P0882: TCM supply low is checked outside cranking

P0882 is the transmission control module’s low power-input code. In the cited GM implementation, the controller monitors its battery input directly and excludes cranking from the ordinary assessment. That distinction matters when reviewing a brief voltage drop captured during engine start.

Voltage, persistence and operating state

The failure boundary is input voltage below 8.5 volts, with 250 millivolts of hysteresis and at least 500 milliseconds of confirmation. The key state must not be STOP. The monitor is described as continuous when eligible and carries a type-A classification.

These details are more specific than a general observation that a battery is weak. The relevant evidence is the controller’s supply during the qualified interval, not necessarily a reading taken at a different point or under a different operating state.

Other checks may be inhibited by this code

The same document lists P0882 as a disabling condition for reference-voltage and speed-input monitors. Consequently, clearing secondary codes while the TCM supply remains unqualified does not show that those other systems have completed successful tests.

Preserve the input-voltage history and associated fault sequence. The code does not establish whether the origin lies in the battery, charging system, supply wiring or another path, and it does not condemn the TCM itself. The applicable supply-circuit procedure is needed to localize the drop and then verify the affected monitors after their enabling conditions are restored.

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; GM diagnostic table, PDF page 911; GM diagnostic table, PDF page 919.