P2B58: coolant flow valve motor-driver current above its limit

The cited P2B58 monitor checks current through the DC motor driver for the engine coolant flow control valve. Its threshold is above 5.5 amperes. The hardware input/output layer supplies the error information, so this is a driver-current diagnosis rather than a direct comparison of coolant temperatures.

Current and position answer different questions

Excess current establishes that the electrical drive exceeded the monitor's limit. It does not by itself establish whether the valve reached its requested position, whether a mechanical load is excessive or which electrical element is responsible. Comparing driver-current evidence with commanded movement and actual valve-position feedback is an editorial diagnostic inference that can distinguish those situations.

The table requires 80 failed observations out of 100 samples, taken every 12.5 milliseconds. It also requires powertrain relay voltage above 11 volts, no engine cranking and an enabled diagnostic system. A low-voltage cranking event is outside the documented enable conditions and should not be treated as a valid reproduction of this monitor.

Reproducing the right event

The row includes a “test failed this key cycle” qualification. Preserve the initial failure information rather than assuming the current monitor will repeatedly report fresh events during one uninterrupted test session. Use the applicable service procedure for subsequent verification.

A successful check should show acceptable driver-current behavior while the valve is commanded through the relevant operation and the monitor is enabled. A normal coolant gauge alone does not verify this electrical diagnosis. The table supplies no universal motor-resistance value or instruction to replace the complete cooling assembly.

Source and applicability

Documented 2025 GM gm-2025-04b monitor only; vehicle, engine and controller applicability must be established separately. GM monitor table, PDF page 850.