P0740: Torque Converter Clutch Circuit Malfunction OBD-II Trouble Code

The presence of a P0740 DTC means that the ECU has detected a problem in the circuit that controls the torque convertor clutch solenoid. A torque converter clutch (TCC) circuit malfunction is what triggers trouble code P0740. All vehicles manufactured since 1996, regardless of make and model, may return this generic trouble code. Yet, different models may have varying steps for repairs and diagnosis. Below, we will get you started on remedying this issue. The transmission control module (TCM) controls the torque converter clutch (TCC). When disengaged, the TCC locks the converter shell to the turbine shaft – creating a 1 to 1 connection between the transmission and engine to prevent slippage. If the application of the clutch is abnormal (multiple times), then trouble code P0470 appears.

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How Serious is the Code?

A P0740 diagnostic trouble code means that the ECU isn’t in complete control of the torque convertor, so drivability issues are sure to follow. Situated between the transmission and the engine, the torque converter works to equalize the speed by multiplying the torque in order to optimize vehicle performance (increases fuel efficiency and reduces the transmission fluid temperature.

Symptoms

Symptoms of a P0740 include:

  • Check engine light
  • Delayed, harsh or erratic shifts
  • Engine stalling
  • Transmission shudders/shakes when coming to a stop or accelerating
  • Getting ‘stuck’ in a gear
  • Vehicle won’t move when in gear
  • Decreased fuel economy
  • Overheated transmission

Causes

  • Low transmission fluid level
  • Dirty transmission fluid / filter
  • Damaged wiring/connector
  • Faulty torque convertor clutch solenoid / TCC solenoid
  • Faulty torque convertor and/or clutch assembly
  • Internal pressure issue
  • Valve body issue
  • TCM failure

How to Diagnose the Code?

To determine what is causing this DTC, a mechanic should first assess the condition of the transmission fluid, as dirty ATF can keep the TCC solenoid from working properly. The wiring and connectors should also be inspected for damage and corrosion. If no issues were found by this stage, then the torque convertor and TCC solenoid will have to be tested.

Wiring Harness

See if there are loose connections or damage in the wiring harness of the transmission. Find all connections between circuits and the appropriate power source by using the factory wiring diagram. A relay or fuse may power the transmission, and the transmission control module may trigger it.

At the TCM, power, and transmission connector, disconnect the transmission harness. By finding the right “+” and “-“ pins of the TCC solenoid, check for transmission internal wiring harness continuity.

Set a digital multimeter to the ohms scale to check the circuit resistance with the negative and positive leads connected to the right pins. You probably have a fault in the torque converter clutch solenoid or the internal harness if you get an over limit or extremely high resistance.

TCC Solenoid

After removing the transmission harness plug, check the wiring in the case of the transmission and the torque converter clutch solenoid resistances. Depending on the make and model of your vehicle, the internal harness and solenoid may be one unit.

Place the negative and positive leads of your multimeter (set to the ohms scale) on the appropriate pins of the control circuit and TCC power. The resistance should be within the specifications set out by the manufacturer. If possible, inspect the TCC solenoid inside the transmission by removing the transmission oil pan if you get a reading that is OL or very high.

Transmission Control Module (TCM)

To determine what the actual feedback is at the TCM and if it is commanding the solenoid, you need to track the TCM using a scan tool since the TCC is only activated under specific driving conditions. To get a comfortable TCC engagement, the solenoid is controlled by the duty cycle normally.

Digital storage oscilloscopes or graphing multimeters set to the duty cycle will be needed to test if a signal is actually being sent by the TCM. The negative is probed to a good ground and the positive to the wiring harness that is plugged into the TCM. The TCM may be at fault when the cycle is intermittent or at 0 percent or 100 percent.

Common Mistakes When Diagnosing

The most common mistakes made when diagnosing P0740 is thinking that the problem is related to driveline issues, internal transmission issues, or engine misfire issues. It’s not uncommon to assume that the torque convertor itself needs to be replaced/rebuilt, when it could just be a faulty TCC solenoid or dirty/contaminated transmission fluid.

What Repairs Will Fix the P0740 Code?

There are several repairs that could potentially address the P0740 trouble code, including:

  • Installing a brand new transmission
  • Perform an overhaul of the transmission
  • Powertrain control module replacement
  • Replacing or adding transmission filter and fluid
  • Replacing the clutch or torque converter
  • Torque converter clutch solenoid replacement

Related Codes

P0741 – Torque Converter Clutch Circuit Performance or Stuck Off

P0742 – Torque Converter Clutch Circuit Stuck On

P0743 – Torque Converter Clutch Circuit Electrical

P0744 – Torque Converter Clutch Circuit Intermittent

P2769 – Torque Converter Clutch Circuit Low

P2770 – Torque Converter Clutch Circuit High

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Fair Remanufactured Transmission Price Ranges by Transmission Model Updated July 2018

