sporadic cut outs with low voltage alarms

[DAN0]

I have a 2018 115 merc Model 1115F531D serial# 2B511030 that cuts out periodically, causing a sudden jerk in motor or pause. I would get an occasional alarm of a single beep that got progressively worse to a long beep that required going to neutral on throttle to stop alarm. However, next time using motor, no issues, it runs perfect. Changed plugs, fuel filter and gas to no avail. Had certified merc tech look at it and couldnt determine if it was a wire harness or ECM. Alerts are a 601 code, low voltage. Batteries and connections test good. Since it is a periodic problem, techs can not isolate problem.

Any suggestions are appreciated.

Don any words of wisdom

Below is a link to video that shows when the motor cuts out.

https://lakeminnetonkafishing-my.sha...qr3mw?e=arqlBB

[EuropeanAM]

Welcome to BBC!

Might want to look around inside the cowling to see just what might be getting WET. That engine is buried pretty deep, and there's spray on virtually every square inch of the cowling, so it's conceivable that you're pulling in water that could be causing problems.

What is the battery voltage, at the battery, with the engine OFF, and then 5 minutes after starting engine (continuing to run engine)?

If you raise RPM's slightly, what is the voltage?

[DAN0]

Thanks for the reply. I just looked around after using it and didnt see anything wet inside.

Volts at battery when off is 12
Volts when first starting is 14
Volts after running 5 min is 14
Volts at about 1200 rpm is 14, my gauge is not digital... it might have been 14.5...

[EuropeanAM]

Were you taking those with a test-voltmeter (ie: a DVOM) connected TO THE BATTERY?

[DAN0]

Yes, my analog test-meter has posts I touch to battery directly not clamps.


Also, would you have any concerns if I swapped out the ECM with another merc 115 (I think it is a 2019) to see if my engine still acts up?

[Frikster]

Not sure if its the case with mercury, but i used to have a yamaha SHO 250, it happened to me just like you explained, turned out that the motor needed a battery connected to run, so in other words should you start your engine and have it idle and remove a terminal from the battery the engine would die, so what i am getting to is to remove your battery clamps , clean them and reinstall them, a bad connection due to being loose or having that buildup you normally get on your terminal could cause it also, like i said not sure if the merc works on the same principle , its easy enough to try, hope you get it sorted bud!

[EuropeanAM]

As long as it's the same calibration number, that would be a simple way of ruling out the PCM. I'd be quite surpised if it was the PCM, though.

[DAN0]

As long as it's the same calibration number, that would be a simple way of ruling out the PCM. I'd be quite surpised if it was the PCM, though.

Thanks - Yes, just trying to eliminate possible problems. When you say "same calibration number" what do you mean or how can I check if they have the same calibration number? Any concerns with static electricity if I have the one shipped to me? I have it on another boat in another state...

[DAN0]

Not sure if its the case with mercury, but i used to have a yamaha SHO 250, it happened to me just like you explained, turned out that the motor needed a battery connected to run, so in other words should you start your engine and have it idle and remove a terminal from the battery the engine would die, so what i am getting to is to remove your battery clamps , clean them and reinstall them, a bad connection due to being loose or having that buildup you normally get on your terminal could cause it also, like i said not sure if the merc works on the same principle , its easy enough to try, hope you get it sorted bud!

Thanks! I have removed and tightened the connections. They are clean, so didnt need cleaning them. I like easy fixes, but all seems well with the connections.

[EuropeanAM]

Thanks - Yes, just trying to eliminate possible problems. When you say "same calibration number" what do you mean or how can I check if they have the same calibration number? Any concerns with static electricity if I have the one shipped to me? I have it on another boat in another state...

Same numbers printed on the white label (NOT the Motorola label, the larger label). If not the same precise number, do not use.

[DAN0]

Okay - Thanks!

[DAN0]

Same numbers printed on the white label (NOT the Motorola label, the larger label). If not the same precise number, do not use.

This number should match? AE&0150C02C See attached photo2018merc.jpg Thanks Dan

[C.Warrix]

Dano, Any luck finding the issue youre having?

[DAN0]

Dano, Any luck finding the issue youre having?

No - still trying to isolate...

[thommo59]

Do you have a battery isolation switch between the battery and engine? I had low voltage alarms on start up a few years back due to this switch. If you do, you can test this by by passing

[EuropeanAM]

ie: Connect engine positive cable DIRECTLY to cranking battery (bypassing the battery switch).

[DAN0]

Do you have a battery isolation switch between the battery and engine? I had low voltage alarms on start up a few years back due to this switch. If you do, you can test this by by passing

I dont have a battery switch. The cable is direct from motor...

[DAN0]

ie: Connect engine positive cable DIRECTLY to cranking battery (bypassing the battery switch).

No battery switch... This is a Sun Tracker Pontoon boat. Very basic set up, no bells or whistles.

[SPORTMOD25]

sounds to me like it could be shutting the engine down for a quick second and the alarm is the start up alarm again. had a engine once that the pcm was picking up electrical interfernce from the engine harmonics. try ohm testing the pcm to ground both with the engine not running key on and engine running and see what the readings are and compare to a know good engine. had to replace the pcm on the problem engine i had

[EuropeanAM]

This number should match? AE&0150C02C See attached photo2018merc.jpg Thanks Dan

Actually, not only do those need to match- the OTHER LABEL (seen at the bottom of the photo) ABSOLUTELY MUST MATCH (or appropriately supersede via parts catalog).