P2770 Torque Converter Clutch Circuit High Trouble Code

P2770 Torque Converter Clutch Circuit High

OBD-II Trouble Code Technical Description

Torque Converter Clutch Circuit High

This diagnostic trouble code (DTC) is a generic OBD-II powertrain code. It is considered generic because it applies to all makes and models of vehicles (1996-newer), although specific repair steps may vary depending on the model.

What does that mean?

Modern vehicles equipped with automatic transmissions / transaxles use a torque converter between the engine and transmission to increase the engine torque output and drive the rear wheels.

 

The engine and transmission are actually connected by a fluid coupling mechanism inside of the torque converter which is what multiplies the torque until the speeds equalize and create a "stall" speed where the difference in actual engine RPM and transmission input RPM is around 90% efficient. Torque converter clutch (TCC) solenoids commanded by the Powertrain control module/Engine control module (PCM/ECM) or the Transmission control module (TCM) to direct hydraulic fluid and engage the torque converter clutch to create a solid coupling and increase efficiency.

The transmission control module has detected a fault with the circuit that operates the torque converter clutch solenoid. We will consider the TCM the controller for the sake of this article although it may be controlled through the PCM/ECM, consult factory wiring diagrams to determine which system is being used.

Note: This code is similar to codes P0740, P0741, P0742, P0743, P0744, and P2769.

A P2770 code means that the PCM has detected that the TCC electrical circuit is experiencing a high condition. There may be other diagnostic trouble codes associated with the transmission control module that can only be accessed by using an advanced scan tool. If any additional transmission related DTC's appear in addition to the P2770, an electrical failure is likely.

Symptoms

Symptoms of a P2770 trouble code may include:

Malfunction Indicator Lamp (MIL) illuminated (a.k.a. Check Engine Light) Minimal decrease in fuel economy, this will not affect engine performance

Potential Causes

Causes of this DTC may include:

Wiring harness to transmission damaged, loose connection, open or shorted circuit Torque converter clutch (TCC) solenoid Transmission control module (TCM)

Diagnostic Steps for P2770 DTC

Wiring harness - Check transmission wiring harness for damage or loose connections. Use a factory wiring diagram to locate the appropriate power source and all connection points between circuits. The transmission may be powered by a fuse or relay, and triggered by the TCM. Disconnect the transmission harness at the transmission connector, power source and TCM. Check for continuity inside the transmission internal wiring harness by locating the appropriate + and - pins for the torque converter clutch solenoid.

Using a digital volt ohm meter (DVOM), set to ohms scale, check for resistance in the circuit with the positive and negative leads on the appropriate pins. If resistance is extremely high or over limit (OL), suspect a fault with the internal harness or the TCC solenoid - removing the transmission oil pan may be necessary to further diagnose the TCC solenoid.

Test the wiring between the TCM and the wiring harness connector at the transmission case using the DVOM set to ohms. Check for a possible short to ground by moving the negative lead on the DVOM to a known good ground, resistance should be very high or over limit (OL).

Torque converter clutch (TCC) solenoid - Check the resistance in the TCC solenoid and internal transmission wiring at the transmission case after removing the transmission harness plug (if applicable, some makes/models use a TCM bolted directly to the transmission case). Some makes/models use a transmission wir

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