Code Definition

P077D — Output Speed Sensor Circuit High

System: Powertrain  |  Type: Generic (OBD-II Standard)  |  Make: Toyota

About P077D

P077D is a generic (obd-ii standard) powertrain diagnostic trouble code recorded for Toyota vehicles. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P077D is stored, the module has detected a signal or supply voltage higher than the expected operating range; and a sensor-related fault — the reported value from the named sensor is out of spec.

Scanning & clearing: A generic OBD-II scan tool will usually read and clear powertrain (P) codes. For live data, freeze-frame capture, and bi-directional tests you may need a more capable scan tool that supports the vehicle's ECM protocol.

Because P077D is a generic OBD-II code, its base definition is shared across manufacturers. The specific diagnostic steps, reference values, and repair procedures can vary by vehicle, and the TaT Diagnostic Assistant includes verified procedures submitted by working technicians.

Code Information

The output speed sensor reports the rotational speed of the transmission output shaft, giving the control module its reference for road speed, gear ratio verification, shift scheduling, and torque converter lockup timing. Most applications use a variable reluctance sensor that generates its own alternating current signal from a toothed rotor, while others use a hall effect sensor supplied with a reference voltage that returns a square wave. DTC P077D sets when the module detects the signal circuit sitting at an abnormally high voltage, which typically means the circuit is open, is shorted to b...

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