P1740 Code failures by brands


Description of DTC code P1740

The TCC (Torque Converter Clutch) sets a 1-to-1 linking between the transmission and the vehicle engine, which rises fuel mileage and makes a reduction of the transmission fluid temperatures. Slippage takes a lot of energy during the engagement phase. By locking the converter housing to the turbine shaft, slippage is prevented. The clutch controls a solenoid in the same system, when it is closed, the TCC remains active as the car slows to a stop. This resistance causes the engine to stumble and eventually stop.

The clutch is installed inside the torque converter housing. It contains a friction material whose function is to lock the turbine shaft to the inside of the converter housing. The Transmission Control Module provides a pulsing voltage to the TCC solenoid, and in response, this makes a valve move and sends pressurized fluid into the clutch circuit, thus engaging the TCC. When the clutch is disengaged, the converter allows the engine to turn without stalling.

When the Powertrain Control Module (PCM) asks for the TCC activation during 3rd gear and overdrive, self-tests are carried out on the clutch and Overdrive Solenoid. In case it is not accomplished the expected RPM drop when attempting to engage the TCC/Overdrive, the P1740 OBD2 diagnostic code will be set because there can be a malfunction.

Symptoms of fault code P1740

  • Check Engine Lamp illuminated.
  • Delays during gear changes.
  • The fail-safe mode is activated.

Causes of OBD2 P1740

The P1740 OBDII fault code is set for one of the following reasons:

  • The transmission may not have the required fluid level.
  • Transmission fluid may have contamination levels.
  • TCC cables or connectors may be in poor condition.
  • The Overdrive Solenoid harness may be damaged.
  • The Torque Converter Clutch (TCC) or Overdrive Solenoid (OD) may be faulty.

Possible solutions of the DTC code P1740

Steps to troubleshoot the P1740 OBD2 DTC:

  • Verify that the available amount of transmission fluid is at the optimum level to ensure good system performance. Likewise, check that the transmission fluid is not contaminated. Make any necessary corrections.
  • Inspect the condition of the TCC and Overdrive Solenoid wires and connectors. If you discover poor condition due to common deficiencies, make appropriate repairs or replacements.
  • Check the Torque Converter Clutch electrical connections for damage. Measure the voltages of this circuit, as well as the solenoid. If discrepancies are discovered, make the necessary corrections.

Codes related to P1740

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