P2603: Read a high coolant-pump control fault as driver evidence

P2603 identifies a high condition in the control circuit for auxiliary coolant pump A. Ford maps it to P2600_12 and describes the malfunction through the smart driver’s output-circuit fault report. “High” here is an electrical classification, not a statement that coolant pressure, temperature or pump speed is excessive.

Keep electrical and operating faults apart

The source lists separate overspeed/dry-run, underspeed, overtemperature and performance entries for the same pump family. Those distinctions matter when several faults are present: one describes the control circuit, while another may describe the pump’s operating response.

The circuit check is continuous, lists a five-second monitoring duration and requires battery voltage of at least 11 V. A reading taken during a different supply state does not recreate that documented window.

Establish the correct circuit before interpreting a reading

Pump A is defined here as the high-temperature-loop auxiliary pump for cabin heating. That source-specific role prevents automatically applying this code to the main mechanical water pump or an unrelated low-temperature circuit.

Preserve the complete subtype, commanded pump state, battery condition and smart-driver fault indication. The summary does not publish a high-voltage cutoff or a connector pin for P2603. Testing and repair decisions therefore need the matching electrical information. A high classification alone cannot determine whether the responsible path is external wiring, the connected load or the control electronics.

Source and applicability

Ford 2024–2025 gasoline OBD summary, July 16, 2024 revision; only the described monitor and architecture. Model, engine and calibration fitment are not inferred. The monitor explanation does not identify a failed part or replace the applicable service procedure. Ford PDF, page 144.