P063C: Generator voltage-sense low input inside the ISG

P063C describes generator voltage-sense circuit A low. In Mazda's M Hybrid ISG, the monitor compares supply readings made by the main microcomputer and the stator-drive control electronics.

Understand the internal low signal

The page describes a disagreement of at least 5 V between the two supply measurements and an internal sensing input that is low. Its functional explanation identifies 0.1 V or less as the low-signal, short-to-ground condition. Detection uses a half-second period with the stator-drive circuit otherwise normal.

These are two different quantities: disagreement in measured supply voltage and the voltage of the internal sensing signal. The low signal should not be interpreted as a direct instruction to expect the external generator supply itself to be 0.1 V.

Recurrence supports the component conclusion

Mazda's procedure distinguishes a current event from a historical record, rechecks after an ignition transition and uses the original operating snapshot for verification. A displayed record potentially influenced by communication noise is considered separately from a repeatable internal failure.

Hybrid supply stops, vehicle loads depend on the 12-volt battery and i-stop, regeneration and assistance are inhibited. Continued operation can exhaust that battery. The source's unrelated P063B range wording is ambiguous and is not used here. Professional ISG diagnosis should confirm the low-input branch and current status without improvising internal power-electronics tests.

Documented application

Mazda3 workshop manual 01/2019 onward, d9n1-1a-22d_ver10; INTEGRATED STARTER GENERATOR (ISG). Verify exact vehicle specification; this is a Mazda application example. Mazda factory diagnostic page, mirrored by CHARM.