Slinger from what I gathered on that last incident the aircrew ran the preflight BIT on the AFCS. He did as any crew would do during prelaunch procedures. Now why the rate sensors didn't fail during this test is odd.
On the F-15E if the rate gyros have a power interrupt the will virtually stop then spin back up. Typically if the aircrew tries to reaccomplish a BIT during this power interruption the rate gyros will fail. They have to wait approximately 2 minutes before they can rerun the BIT. If they don't wait the system will fail for the sensors since they are still spinning back up to speed. On the F-15E a failure from one of these sensors is considered a total no go of the AFCS. The resulting failure of the gyros will not allow their CAS to reengage which is a clear indication of a problem.