Guardian mode with no audio alarms

[TimsTahoe]

I have a 2012 4.3L MPI Serial # 2A049240 with a PCM0905. When i turn the key on I get a single short tone from the alarm and hear the fuel system pressurizing. Once that finishes an amber dash light comes on. Engine Starts and all gauges seem to be fine oil pressure, water temp, and volts. Engine idles fine right up to about 3500 RPMs and then won't do any more. I assume it is in guardian mode, but with no audio alarms, I am at a loss of where to even start. I thought it might be fuel related since the light comes on as soon as fuel system finishes pressurizing. Changed Water Seperator and checked all fuel lines. Nothing seems to be jumping out at me. Any Help would be greatly appreciated. Hoping something simple that I am just ignorant about...

 

[alldodge]

Welcome and thanks for the serial number. Your serial number shows you have Cats

To find out what's wrong most likely you will need either Techmate Pro or Diacom software from Rinda

TechMate Pro (94070m)​

Diacom 94030g Kit​

RINDA
The new motors need a scanner to find out what the issues are

 

[TimsTahoe]

Thanks!! I just found a video on how to get the error codes using a paper clip and a multimeter. I think I will try that first. I know hope is not a plan,,,, but hoping there is very little or no risk to at least seeing if that works/helps????

 

[alldodge]

Thanks!! I just found a video on how to get the error codes using a paper clip and a multimeter. I think I will try that first. I know hope is not a plan,,,, but hoping there is very little or no risk to at least seeing if that works/helps????

That won't work in your case. The paper clip method only works on MEFI ECMs

 

[muc]

On your engine I haven't seen any faults that triggers guardian but doesn't sound the warning horn, except PCMs that have an updated calibration to reduce nuisance horns. But I haven't seen everything!
Is it possible that you're trying to exceed 3500 RPM in neutral? I'm pretty sure your engine won't allow that. But that usually will set a horn.
I'm guessing the amber light you mention is the OBD-M warning light. But the way that light should work is, at key on the light should come on immediately and stay on for 4 seconds as a system check and then turn off. If it stays on that means a fault has set and is still active. If this is happening with no audible warning, that usually means there is a problem with the emissions control. Continuing to operate the engine risks burning up a few thousand dollars of catalysts.

You may find a lot of value by taking your boat to a MerCruiser dealer with at least one good tech.

 

[TimsTahoe]

On your engine I haven't seen any faults that triggers guardian but doesn't sound the warning horn, except PCMs that have an updated calibration to reduce nuisance horns. But I haven't seen everything!
Is it possible that you're trying to exceed 3500 RPM in neutral? I'm pretty sure your engine won't allow that. But that usually will set a horn.
I'm guessing the amber light you mention is the OBD-M warning light. But the way that light should work is, at key on the light should come on immediately and stay on for 4 seconds as a system check and then turn off. If it stays on that means a fault has set and is still active. If this is happening with no audible warning, that usually means there is a problem with the emissions control. Continuing to operate the engine risks burning up a few thousand dollars of catalysts.

You may find a lot of value by taking your boat to a MerCruiser dealer with at least one good tech.

muc - Definitely NOT related to being in Neutral... However you are pretty close to describing the start up and my light... When I turn key to "on" I get a short audio alarm (normal) and then hear the fuel pump for a few seconds (normal), but that's when the light comes on and it stays on indefinitely (well until the key is turned off) ... this is all before starting the engine. The "few thousand dollars" statement convinced me to quit dinking with it ... I guess am going to take your advice and limit running it anymore except to load on the trailer... Will do the 2 mile run to the ramp with electric trolling motor on my way to mechanic.... I will let you know how it turns out. Until then thanks everybody