P26B9: coolant bypass valve C driver reports a power short

P26B9 identifies a short-to-power condition reported by the coolant bypass valve C H-bridge driver. The cited strategy monitors the energized circuit and includes separate opening and closing branches.

What the two branches mean

For opening, the motor must be commanded in that direction and the closing-direction power-short fault must be absent. For closing, the opposite-direction qualification is reversed. Diagnostics, run/crank and driver-status validity must be acceptable, with no engine cranking. The decision uses the driver's shorted-high report, not coolant temperature or a published position error.

Both branches show an impossible-looking timing entry of 999.9 seconds within a zero-second window. No reliable setting duration can be obtained from that cell. The table still identifies Type B, two-trip reporting, but calibration-specific timing needs confirmation.

Verification

Retain motor direction and the driver report at the fault. A high signal measured at an arbitrary point without command context is not the documented diagnostic test. Distinguish this motor-control fault from a high digital position-sensor value.

Use the appropriate service information to determine the physical circuit and corrective action. Confirmation requires the relevant energized-direction check to complete without a power-short report. Neither valve motion nor a cleared warning alone establishes that outcome, and the timing defect should not be interpreted as proof of normal operation.

Source and application limits

This explanation covers the cited 2025 GM monitor. Confirm the vehicle and calibration in its service information before applying these limits; inclusion in this file does not establish model compatibility. GM diagnostic parameters, PDF page 846.