P2689: fuel-heater feedback remains high during an on command

P2689 describes the high-circuit branch for the fuel-filter heater control driver. In this GM implementation, voltage stays high when the low-side driver is commanded on. The controller interprets that relationship as a short-to-power condition.

On-state feedback is the useful distinction

A high value observed when the circuit is expected to be off does not reproduce this monitor. Record the heater command at the same time as its feedback and driver fault status. Without that context, the word “high” can be mistaken for high fuel temperature or an unrelated charging-system event.

The neighboring low and open-circuit diagnoses use a different commanded-state interpretation. Their existence does not justify swapping parts until the specific high-circuit behavior has been confirmed through the correct wiring procedure.

Supply and engine conditions still matter

The source requires a stable battery voltage above its threshold, an engine-speed limit selected by calibration and the stated post-drive conditions. The fault must persist for two seconds, with evaluation on a 0.2-second cycle when enabled. A reading taken outside that window may help troubleshooting but is not the completed monitor result.

This parameter table contains no vehicle-specific pinout, disassembly instructions or automatic heater-replacement rule. A technician should establish the actual control path and use the appropriate fuel-system precautions. After correction, verify that feedback follows the intended command during an eligible evaluation and that related faults or the original operating complaint have been resolved.

Source and applicability

GM 2015 15OBDG04 fuel-filter heater driver monitor. Only the cited monitor and calibration are described; per-code vehicle and engine applicability has not been established.

15OBDG04 Engine Diagnostics, physical PDF page 254.