P0C05: motor A missing-current detection depends on rotor position

P0C05 is the motor A U-V-W circuit/open monitor in this GM document. Its strategy looks for missing motor current as the rotor moves through the relevant phase-axis region. The generic open-circuit title does not mean the controller has physically located a broken wire.

The sequence is more specific than low current

The row first requires both non-peak phase sensors above the stated 9 A magnitude, then looks for phase-axis current below that magnitude. Rotor position must be within the published window around the phase axis. This sequence is different from a current-sensor electrical-range fault measured with PWM disabled.

The inverter must be in RUN, inverter voltage must exceed 35 V, and peak phase current must meet the stated minimum. These prerequisites explain why a stationary or lightly observed system may not perform the same missing-current evaluation.

Preserve phase and position evidence together

The useful record combines phase-current response, rotor-position context and controller state. One low phase value without the rest of the sequence does not demonstrate the complete monitor criterion, and the code alone does not identify the physical cause.

GM supplies internal timing and count information, not a procedure for manually spinning or energizing the motor. A trained hybrid technician must use the exact vehicle's circuit and safety instructions for diagnosis. Physical inverter or motor access requires proper high-voltage isolation, followed by verification under the applicable controlled service procedure.

Source and applicability

GM 2010 10OBDG10 Hybrid Diagnostics, cited BPCM or hybrid-controller monitor only. Historical calibration values are not universal specifications; no per-code model, engine or hardware fitment has been established. GM PDF, physical page 284.