What Does the P0740 Code Mean?
The P0740 code indicates that the powertrain control module (PCM) has observed an unusual behaviour within the torque converter clutch circuit. Every vehicle built since 1996 returns this generic trouble code when a problem is detected with the torque converter clutch circuit, however, modern vehicles now determine when to give this code based on other information as well such as throttle position, engine load, car speed etc.
|P0740 Trouble Code||Check engine light illuminates |
Drop in Fuel Economy
Torque Converter Clutch fails to engage
Trouble when shifting Gears
Transmission gets stuck in a single gear
Car fails to move when in gear
|Damaged Torque Converter Lockup Solenoid|
Defective Torque Converter or Clutch
Internal Damage within the Transmission
Faulty Valve Body
Low Transmission Fluid Level
|Repair and replace the Torque Converter Clutch solenoid |
Replace Torque Converter Clutch
Check and replace transmission fluid
Repair powertrain control module
Replace the transmission system
Initially, you won’t notice any symptoms if any problem occurs with the torque converter clutch. However, if the problem persists and is ignored for a long time, your torque converter clutch can fail totally and disrupt the engine performance as well. Common symptoms include:
- Check engine light illuminates
- Drop in Fuel Economy
- Torque Converter Clutch fails to engage
- Trouble when shifting Gears
- Transmission overheating
- Engine Stalling
- Transmission gets stuck in a single gear
- Car fails to move when in gear
- Engine misfire
The P0740 trouble code can be triggered due to many reasons. The most common causes include:
- Damaged Torque Converter Lockup Solenoid
- Defective Torque Converter or Clutch
- Internal Damage within the Transmission
- Faulty Valve Body
- Low Transmission Fluid Level
- Non-functioning Engine Coolant Temperature Sensor
- Damaged Wiring
The first step should be to check the wiring and connection of the torque converter clutch leading to the PCM. Most of the time, the issue is only with the wiring and bad connection while the mechanics will rip you off your money by stating a huge problem. If the problem is not with the wiring, check for the following possible solutions:
- Repair and replace the Torque Converter Clutch Solenoid
- Replace Torque Converter Clutch
- Check and replace transmission fluid
- Repair powertrain control module
- Replace the transmission system
How to Diagnose the P0740 Code?
The P0740 code can be a little difficult to diagnose initially but is observable when the car experiences drivability issues. You would need a factory wiring diagram of your car to locate the right connections points between the circuit and notice for damage with the wiring. Moreover, you should also check the transmission fluid.
Here are some steps you should follow to diagnose the P0740 code.
Connect a Car Battery Charger
It is important that your vehicle’s battery does not drain while working on troubleshooting the trouble codes. Which is why it is important that you attach a car battery charger whenever you are working on the car with the ignition on. Moreover, the low battery may also generate additional trouble codes which will make the situation even more confusing.
Connect the OBD2 Scanner
To read information generated by the trouble codes, it is necessary to have the Obd2 Code Scanner. This device lets you easily read the data from the trouble code and also has built-in values that allow you to make a comparison and determine the cause of the problem. You’ll also need a digital volt ohm-meter to test the circuit resistance.
Check for Wire Connection
The most important and initial step is to determine if any bad connection or wiring is causing the P0740 trouble code to generate. Inspect the wiring leading to the transmission system and notice for signs of damage. You can refer to the vehicle factory wiring diagram to easily identify all connection points.
Check Transmission Fluid
If you have checked the wiring and connections leading to the transmission system and everything seems to be in order, check the transmission fluid to see its proper level and condition. If the fluid seems less or different, it may be a part of the problem.
Check Resistance of TCC Solenoid
Start by removing the harness plug of the transmission system and then using the DVOM, check the resistance of the TCC solenoid. If the resistance reading comes too high then there is possibly something wrong with the solenoid.
The TCM can be monitored using an advanced diagnostic tool and it requires certain expertise to understand the reading. It is advisable to take your car to an auto specialist who will conduct this test and let you know if the problem is with the TCM.
Recommended Tools to Fix P0740 Code
Transmission Torque Converter Clutch Solenoid Replacement
In most of the cars, the transmission solenoid is located inside the oil pan and is connected to valve body. In such a case, an auto expert will easily replace the damaged shift solenoid. However, in some cars, the transmission solenoid is packed in multiple units and if a problem occurs, the whole pack needs to be replaced. The average cost to replace a single transmission solenoid comes between $20 and $100. A whole pack may cost around $200. The labor cost comes approximately $150 to $400.
Does the P0740 Code Need Serious Attention?
The engine is not the only thing that drives the vehicle. The transmission system is equally important and any problem with the transmission system can leave you stranded in the middle of the road. If you notice early symptoms of the P0740 code, it is a good idea to follow the guide above and diagnose the issue or take your car to an auto specialist. If the code continues to persist and is not taken care of, the transmission system can fail and may cause damage to the engine as well. This is why the P0740 code should be dealt with as quickly as possible.
How to Avoid the P0740 Code?
If the P0740 code is ignored for long, it can result in serious drivability issues and may damage other components besides the transmission. You can avoid this problem by regularly (or at regular intervals) checking and replacing the transmission fluid and the filter. This ensures that the components inside the transmission system stays well lubricated and work with maximum efficiency.
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