Diagnostic article Generic OBD-II
P2633: Tank-transfer pump circuit-low evidence comes from the tank module
Learn how P2633 combines a short-to-ground report with pump activation and module-voltage context.
Read before applying this article
Documented application
2025 GM 25OBDG07A Part 2 documented monitor only; its application-matrix filename join is unresolved. No model, engine or universal calibration applicability is inferred.
The code alone does not identify a failed part or establish that a vehicle is safe to drive. Confirm the vehicle, reporting module and applicable service procedure.
P2633 is described in this GM file as a low-voltage diagnostic for the tank-transfer pump. The relevant input is the fuel tank zone module’s short-to-ground diagnostic signal. It should not be read as a measured low fuel-pressure result merely because the component is a pump.
Command state changes the interpretation
The row provides two accepted diagnostic-state values. One is evaluated directly; the other is paired with the transfer pump being active. Module crank voltage must be below 14.52 V, with the listed inhibit conditions satisfied. The failure interval is 500 ms and reporting is two-trip.
The active-state branch makes the pump command important evidence. Seeing the code with the pump currently inactive does not establish what state existed when the controller evaluated it.
Build a useful event record
Retain the tank module’s diagnostic status, activation state and voltage at the same event. This distinguishes a controller-reported circuit-low problem from assumptions about mechanical pumping performance. Applicable service information is needed to identify the specific transfer circuit and isolate it safely. The summary does not prescribe opening fuel lines or replacing a pump, and it does not prove which circuit element created the short-to-ground report.
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.
Article source documents
Source checks describe how the text was prepared; they do not certify a diagnosis or confirm compatibility with every vehicle using this code.
Original code reference
Dictionary definition
Fuel Pump B Control Circuit Low
This definition retains its original catalog scope. The article above is limited to its explicitly documented application.
Reference scope
Generic OBD-II definition.
A manufacturer label does not establish the model, year, engine or module to which a diagnosis applies. Read the safety and diagnostic limits.
Definition source
- DTC Database: pinned community code definitions
Source checked · MIT