 100 RPM for 10 seconds and three occurrences.
Default Actions:

MIL will be illuminated.

Possible Causes
TORQUE CONVERTER CLUTCH
TORQUE CONVERTER CLUTCH SOLENOID
BLOCKED ORIFICES
Always perform the PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE before proceeding.

1. CHECK IF RELATED DTCS ARE PRESENT

With the scan tool, read DTCs.

Are DTCs P2763 and/or P2764 also present?

Yes
(Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Diagnosis and Testing) and perform the appropriate diagnostic procedure.

No
Go To 2

2. CHECK IF THE DTC IS CURRENT

Turn the Ignition ON, Engine not running.
With the scan tool, record and erase DTCs.
Drive the vehicle until it is fully warmed up to at least 43 C (110 F).
Perform the following step three times.
Drive the vehicle at 80 Km/h (50 mph) and maintain constant speed for at least 10 seconds. Close the throttle, then tip back in until the throttle angle is between 25 and 29 degrees. Note that if you go over 30 degrees, you must back off of the throttle and retry.

Did the TCC engage during any of the attempts?

Yes
Go To 3

No
Repair the internal transmission components and replace Torque Convertor as necessary.
Perform the appropriate TRANSMISSION VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

3. CHECK VEHICLE HISTORY

Check vehicle repair history for multiple occurrences of DTC P0740 that could not be duplicated and no repairs were performed.

Has the vehicle had recent multiple occurrences of P0740 which could not be duplicated?

Yes

NOTE: If vehicle is under warranty, verify if current policy allows for Valve Body disassembly prior to disassembling the Valve Body.
Remove the Valve Body and inspect TCC valves for debris, sticking or oversized bores. (Refer to 21 - Transmission and Transfer Case/Automatic - 62TE/VALVE BODY/Removal) .
Repair or replace Valve Body as required, if debris is found, repair the source of the debris in accordance with the Service Information.
Perform the appropriate TRANSMISSION VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

No
Go To 4

4. CHECK THE WIRING AND CONNECTORS

The conditions necessary to set the DTC are not present at this time.
Using the schematics as a guide, inspect the wiring and connectors specific to this circuit.
Wiggle the wiring and connectors while checking for shorted and open circuits.
This DTC can also be set under extreme temperature conditions. This is usually caused by an internal problem. Verify if the problem is only experienced under extreme hot or cold conditions.
With the scan tool, check the Event Data to help identify the conditions in which the DTC was set.
Check for Service Information Tune-ups or Service Bulletins for any possible causes that may apply.

Were there any problems found?

Yes
Repair as necessary.
Perform the appropriate TRANSMISSION VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Power-train Control (PCM) - Standard Procedure).

No
Test Complete.
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Saturday, September 12th, 2020 AT 1:11 PM
Tiny
RAMONA SMALIGO VAUGHN
  • MEMBER
Wow. Thank you so much for your answer.
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Saturday, September 12th, 2020 AT 1:28 PM
Tiny
ASEMASTER6371
  • EXPERT
You are welcome.

Always glad to help.

Roy
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Saturday, September 12th, 2020 AT 1:33 PM
Tiny
RAMONA SMALIGO VAUGHN
  • MEMBER
If you need any gardening tips, let me know. ;)
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Saturday, September 12th, 2020 AT 3:12 PM
Tiny
ASEMASTER6371
  • EXPERT
Thank you.

Roy
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Saturday, September 12th, 2020 AT 3:14 PM

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