I have 496 HOs with CMI headers, fully stock otherwise. Every once in a while, my port motor gives me a beep code, and I believe it is only happening at idle and when the motor is quite warm (after moving pretty good for a good while). But, by the time I get the scanner out of the cabin and hook it up, the beep stops and the scanner does not show any stored codes.

The beep code is single beep - pause - single beep - pause - single beep - etc.

So, questions for you 496 experts and/or Merc ECM experts:

1. What codes are stored and what codes are not stored? Is a "single beep - pause - single beep - pause - etc" pattern a live error only and not stored. And, a "double beep - pause - double beep - pause - etc" pattern results in a stored code?

2. Any idea what my malfunction could be? I'm thinking IAC since it seems to only happen at idle, but I know for certain that I get a stored IAC code when the IAC completely burns up and fails (been there a few times!).

Thanks for any insight!

Ed

I had a bad IAC on a 496 and I don't remember the alarm ever sounding or a code being stored.

You should be able to display the IAC output on your scan tool. If the IAC is working, the level should be fluctuating at idle. If it is flat lined, your IAC is bad.

Check my older posts, I had a chart for beeps posted in it.

I believe this is the link:

http://www.offshoreonly.com/forums/p...save-info.html

Thank you

Thanks for the responses. The beep code chart is helpful.