The P0740 code can be very serious as it can cause drivability issues. This is one of the codes that can leave a driver stranded on the side of the road. A good running engine means nothing without a properly operating transmission to transfer the engine power to the wheels. It is a good idea to have this issue diagnosed and repaired as soon as possible. But driving with this code can be dangerous. So follow the article to know how to fix p0740 code.
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What Does The P0740 Code Mean?
P0740 code means is that the powertrain control module (PCM) has detected something unusual within the torque converter clutch circuit. The powertrain control module can vary the application of the torque converter clutch for optimal vehicle performance. If the torque converter clutch application is abnormal (usually multiple times) the powertrain control module will trigger a Check Engine Light.
What Are the Causes Of The P0740 Code?
Some potential causes of the P0740 code may include:
- A faulty torque converter clutch solenoid
- A damaged torque converter or clutch
- Incorrect transmission fluid level
- Skipping over transmission maintenance
- A restriction within the transmission
- Internal transmission damage
- A faulty powertrain control module or transmission module
What Are The Common Symptoms Of The P0740 Code?
A P0740 code should always be addressed immediately to prevent further damage to the vehicle. It may be unsafe to drive if this trouble code is accompanied by drivability symptoms.
If you experience any of the signs below, make sure to address the issue right away.
1. Check Engine Light Illuminates
A wide variety of problems can trigger the check engine warning light including an issue with the Torque converter clutch circuit or related components.
2. Shifting Problems
Your transmission may exhibit problems, such as slippage, harsh shifting, and a limited gear range.
3. Engine Stalling
If the Torque converter clutch circuit is stuck on, it may cause the vehicle to stall when coming to a stop.
4. Shudder Felt Throughout The Vehicle
A Torque converter clutch circuit that is not engaging or disengaging properly can cause a shudder that’s felt at certain speeds.
5. Reduced Fuel Economy
Failing to engage the torque converter clutch results in slippage that reduces fuel mileage.
6. Increase In Engine Speed
A Torque converter clutch circuit that is not engaging can cause a slight increase in engine RPMs.
How To Fix P0740 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 Torque converter circuit solenoid from working properly. The wiring and connectors should also be inspected for damage and corrosion. In case no issues were found by this stage, then the torque converter and Torque converter circuit solenoid will have to test.
1. Wiring Harness
See in case 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 Transmission Control Module, power, and transmission connector, disconnect the transmission harness. By finding the right positive and negative pins of the Torque converter circuit 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 fault the torque converter clutch solenoid. Or otherwise, the internal harness if you get an over the limit or extremely high resistance. This is the first way how to fix p0740 code.
2. 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. In case you get a reading that is OL or very high remove the transmission oil pan.
3. 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.
What Kind Of Repairs Will Fix The P0740 Code?
Several repairs could potentially address the P0740 trouble code of how to fix p0740 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
Can You Drive With A Bad TCC Solenoid?
Yes, you can usually drive a car with a bad shift solenoid. Granted, it might not shift past a particular gear, but you should be able to drive it for a short period of time without causing any serious damage.
How Much Does It Cost To Repair The P0740 Code?
It is important for the safety of the driver to properly diagnose and repair problems associated with the P0740 code as soon as possible. If left untreated, the engine in the vehicle could stall and cause serious drivability issues.
Applying the proper diagnosis and repairs can prevent a driver from being stuck on the side of the road with an inoperable vehicle. Hiring a professional mechanic is a great way to ensure that each process will be completed correctly and efficiently.