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Links To Diagnostic Codes

Trouble CodeDescription
P0218Transmission Over Temperature Condition
P0700Transmission Control System (MIL Request)
P0701Transmission Control System Range/Performance
P0702Transmission Control System Electrical
P0703Torque Converter/Brake Switch B Circuit
P0704Clutch Switch In put Circuit Malfunction
P0705Transmission Range Sensor Circuit Malfunction (PRNDL Input)
P0706Transmission Range Sensor Circuit Range/Performance
P0707Transmission Range Sensor Circuit Low Input
P0708Transmission Range Sensor Circuit High Input
P0709Transmission Range Sensor Circuit intermittent
P0710Transmission Fluid Temperature Sensor Circuit
P0711Transmission Fluid Temperature Sensor Circuit Range/Performance
P0712Transmission Fluid Temperature Sensor Circuit Low Input
P0713Transmission Fluid Temperature Sensor Circuit High Input
P0714Transmission Fluid Temperature Sensor Circuit Intermittent P0715
P0715Input/Turbine Speed Sensor Circuit
P0716Input/Turbine Speed Sensor Circuit Range/Performance 
P0717Input/Turbine Speed Sensor Circuit No Signal
P0718Input/Turbine Speed Sensor Circuit Intermittent
P0719Torque Converter/Brake Switch B Circuit Low
P0720Output Speed Sensor Circuit
P0721Output Speed Sensor Circuit Range/Performance
P0722Output Speed Sensor Circuit No Signal
P0723Output Speed Sensor Circuit Intermittent
P0724 Torque Converter/Brake Switch B Circuit High
P0725Engine Speed Input Circuit
P0726Engine Speed Input Circuit Range/Performance
P0727Engine Speed Input Circuit No Signal
P0728Engine Speed Input Circuit Intermittent
P0729Gear 6 Incorrect Ratio
P0730Incorrect Gear Ratio
P0731Gear 1 Incorrect Ratio
P0732Gear 2 Incorrect Ratio
P0733Gear 3 Incorrect Ratio
P0734Gear 4 Incorrect Ratio
P0735Gear 5 Incorrect Ratio
P0736Reverse Incorrect Ratio
P0738TCM Engine Speed Output Circuit
P0739TCM Engine Speed Output Circuit Low
P0740Torque Converter Clutch Circuit Malfunction
P0741Torque Converter Clutch Circuit
P0742Torque Converter Clutch Circuit Stuck On
P0743Torque Converter Clutch Circuit Electrical
P0744Torque Converter Clutch Circuit Intermittent
P0745Pressure Control Solenoid 'A'
P0746Pressure Control Solenoid 'A' Performance or Stuck Off
P0747Pressure Control Solenoid 'A' Stuck On
P0748Pressure Control Solenoid 'A' Electrical
P0749Pressure Control Solenoid 'A' Intermittent
P0750Shift Solenoid 'A'
P0751Shift Solenoid 'A' Performance or Stuck Off
P0752Shift Solenoid 'A' Stuck On
P0753Shift Solenoid 'A' Electrical
P0754Shift Solenoid 'A' Intermittent
P0755Shift Solenoid 'B'
P0756Shift Solenoid 'B' Performance or Stuck Off
P0757Shift Solenoid 'B' Stuck On
P0758Shift Solenoid 'B' Electrical
P0759Shift Solenoid 'B' Intermittent
P0760Shift Solenoid 'C'
P0761Shift Solenoid 'C' Performance or Stuck Off
P0762Shift Solenoid 'C' Stuck On
P0763Shift Solenoid 'C' Electrical
P0764Shift Solenoid 'C' Intermittent
P0765Shift Solenoid 'D'
P0766Shift Solenoid 'D' Performance or Stuck Off
P0767Shift Solenoid 'D' Stuck On
P0768Shift Solenoid 'D' Electrical
P0769Shift Solenoid 'D' Intermittent
P0770Shift Solenoid 'E'
P0771Shift Solenoid 'E' Performance or Stuck Off
P0772Shift Solenoid 'E' Stuck On
P0773Shift Solenoid 'E' Electrical
P0774Shift Solenoid 'E' Intermittent
P0775Pressure Control Solenoid 'B'
P0776Pressure Control Solenoid 'B' Performance or Stuck Off
P0777Pressure Control Solenoid 'B' Stuck On
P0778Pressure Control Solenoid 'B' Electrical
P0779Pressure Control Solenoid 'B' Intermittent
P0780Shift Malfunction
P07811-2 Shift
P07822-3 Shift
P07833-4 Shift
P07844-5 Shift
P0785Shift/Timing Solenoid
P0786Shift/Timing Solenoid Range/Performance
P0787Shift/Timing Solenoid Low
P0788Shift/Timing Solenoid High
P0789Shift/Timing Solenoid Intermittent
P0790Normal/Performance Switch Circuit
P0791Intermediate Shaft Speed Sensor Circuit
P0792Intermediate Shaft Speed Sensor Circuit Range/Performance
P0793Intermediate Shaft Speed Sensor Circuit No Signal
P0794Intermediate Shaft Speed Sensor Circuit Intermittent
P0795Pressure Control Solenoid 'C'
P0796Pressure Control Solenoid 'C' Performance or Stuck off
P0797Pressure Control Solenoid 'C' Stuck On
P0798Pressure Control Solenoid 'C' Electrical
P0799Pressure Control Solenoid 'C' Intermittent

Links To Symptoms

Symptoms
Low Transmission Fluid
Transmission Slipping
Limp Mode
Burnt Transmission Fluid
DTC / Check Engine Codes
Lack of Responses
Torque Converter Problems
Whining, Clunking or Humming
Transmission Fluid Leak
Solenoid Problems

Comments

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1 thought on “P0740: Torque Converter Clutch Circuit Malfunction OBD-II Trouble Code

  1. I have a 96 xhevy caprice classic with a 4.3 engine. Recently did tune up which include transmission seal, filter and changed fluid. Its still leaking and now it wont shift into any gear and the fluid has turned brown and sluggish. Car only has 107k miles

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