P2402: EVAP pump driver detects unwanted power during its on command

P2402 identifies a short-to-power condition in the leak-detection pump's low-side control circuit in the reviewed GM conventional vented EVAP system with fuel tank zone module. It is an electrical diagnosis, not a direct measurement of pump flow or tank sealing.

The commanded-on response is evaluated

The controller checks driver voltage when the output is powered on. Voltage outside the accepted range indicates the short-to-power signature. The listed controller design specification is less than 0.5 ohm between output and controller power.

The source also describes a specific follow-up behavior: when P2402 is active, an intrusive test commands the pump on for 15 seconds. Seeing a pump command during fault handling may therefore be part of the diagnostic sequence rather than ordinary leak-test operation.

Counted evidence and communication

The monitor uses 50 failures out of 63 samples at 250-millisecond intervals and excludes an EVAP-device communication fault. A command observed without valid communication or feedback does not establish the circuit's response.

Verify the vehicle's actual system architecture before applying this description. Use its service procedure to distinguish an unwanted power path from a load or driver problem; the summary's impedance specification is not a live-circuit testing instruction.

A completed repair should restore acceptable on-state electrical behavior and prevent recurrence through the applicable test. The source lists Type B, two trips, without establishing a defective pump assembly or a vapor-system leak.

Source and applicability

The documented control architecture and calibration require confirmation for the vehicle being diagnosed. GM diagnostic table, PDF page 648.