P0C17: motor A resolver learning can fail without proving a bad position sensor

P0C17 is the motor A position-sensor not-learned diagnosis in the GM document. Its strategy concerns an unvalidated resolver offset without a previously valid stored value. A learning-status code is different from a direct resolver circuit-low or circuit-high fault.

Determine which learning condition failed

The source describes an incomplete learn when motor speed exceeds its permitted limit, filtered DC voltage is too low, or the required phase-current variation is insufficient for too much of the learning interval. It also describes a completed learn whose offset correction exceeds 30 degrees.

Those are different outcomes. A workshop should establish whether learning was interrupted by prerequisites or completed with an unacceptable result before deciding that a position sensor requires replacement.

Respect the controlled learning sequence

The table includes key-off and wakeup conditions, an initial low-speed requirement, a start delay and a 300 ms learning interval. These are controller-process details, not a complete relearn procedure for an owner to reproduce by cycling the key or forcing motor movement.

Preserve learning status, stored-value validity and related circuit faults. The source does not supply a universal scan-tool command or prove a particular mechanical alignment error. The correct vehicle service procedure must determine safe prerequisites and verification. Any physical motor or inverter work requires trained hybrid personnel and proper high-voltage isolation; clearing the code alone cannot create a valid learned offset.

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 291 · GM PDF, physical page 292.