Bear in mind this SB is more intended to take care of a just realized manufacturing, limited time “warranty” work for anyone experiencing odd issues that can’t be found after inspection of a lot of other possibilities beforehand and not really meant for general boating forum websites especially back then in 2003.
They identified where a problem lies throughout the whole system with a possible few repair areas/ideas and warrantied the main internal issue and making the repair as easy as possible for all in the moment by just swapping ECM’s that are calibrated correctly for the shift interrupt system.
Back then dealer recalibration was more or less just starting out to where not everyone was fully equipped plus trained enough to perform/accomplish the task so swapping was easier for them still depending on who’s working on it and where if it was even possible for the event being discussed… < I’m not sure honestly…
This test recommendation only came after noticing the year and serial number range and drive application and while the symptoms might not be an exact worded match in the bulletin, in the past I had seen different odd issues where this test helped so while it’s not a guarantee, it’s an easy to try test to eliminate a possibility should you make your next boating trip a concentrated find and fix it type trip vs say an entertainment family day outing.
If this where to be the problem, it was once mentioned by a Merc warranty authorization tech representative that the issue might be resolved if the shift plate assembly were to be moved off the engine and mounted say on the transom of the boat as the ECM was supposedly seeing to much movement/vibration and adjusting accordingly due to miss calibration.
I never tried the described vibration theory, so I cannot verify a guarantee to it.. could it be a bad switch if the test plays out, maybe.
