P26A7: high valve feedback is not proof of a fully open bypass

P26A7 is the high position-feedback circuit diagnosis for this GM coolant-bypass valve. The source calls the signal out of range. A high electrical reading is not equivalent to independent proof that the valve is physically at its fully open position.

The monitor uses repeated reference-relative readings

The failure criterion is feedback above 95 percent of reference voltage. Forty of fifty samples, spaced at 100 milliseconds, must fail while system voltage is above 10.2 V. That sample requirement distinguishes the stored diagnosis from a single transient observation.

The reference-relative wording matters when interpreting scan data. The table does not provide a universal external voltage that applies to every valve or controller. The correct wiring and reference-supply information are needed before deciding what an actual measurement means.

Resolve the signal before trusting movement tests

GM lists P26A7 among the faults that inhibit relevant valve-position and learning checks. If the feedback is electrically invalid, a controller may be unable to judge whether a commanded movement was completed correctly. A simultaneous performance complaint should therefore be interpreted with the circuit fault in view.

The source does not mandate a new valve assembly and does not identify a specific harness location. A technician should establish the cause through the matching thermal-system and electrical procedure, observing the precautions for hot coolant and any hybrid equipment. Verification should show a credible signal throughout an eligible evaluation, followed by the applicable valve-function checks.

Source and applicability

GM 2015 15OBDG01 HCP2/VICM coolant-bypass valve monitor. Only the cited monitor and calibration are described; per-code vehicle and engine applicability has not been established.

15OBDG01 Hybrid Diagnostics, physical PDF pages 567, 568.