P06D3: Reference E low identifies the VSS2 speed-sensor supply

P06D3 is the low code for sensor reference voltage E. In this GM TCM implementation it applies to speed-sensor supply VSS2, not to one of the five-volt reference rails. That implementation detail changes the voltage boundary that should be interpreted.

The second speed-sensor supply is below range

The listed boundary is VSS2 below 8 volts, with 250 millivolts of hysteresis and a confirmation period of at least 75 milliseconds. The check runs continuously while main battery voltage is above 8.75 and below 18 volts.

Cranking and the STOP key state are excluded. P0882 and P0883 disable the assessment, so a low-main-supply event cannot be treated as an ordinary completed VSS2 monitor without considering those exclusions.

Identify the rail before the connected sensor

Preserve the VSS2 supply reading and the relevant speed-sensor fault context. A normal VSS1 reading is not verification of VSS2, and a speed-value error by itself does not show that the eight-volt boundary was crossed.

The source does not identify every device on the rail or prove which one caused the low condition. Localization requires the actual transmission’s supply distribution and service circuit procedure. Do not substitute a generic five-volt-reference test or infer a sensor location from the letter E. A meaningful repair check concerns the correct rail while its monitor is enabled and able to complete.

Source and applicability

This explanation covers the cited GM monitor, not every vehicle carrying this code. The application-matrix filename does not resolve cleanly to this file, so no model or engine fitment is assigned. GM diagnostic table, PDF page 909.