P0589: cruise switch B sits between recognized input ranges

P0589 identifies an invalid intermediate value in cruise-control switch circuit B in this GM strategy. The BCM reports the analog input condition to the ECM, which sets the code and disables cruise control for the remainder of that key cycle.

Invalid does not always mean fully high or low

The table defines several gaps between recognized switch ranges using analog-to-digital count ratios. For example, a ratio in the 0.28–0.31 gap is one invalid band. These ratios are not voltages, and the page does not establish a universal switch-terminal voltage for every vehicle.

The failure needs 0.50 second within a 25-second observation period, with the diagnostic and ECM cruise-switch evaluation enabled. A sustained value in a gap differs from a brief transition as a switch changes state.

Why cruise may stay unavailable after the signal recovers

The source explicitly retains the disabled/disengaged state for the rest of the key cycle regardless of the current pass/fail value. A now-normal input therefore does not contradict a prior valid failure report.

Verification should assess the switch-state ratios and whether the input settles into recognized ranges under the correct procedure. The table lists Type B reporting over two trips and does not isolate the switch from its circuit. Do not use public-road cruise operation to compensate for unresolved input-control faults.

Source and applicability

2025 GM 25OBDG04B diagnostic parameter tables; the cited monitor only. Vehicle, engine and calibration applicability must be confirmed separately. These tables describe detection logic, not a complete repair procedure or a component replacement verdict. gm-2025-04b, PDF page 566.