P0690: relay feedback stays high after an off command

P0690 detects powertrain relay feedback that remains higher than expected after the relay is commanded off. In this GM example, a feedback value at or above 4 volts increments the failure counter.

Timing begins after the shutdown command

The relay must have been commanded off for at least two seconds before the described feedback evaluation. The sample rule is fifty failures out of sixty-three, at one hundred milliseconds per sample. A voltage captured immediately at the command transition is therefore not the same evidence as persistent high feedback after the delay.

The source gives a relay stuck on as an example, not a proven diagnosis for every stored P0690. High feedback can establish that the expected off-state voltage was not observed without uniquely identifying the component responsible.

Preserve the shutdown context

Record command state, elapsed time after the off command and feedback voltage. Looking only at key-on voltage misses the defining operating state. The source also excludes an active relay-state-related fault, so a separate state fault can affect whether this diagnostic runs.

Verification should include the prescribed controlled shutdown sequence and a passing delayed feedback check. A normal running engine or a successful restart does not demonstrate that relay power decays correctly after shutdown. The table classifies this example as Type B over two trips and does not provide a bypass test or a universal relay replacement instruction.

Source and applicability

Documented monitors in gm-2025-03a, model year 2025. These are module/calibration examples; vehicle, engine and transmission applicability must be confirmed independently. GM 2025-03a, page 421.