P0C52: motor A resolver circuit A low concerns the S13 reference

P0C52 is motor A position-sensor circuit A low in the GM source. The row identifies the monitored quantity as the resolver S13 circuit reference voltage. This is more specific than a general claim that the motor's angular position is incorrect.

Follow the reference-voltage branch

The documented low threshold is below 0.5 V with the wakeup signal on. GM uses fifty qualifying counts among eighty at a 10.4 ms rate and lists one-trip reporting. The companion high-range code uses a different threshold and a shorter count filter.

That difference matters when reviewing intermittent behavior. One brief low sample or the timing of a high fault should not be treated as identical evidence for the low-range monitor.

Separate circuit evidence from learned position

The same manual has distinct resolver learning and signal-performance diagnoses. A low reference-voltage fault does not, by itself, establish that a learned offset is wrong or that the motor requires mechanical adjustment. Preserve related codes and the S13 reference report to guide the correct diagnostic branch.

The source provides no universal connector pin, safe probing method or mandatory resolver replacement. S13 must be mapped through the actual vehicle's circuit information. A qualified hybrid technician must establish high-voltage isolation for physical work and verify a credible reference signal during eligible operation. Clearing the code is not a substitute for demonstrating that the low condition has been resolved.

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 292.