I am looking for the Merc service manual for the new 8.2L 502 HO motor, mine is a 2011. I have a warning beep that happens only once per minute and it is driving us nuts. I do have access to a scan tool, but do not have the new CAN adapter yet. I am also looking for a wiring diagram as well. I had all of this for my 496 HO motor, but so far information online is very scarce. Thank you very much for the help.

Not sure if this will help but this is from my operations maintenance manual (side note) Your power package should still be under warranty I would contact a merc dealerand have them scan for you.

Visual & Audio Warning Systems
Boats powered by emissions control technology catalyzed engines must be equipped with a smartcraft enabled gauge capable of displaying the service engine icon or a dash mounted service engine light. Malfunction indicator lamp kits cantaining a dash mounted service engine light and a special harness that connects to the engine harness may be purchased separately. The service engine icon or MIL will provide a visual indication of a malfunction with the engines emission control and will remain on while the OBD-M fault is active.
(Audio Warning System)
Important-The audio warning system alerts the operator that a problem has occurred. It does not protectthe engine from damage. The power package may be equipped with an audio warning system. Most faults cause the warning horn to activate. How the warning horn activates depends on the severity of the problem. There are two warning horn states (caution) & (severe).
Caution-If a caution state is detected the audio warning system will sound for six (one-second) intervals.
Severe-If a severe state is detected the audio warning system will sound for six seconds, turn off for six seconds, and sound for six more seconds. Then the audio warning will sound for two half second intervals every sixty seconds.

Hope this helps, if this is not the warning you are getting, it could be that your airing your boat out and could be hitting your rev-limit or not throttling back soon enough for your drive.

if you dont have a vessel view or other smartcraft gauge then you will need a mercury dealer with a cds (computer diagnostic system) with mercury's g3 system to read the code on the new 8.2. i dont think a scan tool will work, the cable connects to the 10 pin connector where the can terminator is on the engine, not the flat 4 pin diagnostic port like on the 525 or 496.

I have the same motors in my boat. It sounds like the same thing that happened to me at the beginning of last season. It's probably because of old gas you stored the boat with from last season, treated or not. The cat motors are very touchy to old fuel, and will do the warning beep thing. It's fine, they're just overly sensitive, a little tape over the warning horn till you can get it in will make things easier to live with. I took it to the closest dealer and had them clear the code (last season) and it never returned. Since it was an emisions issue, the warranty is for 3 years, shouldn't be a charge. You could call Mercury first to get them to document it first though. At the end of last season, I pumped all of the fuel out of both tanks. It's probably the best thing to do anyways with the garbage fuel we have these days! This season, I had no warning horn, it's the fuel and the sensors on these new motors!

Thank you both very much. It appears that the beeping I am having is related to the OBD system. It happens from the time I start the boat until I turn it off, even at idle. I have an appt to take the boat in for warranty work in a couple of weeks, so I will be sure to tape that buzzer Being that I just bought the boat used, I am not sure of the gas that was used or how it was stored, so I would not be surprised if that was the case. It is just nice to hear it is not a more serious of a problem. There is such a lack of information out there on this motor, it makes it difficult to diagnose.

Gonzo, When I was searching online for wiring diagrams, one of the results was a youtube video of you shooting across Lake St. Clair, very cool vid. I miss that lake!

Thank you guys again for the help.