Code Definition

P1127 — Throttle Control Actuator Power Source Circuit

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

About P1127

P1127 is a manufacturer-specific powertrain diagnostic trouble code recorded for Lexus vehicles. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P1127 is stored, the module has detected an electrical-circuit fault in the wiring, connector, or driver associated with the named component.

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.

P1127 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

On this Lexus electronic throttle control system the throttle control actuator, which includes the throttle motor and magnetic clutch, is supplied with battery voltage through a dedicated power source circuit controlled by the Engine Control Module (ECM). DTC P1127 sets when the ECM monitors this actuator power supply and finds the voltage missing, low, or out of range when it should be present. The fault usually points to the supply circuit, its fuse or relay, or the related wiring rather than the throttle motor itself. When the code is stored the ECM shuts down electronic throttle operation ...

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