P2634: A transfer-pump circuit-high code is not a pressure-high code

The generic fuel-pump-B circuit-high title becomes a tank-transfer pump diagnostic in the cited GM implementation. P2634 uses the fuel tank zone module’s short-to-battery status. The high classification therefore concerns an electrical report, not excessive fuel pressure.

Include the continuation page

The criterion begins on page 882 and continues on page 883. The row accepts one diagnostic state directly, or a second state with the transfer pump inactive. It also lists module crank voltage below 14.52 V, a 500 ms interval and two-trip reporting. Ignoring the continuation loses the pump-state part of the logic.

This off-state branch is why a fault should not be dismissed simply because the transfer pump was not commanded to run at the observation time.

What verification should retain

Preserve the tank module’s reported electrical fault, pump activation state and voltage together. A pressure reading alone cannot verify this circuit classification. The specific pump identity and circuit routing require vehicle service information; the generic letter is not a universal location map. The summary does not isolate wiring, electronics or pump internals as the proven cause and supplies no fuel-system disassembly instruction.

Document scope and source

2025 GM 25OBDG07A Part 2 documented monitor only; its application-matrix filename join is unresolved. No model, engine or universal calibration applicability is inferred. These figures explain the cited controller logic, not a vehicle-specific repair instruction. Match the vehicle’s service information before applying them.

GM physical PDF page 882, GM physical PDF page 883.