Code Definition

P1790 — Transmission shift/timing solenoid fault

System: Powertrain  |  Type: Manufacturer-Specific  |  Make: Toyota

About P1790

P1790 is a manufacturer-specific 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.

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.

P1790 is a manufacturer-specific code. The same code string on a different make may have a different meaning. Always confirm the code's definition against the vehicle's service information for the specific make and model under test.

Code Information

This Toyota transmission uses shift timing solenoids that the Transmission Control Module commands to control the timing and pressure of gear changes, coordinating clutch and band apply for smooth shifts. The module commands the solenoid and monitors its circuit voltage and current draw, and judges performance by whether the resulting shift timing and feel match the command. DTC P1790 sets when the module detects an electrical fault on the shift timing solenoid circuit, such as an open, short, or abnormal current, or a performance fault where shifting is delayed, harsh, or does not follow the ...

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