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Error Code P2770 is defined as Torque Converter Clutch Circuit High, a problem with the wiring, computer, or with the solenoid itself.
The Torque Converter Lockup Clutch makes a strong connection between the engine and the transmission. When the Transmission Control Module (TCM) detects failure of the proper operation of the torque converter clutch, it will set code P2770.
This code means there’s an abnormality in the torque converter clutch circuit, which has been detected by the PCM (powertrain control module, also known as ECM or engine control module). The computer that controls automatic transmission uses a varying degree of torque converter clutch application (also known as torque converter lockup) to maximize the engine power and for better fuel efficiency.
Symptoms of this code vary from a failure of the torque converter clutch to disengage to no detectable symptoms at all. As with other error codes, it activates the Check Engine light and registers the code to the vehicle’s memory system.
Common symptoms include:
- Engine stalling when coming to a stop with the engine at idle
- Harsh shifting
- Transmission overheating
- Transmission slippage
- Decrease in fuel efficiency
This code can also be accompanied by other torque converter clutch, lock up or transmission slippage codes.
There are many possible causes for this code to appear, such as:
- Defective torque converter clutch pressure control solenoid
- Defective torque converter
- Hydraulic blockages in the transmission fluid passages
- Mechanical internal transmission failure
- Dirty or contaminated transmission fluid
- Low transmission fluid
- Defective TCM
- Defective PCM
How to Check
To diagnose this code, a code reader (scanner) and a digital volt/ohmmeter are necessary.
Insufficient fluid pressure is a common cause of this code, which usually results from low or dirty (contaminated) transmission fluid condition. To check, use a fluid dipstick to the transmission. Make sure that the level of transmission fluid within the specifications of the manufacturer.
Burned or abnormal fluids should be replaced. Remove the transmission pan for the presence of clutch and other materials and debris. This will also mean replacing the torque converter with a new one before the transmission can work properly, alongside with rebuild, fluid flush, and replacement of the transmission pan.
Then, inspect all internal connectors and wirings. Shorted or burned connectors and wires must be replaced.
In many cases, this will require replacement of full internal transmission harness if there are noted discrepancies.
If wirings and connectors are in good condition, connect the scanner to the diagnostic connector to record the freeze frame data when the code was set.
Clear the codes and then operate the vehicle to see if the code comes back. If the code doesn’t come back, that means you have an intermittent condition, which means you may have to wait for the problem to worsen a little to determine if it’s there.
If the transmission fluid is in good shape, but there is not enough of it, then add fluid so you can locate the leak and repair. Allow the vehicle to reach normal operating temperature for a test drive. This is so you can determine if the code comes back.
If the code doesn’t return, then the problem may be caused by transmission slippage caused by low fluid level or low-pressure condition.
If the code returns, however, and the transmission slips or causing delayed engagement, then check the pump pressure using a manual pressure gauge.
Use a hydraulic pressure diagram for your specific vehicle, thread the end of the gauge into the right opening on the transmission housing to record pump pressure.
Compare your results to the specifications set by the manufacturer, and repair accordingly.
If the code comes back, and the transmission seems to work properly, inspect the reference voltage and ground signals at the torque converter clutch pressure control solenoid.
If either of the reference voltage or ground circuits are open, check for continuity using a digital volt/ohmmeter, (disconnect all related control modules from the circuit before checking circuit resistance or controller damage may occur) and resistance in all circuits.
Repair or replace circuits or connectors as specified by the manufacturer. Use the wiring diagram from the manufacturer. Test all related circuits and the solenoid for resistance, then check the continuity and compare your findings with the specifications from the manufacturer.
Repair or replace damaged circuitry, connectors, or components.
Retest the system to ensure a successful repair.
Check the PCM, it may be rare for the PCM to be the cause of the problem, but it’s possible. When replacing the PCM, make sure you reprogram the PCM.
Replace solenoid (or solenoid pack) if the shift solenoid fails to manually activate, then retest the transmission control system.
How to Fix
Refill or changing of fluid transmission
Rebuild, fluid flush, and replacement of the transmission pan.
Replacement of torque converter
Replacement of full internal transmission harness
Repair leak in transmission pan
Repair hydraulic pressure as set by the manufacturer
Repair or replace system circuits/connectors
Replace and Reprogram PCM
In many cases, misdiagnosis is caused by overlooking the malfunctions in the torque converter clutch wiring, as people jump into replacing their control solenoid/torque converters.