Guide To P0743 OBD Error Code Solutions

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The job of your vehicles Torque converter clutch or TCC is to establish the “mechanical lock” between the transmission and the engine. It does so, by increasing the make 1:1 rotation per minute or RPM ratio between the Transmission Input Shaft and the Torque Converter rotational speed. This is important to eliminate the loss of power that may happen with the fluid and/or hydraulic lock in the conventional Torque Converter. Also, when the engine is running on low speed the emission output as well as the overall fuel consumption both are low.

This transfer of power results in excessive heat, which kills transmission. The lockup torque converter ensures the transmission is more efficient at highway speed and controls the heat too. It is the TCC that locks up the converter. When the OBD error P0743 is set, it’s typically because the PCM is reading higher than 200 RPM difference between the rotational speed torque converter and the transmission input shaft. This is not good, because the ratio between the converter RPM and input RPM must be 1:1 when the torque converter lockup clutch engages.

What causes this problem with the Torque Converter Clutch Circuit Electrical?

• Defect of the Torque Converter Lockup Solenoid
• Defect of the Engine Coolant Temperature Sensor
• Defect of the Torque Converter Clutch
• Defect in the transmission control Valve Body
• Failure of TCC assembly in the torque converter
• Contaminated transmission fluid restricting the hydraulic passages
• Transmission fluid is low or dirty

1. Engine Coolant Temperature Sensor - You can opt for repairs if needed proceed with replacing it with the best from Parts Avatar. We ship all across Canada.
2. Transmission Fluid - Transmission oil change will be mandatory when it is dirty or low. Check if the error P0743 still sets after clearing the codes.
3. Torque Converter Clutch Solenoid - As per diagnosis you try repairing or opt for replacement. We at Parts Avatar offer free shipping on orders over CAD $99. Order now and remove the stress of P0743 error code today!
4. Torque Converter Clutch Solenoid Valve harness - Repair the harness or replace with Parts Avatar online as per need. Track your shipment and have it delivered to your doorstep.
5. Transmission Valve Body - You mechanic will guide you with feasibility of repairs, it’s best to change parts when they’re damaged. You can order online at Parts Avatar easily and get the best quality parts.
6. Transmission Control Module - If repairing isn’t an option, replace easily from Parts Avatar. We have a wide range of OEM parts on our website, that are compatible with your specific vehicle. Order online today.

It is vital to know the symptoms of an issue as only then you would be able to solve the problem. So that’s why we have listed out some major symptoms of OBD Code P0743 here:

Common Symptoms

• Illuminated malfunction Indicator Lamp illuminated
• Negligible fall in fuel economy, not affecting engine performance
• Transmission doesn’t shift in or out of a particular gear
• The Transmission may shift but harshly
• Engine may stalling becomes more common
• The transmission shows signs of becoming overheated

Have a look at some ways with which you can correct the P0743 code:

• Torque converter to be totally rebuild, fluid flushed or replaced
• Repair or replace shorted or burned wires
• Replace full internal transmission harness if there are issues
• Refill the transmission with the right fluid to the right quantity as needed by vehicle
• Replace the pump
• Repair or replace system circuitry, connectors, and/or components
• After repairs/ replacements of system circuits/connectors ensure to retest the system to check successful repairs.
• Replacing PCM (very rare)

There is no need to get strained if your OBD Code is still flashing up as we are here at your service. Have a look at our superior variety of Transmission Fluid, Engine Coolant Temperature Sensor, Torque Converter Clutch Solenoid, Torque Converter Clutch Solenoid Valve harness, Valve Body, Transmission Control Module and many more. Now all your problems would vanish within no time.

It is essential to diagnose this fault code. Here are some steps which a mechanic should follow for diagnosing the problem that triggered a P0743 code to be stored:

• Get hold of a diagnostic scanner for your vehicle and also a digital volt/ohm meter (DVOM). These are very important in diagnosing error codes.
• If you have noticed that the transmission pressure isn't as per requirement in-order to actuate the gear changes, this code will be set. Check to see if the fluid is low or dirty, fill or change it accordingly. Insufficient or dirty transmission oil can cause low fluid pressure. You can begin transmission diagnosis by inspecting the transmission fluid dipstick if needed. Ensure the fluid level is as per manufacturer's prescribed limit.
• Any unusual smell of the fluid should be checked, burned fluid is a sign that the transmission was running on low levels of transmission oil. Fluid that is not clean should be considered in adequate and replaced immediately. Do not add fresh fluid to the contaminated one. If your vehicle is running on burned transmission fluid, then it may have also caused internal mechanical damage. Check for that too and resolve matter.
• If it smells burned, remove the transmission pan and check for any debris or clutch material that may be present.
• Now proceed to investigating any burned or shorted wires, accordingly replace circuitry and connectors. You may require replacement of the full internal transmission harness, if the problems are extensive.
• Upon investigation, if you found that all the wiring, connectors and components are normal, then it’s time to connect the diagnostic scanner and retrieve all the trouble codes stored and freeze frame data. Clear all codes after making note of them. And take your vehicle on a test drive.
• If the PCM enters readiness mode, then it will mean that you have an intermittent condition. These are difficult to diagnose and, in most cases, require the issue to worsen before corrective measures can be taken.
• Compare your vehicles problematic symptoms with the manufacturer's specifications and accordingly make amends.
• Low pump pressure is usually caused by clogged hydraulic passages, defect in the pump, faults in shift solenoids or even faulty electronic pressure regulator. For pump replacement you will have to remove transmission and also perform partial disassembly.
• If the code has immediately rest and the transmission has been operating normally, you will have to check for reference voltage and ground signals at the torque converter clutch lock up solenoid. If they are open are shorted use the DVOM to check continuity and resistance in all of the circuits. In order to check continuity, you will have to start off by disconnecting all the related control modules, only after doing this should you check resistance as skipping this can cause controller damage.
• Now as needed, proceed with repairing or replacing the connectors, circuitry, and/or components, which aren’t meeting the specifications prescribed by the manufacturer.
• Remember to retest the system for ensuring success in repairs.
• If you have found that all the system circuits are in fact intact then connect the scanner to the diagnostic connector and try to manually activate the torque converter clutch lock up solenoid.
• A failed PCM is very rare for this OBD error, so don’t jump to conclusions. Replacement of PCM is expensive and requires reprogramming as well.
• Upon trying if the shift solenoid still fails to activate manually, you will have to replace the solenoid or the solenoid pack. After doing that, retest the transmission control system one last time.

Common Mistakes while diagnosing P0743 error

Unwarranted replacement of the lock up solenoids and torque converters, when the problem is with malfunctioning wires affecting the torque converter.