Fast Codes
WARNING: This page is about a different car, the 1994 Mazda Navajo. However, it is still accessible from the selected car via links, so may be relevant.
At start of KOEO SELF-TEST and after Wide Open Throttle (WOT) request in KOER SELF-TEST, PCM outputs short bursts of information, known as FAST CODES. These codes are used by manufacturer during assembly and are not visible on most equipment. Entire code sequence lasts less than 1/2 second. If this fluctuation is visible on test equipment, ignore it.