Trying to bypass Trim Limit Switch on 2006 MCM 350 Mag MPI, with Volvo SX outdrive.

[c1steve]

I am beginning to think that the Guardian Mode is coming on from a different reason than the lack of Trim Limit Switch. What about the Gear Interrupt switch. My notes say this is open when in gear, though. Note that the engine does not go into Guardian when in neutral/no load.

 

[Fun Times]

Do you still have access to a scan tool? They've switched that switch around a few time from normally open to close or vice versa so hard to tell what one or way to go with it. Normally connected correctly you shouldn't be able to go over 3800 RPM max in neutral. If you have the scan tool, go to in gear on the live data and see if it says yes or no. May want to plug the switch in and press the button in and out to see if there are any changes in speed hopefully with a scan tool connected so you can see what's happening if any.

The serial number is showing the engine to be an MERCRUISER 350 MPI BRAVO HORIZON 350 MAG BRAVO MPI

I have been told that these codes will not trigger the Guardian Mode.

Yes it shouldn't but has been known to on some engine models including sounding the warning horn even though the charts say it shouldn't. http://forums.iboats.com/forum/engin...481-trim-fault

Also see charts near the end of the page,
http://www.justanswer.com/boat/6f63w...ght-boat.html#

So it's hard to say for sure one way or another.

Your Gear Interrupt switch should have already had a jumper cap installed being a bravo drive from new.

 

[c1steve]

Fun Times,

Thanks for the recommendations. I am coming to the conclusion that the Merc. rep's recommendation on the Trim Limit switch is not correct for my engine, as there is absolutely no connection for it on my engine harness. I will go out on another test run asap and read the live data.

 

[muc]

Volvo outdrives don't have a trim limit switch. What drive do you have?

 

[c1steve]

Found the problem! It was the sea water pressure sensor! On the test run my Rinda TechMate Pro did not measure this, nor did it look at ECT. My TechMate showed the Guardian Fault cause to be "unspecified". I brought down a mechanic from a local shop, who had the Diacom software on their laptop. He looked at the recent Guardian faults, and they were all for low water pressure. The measured pressure was around 2 psi, whether at idle or 3,000 rpm.

I will order the MCM part, test it under way, and possibly design a resistor system to simulate correct water pressure. I can easily check and or replace the impeller every 1-2 years, and would prefer a simpler system. However having gauge reading the water pressure might be handy.

Thanks so much Fun Times and Bt Doctur, and all others for their help and suggestions. I have spent tremendous amounts of time trying to track this down, this is a huge relief.