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P0740 - OBD Trouble Code

OBD Code P0740 - Torque Converter Clutch Circuit Malfunction

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OBD-II Code P0740 is also known as a ‘Torque Converter Lockup Malfunction’. It is a generic code and found commonly in OBD-II vehicles. It mainly points out issue present within the transmission range sensor. You may find this code being set along with various other transmission codes too.

Learn More About OBD Error Code P0740

In this code, what is basically happening is that the Powertrain Control Module or PCM module has detected some unusual activity within the torque convertor clutch circuit of the vehicle. The Engine Control Module or ECM is capable of varying the torque converter clutch circuit application as per the requirement of the vehicle and its performance. In case the torque converter clutch application is malfunctioning and its noted that multiple times, the PCM module will trigger a ‘check engine’ light and set P0740 code.

 

What causes this problem with the Torque Converter Clutch Malfunction?

 

  • A malfunctioning torque converter clutch solenoid
  • Damages present of the torque converter or clutch
  • Wrong transmission fluid level
  • Skipping over of transmission maintenance
  • Any constraints within the transmission
  • Internal transmission damages present
  • An improper powertrain control module or transmission module

Replace/Repair These Parts To Fix OBD Code P0740

  1. Transmission Fluid - You may need to refill or replace the dirty transmission fuel. Don’t miss this part and go for the best quality transmission fuel for your vehicle.
  2. Torque Converter Clutch Solenoid - Simply repair or opt for replacement. At Parts Avatar we provide the best OEM car parts, and you will definitely find ones that are compatible to your vehicle. Order Online today!
  3. Torque Converter Clutch Solenoid Valve harness - Repair the harness, or replace it to get rid of P0740 error code.
  4. Transmission Valve Body - You may have to replace it, order online and avail free shipping on orders over CAD $99. This will help you resolve the P0740 error that’s flashing.
  5. Transmission Control Module - Try and repair the damages observed. If needed you can replace it with a new one by simply ordering online from Parts Avatar, we ship in just few days!

Symptoms Of OBD Error Code P0740

The symptoms exhibited by your vehicle will help you understand which of them are related to the OBD error code P0740. We at Parts Avatar, have listed few common symptoms you may be able to find and hence help you in the diagnosis of the error code.

 

Common Symptoms

 

  • The transmission showing issues with shifting in or out of a particular gear
  • The transmission may shift but in a rough manner
  • Vehicle is unable to move due to the torque converter clutch not engaging or disengaging
  • The engine may stall out
  • The transmission may overheat

How To Correct P0740 Torque Converter Clutch Circuit Malfunction

Here are some ways with which you can correct the P0740 code:

 

  • Replace the torque converter clutch solenoid
  • Replace the torque converter or clutch
  • Adding or replacing transmission fluid and its filter
  • Completely replacing the powertrain control module/ PCM
  • Repairing the current transmission
  • Replace the complete transmission with a new one

You can find all your replacements needs at one place at Parts Avatar. Order online, from the comfort of your home. We have a wide range of parts compatible for a large variety of cars. We ship across Canada, and accept bulk orders too!

Easy Diagnosis Of Engine Error OBD Code P0740

Diagnostics don’t have to be painful or confusing, hence we have laid down simple steps for diagnosis for you here:

 

  • Start by checking the transmission fluid and see if it’s in proper condition and at the optimum level required by your vehicle. If you notice any abnormality, then this could’ve been the issue. Accordingly resolve it by adding more or changing the transmission fluid.
  • Now check the transmission wiring harness for any damages or loose connections. For this you can take help from a factory wiring diagram and locate the appropriate power source and all the points of connections between the circuits. A fuse or relay may be powering the transmission and have gotten triggered by the TCM.
  • Now disconnect the harness of the transmission at the connector, power source as well as the TCM. Locate the appropriate positive and negative pins of the torque converter clutch solenoid to check for continuity inside the transmission internal wiring harness.
  • Now, use the DVOM (digital volt ohm meter) set it to ohms scale and check for the resistance in the circuit, by connecting the positive and negative leads to the appropriate pins. Observe the resistance reading. If it is too high and over limit (OL), then suspect a fault with the internal harness or the TCC solenoid. It will be necessary to remove the transmission oil pan for further diagnosis of the TCC solenoid
  • Use the DVOM again, set it to ohms, and test the wiring between the TCM and wiring harness connector at the transmission case. Observe for any short to ground, you can do this by moving the negative lead on the DVOM to any good ground known. Resistance should be high or even OL (over limit).
  • Now check the resistance at the TCC solenoid as well as the internal transmission wiring at the transmission case. Do this after removing the plug of the transmission harness.
  • Along with the TCC solenoid and internal harness, some vehicles use a transmission wire harness too as a single unit. Set your DVOM to ohms scale and connect the positive and negative leads on the pins for the TCC power and control circuit.
  • Now check for voltage on the power side circuit of the TCC solenoid. You can also do this at the wire harness connector at the TCM. Use a DVOM, but this time set it to volts scale. The positive lead should be at the wire that is to be tested and the negative lead to any known ground which is good. Keep the vehicle's engine off and key on, there should be presence of battery voltage.
  • It is mandatory to monitor the TCM with an advanced scan tool, since the torque converter clutch only gets activated during particular driving situations. This is to determine if the TCm is commanding the TCC solenoid and the feedback that is being read at the TCM. The vehicles TCC solenoid is typically in control by a duty cycle, which engages for a more comfortable torque converter clutch engagement.

Common Mistakes When Diagnosing the P0740 Code

 

  • Ignoring or overlooking common causes like dirty transmission fluid or misadjusted position sensor and proceeding with replacement of components that were working just fine.
  • Not following the diagnostic steps in order, or not completing them as needed for accurate diagnosis for OBD error P0740

Other Diagnostic Codes Related To OBD Code P0740

P0741 - Torque Converter Clutch Circuit Performance or Stuck Off

P0742 - Torque Converter Clutch Circuit Stock On

P0743 - Torque Converter Clutch Circuit Electrical

P0744 - Torque Converter Clutch Circuit Intermittent