P26E6: An off-state starter-relay signal remains powered

P26E6 is the high-voltage electrical classification for the tandem starter pinion-relay circuit. In this GM implementation, the controller evaluates the output while it is switched off. The relevant failure is feedback consistent with an unintended power path in that off state, not simply the presence of voltage during a legitimate start command.

An off command is part of the evidence

The controller compares its measured voltage with implementation-specific thresholds representing a short to power. The source associates that classification with impedance at or below 0.5 Ω toward controller power. These are diagnostic criteria, not a general instruction to bridge or load an unfamiliar relay circuit.

Run/crank supply must be at least 11 V and the starter-control diagnostic enabled. The monitor allows nonnegative engine speed, so interpreting the fault does not depend on assuming the engine was running.

Confirm persistence in the correct state

Forty failed samples out of 50 are required, with a 50 ms sample interval. A transient observed under a different command state is not equivalent to that completed decision. P26E4, by comparison, checks for an open circuit under an on command.

Useful verification preserves the command transition and whether the output behaves as expected after switch-off. The summary does not identify which component maintained the power path or prove a mechanical starter fault. Localization needs the correct wiring and controller test procedure.

Source and applicability

2025 GM 25OBDG03B documented monitor only. Vehicle, engine and calibration applicability must be confirmed from the matching service information; no model fitment is inferred. These criteria explain controller logic, not a complete repair procedure. 25OBDG03B, PDF page 853. 25OBDG03B, PDF page 854. 25OBDG03B, PDF page 855.