2003 Tige 24v - alarm beeping intermittent above 2500 RPM

[toastie22]

ok, so first time out in my (new to me) '03 24v limited.
Runs great, but when RPM goes above around 2500, it triggers an intermittent but consistent alarm beep, which won't go off until the engine is turned off.
I have tried to attach a video of this from yesterday, which shows the gauge readings for temp / oil pressure and volts at the same time - no apparent issues there, but the forum won't allow Mov files (I'm on an apple Mac) The beeping is about 1 second long, with about 10 seconds gap between, and this just keeps going regardless of dropping revs below 2500. Marine mechanic here (who is a long-time inboard mechanic with his own Malibu wake setter), has said that if it was serious engine alarm, it would be constant, but this is intermittent, but consistent. After leaving the engine off while the kids swam in the lake, it started fine, and didn't trigger the alarm again until I ran over 2500 RPM.
Can this beeping be electrical related?
The engine runs fine throughout the rev range, and we had the kids wakeboarding at around 2800RPM, and no temp or oil pressure issues - just the beeping.
I plan to get it back to the mechanic this week so he can plug in his computer to check stored data, but any suggestions would be VERY grateful received.
I can email the video to anyone who's prepared to listen if it helps understand what kind of beep it is. It's a 22 second video.

[lee]

Voltage looks low. With engine running, voltage should be 14 volts if alternator is working properly.

[toastie22]

Voltage looks low. With engine running, voltage should be 14 volts if alternator is working properly.

ok, thanks for that Lee - so I should get the marine electrician to check and perhaps (likely) replace the alternator?
Would low voltage trigger that kind of alarm with intermittent beeping?

[lee]

Tell to check the voltage output of the alternator with the engine running. Sometimes the output wire on the back of the alternator becomes corroded and does not make a good connection. Yes, low voltage will cause the alarm to sound.

[toastie22]

will do - thanks for that Lee.
I also came across an older post referring to the soft alarm being triggered by a loose wire / bad connection to the knock sensor - have you come across this? where would the knock sensor be and what does it do?

[lee]

Knock sensor detects a knock in the engine and regulates the timing. With voltage only 12 volts with the engine running, i would check that first.

[toastie22]

Knock sensor detects a knock in the engine and regulates the timing. With voltage only 12 volts with the engine running, i would check that first.

Thanks Lee - does the ECM records soft alarm data at all?, and what is the connector required to connect a laptop to the ECM - just so I can provide the mechanic here with as much info as possible. Thanks

[lee]

https://www.rinda.com/marine/diacommarine.htm This is what most shops will use.

[toastie22]

Thanks Lee - does the ECM records soft alarm data at all?, and what is the connector required to connect a laptop to the ECM - just so I can provide the mechanic here with as much info as possible. Thanks

So I had the alternator replaced, but still soft alarm going - ECM finally connected and it showed cam sensor and knock sensor faults - replaced cam sensor, and there was no knock sensor - just a brass plug, so mechanic fitted a knock sensor and attached the wire, and that's solved the soft alarm.
Volt meter (new) was still not showing much more than 12v when running, so he ran a direct wire and it's now showing 14v - sorted.
Last issue now is starter - I think you put a new one in Lee for the previous owner, but it started playing up last week - turn key to crank position and just nothing, (has 2 brand new batteries) so we replaced the starter with another identical one and that was good, although I did have two brief instances of the same fault on this new starter this weekend, which is only 1 week old. Turn key to crank, and nothing. no sound of any sort, and no cranking, but try again a couple of times, within 30-40 seconds, and eventually it starts, just like it should. Is there a solenoid that's separate to the starter that could be the issue?

[lee]

The solenoid is on the starter, should be. There is a starter relay by the ecm that could be going bad.

[toastie22]

Got it, thanks Lee. Checking it - will replace the relay to be sure.