2016 Merc 8.2 low voltage drop Kills engine

[searay12950]

Hello I have 2016 sea ray slx twin 8.2 MAG ECT Axius Bravo III …in the attached video you will see OBDSTAR screen showing my Starboard system voltage (which I’m assuming is ECU voltage?) go from 13v to a quick blip of 0.00, this happens often and sometimes is not a blip but a full drop to zero, and then in 5-30 minutes will have system volume back to 12 plus volts. The port engine is fine with no issues this happens only on Starboard engine.

When I’m on the water randomly the engine will be power fine and just die…every time it reads 12-13v battery voltage and 0.00 system voltage.

I have checked and replaced the Main relay, I have installed a new Alternator, I’ve checked all fuses, I’ve put a new Clean Power wire in, I have tested all batteries, I have tested and checked both port and starboard ignition keys.

I’m running out of options , my only thought is maybe an Ecu fail of some sort? Does anyone else have an idea for me

 

[Bondo]

I have checked and replaced the Main relay, I have installed a new Alternator, I’ve checked all fuses, I’ve put a new Clean Power wire in, I have tested all batteries, I have tested and checked both port and starboard ignition keys.

Ayuh,....... Welcome Aboard,........ Remove, 'n Clean to shiny metal, both ends of both(or all) the battery cables,.....

 

[cyclops222]

I see a loose connection. 2 people working together. 1 watches the screen for the voltage error to appear. Other is CAREFULLY lightly touching wires in connecting plugs. To cause loss of voltage to appear. I would shut down system And carefully pull apart and reconnect each plug to clean off mating surfaces. Get lucky.
Most plugs will have a tiny locking piece on the plug to hold the plug in place. Gently squeeze the tab to allow plug to be removed. Gently squeeze.

 

[Fun Times]

You may want to ensure that the battery switches aren't having any connection type issues at the wiring and that the switches are positively switching/clicking into place of 1 or 2 or All and not losing contact to the wiring thus supplying proper power voltage and not having an odd disconnecting type of issue internally...also be sure you are not leaving one of the battery switches in the off position as you probably have 2 switches?.

Also be sure that all the wiring at the engine starter connecting posts are clean and tight as some power could be lost in that area too... Does it seem as if maybe the engine starter is now a bit slower while turning over along with engine starting time increased some vs the other engine too?

I'm thinking you may want to read post number #102 and #115 but the whole thread may be a good overall guide too to help get your diagnostic skills in order for this one.

Mercury 6.2 ECT DTS Axius Voltage Issue

. . . the hits just keep on coming . . . I've been doing a bunch of work on my boat and engines . . . mostly of the electrical nature. Anyway, I am getting low voltage warnings on the starboard engine. Once the engine starts the warning goes away and the VesselVeiw says "OK". I then noticed...

forums.iboats.com

https://www.marineengine.com/boat-forum/threads/mercruiser-vesselview4-low-voltage-warning.473120/

Also be sure you're following sequence of powering up and down all the voltage systems as that could have an effect of power fluctuations and possible odd time wise situations...The following is an example of what would be right and what is wrong to do,

Fault code on smart craft

PRO XS 225 SER.#2B737621. So I’m sitting in my boat and I turn the key on..The gauge lights up as if it’s getting power.My battery selector switch is off ,so I’m surprised there is power to the gauge.I then tried the trim switch and nothing happens.Then the sc1000 gives me a fault code of...

www.bbcboards.net

@tpenfield , It seems your (Past?) voltage problem is possibly more common on the internet than first thought... Did you come across this one in your searches of more help too?

Incorrectly displayed system voltage

On our 2012 310 (twin MAG 350 B-3) our starboard “battery voltage” is incorrectly shown on vessel view, gauge, and in scan data. I’ve verified the lower than actual voltage with a DVOM at the engine, alternator, and battery bank. It’s accurate when the engine is cold and shut off. Running, it’s...

www.clubsearay.com

 

[searay12950]

Quick update, been trying to upload images to show the random voltage drop in the “SysVolt” aka system voltage and then separately the “BattVolt” aka Battery Voltage from my OBdstar scan tool.
Basically both Ecu show random SysVolt drop , battery graph stays perfect just Sysvolt drops, is this inherit of Merc Ecu?
Basically my starboard Syscolt drops and then will randomly not recover

 

[tpenfield]

@searay12950 I have the 2016 6.2L engines and went through similar voltage issues a couple of years back as well as earlier this year. I have the Diacom computer software for trouble shooting . . . sometimes trouble-making

Anyway . . . What I learned is that the 'system voltage' is the battery voltage (via the clean power feed.) The 'battery voltage' is actually the voltage from the ignition switch (via the purple wire). It would seem (to me) that the labeling of these voltages should be reversed.

I'm not sure if your OBDStar tool has the same mis-match. but . . . It sounds like you have an intermittent connection on the ignition (purple) wire. I would check that first. If you go through my thread 'DTS Axius voltage Issue' that @Fun Times posted, it may help with your diagnosis.

I had both an alternator and a battery isolator problem. I believe you have twin engines, so the engine power of each engine needs to be isolated (separate from one another).

 

[cyclops222]

That could be a real problem if someone turns the LARGE Battery Switch to the BOTH position.

 

[searay12950]

@searay12950 I have the 2016 6.2L engines and went through similar voltage issues a couple of years back as well as earlier this year. I have the Diacom computer software for trouble shooting . . . sometimes trouble-making

Anyway . . . What I learned is that the 'system voltage' is the battery voltage (via the clean power feed.) The 'battery voltage' is actually the voltage from the ignition switch (via the purple wire). It would seem (to me) that the labeling of these voltages should be reversed.

I'm not sure if your OBDStar tool has the same mis-match. but . . . It sounds like you have an intermittent connection on the ignition (purple) wire. I would check that first. If you go through my thread 'DTS Axius voltage Issue' that @Fun Times posted, it may help with your diagnosis.

I had both an alternator and a battery isolator problem. I believe you have twin engines, so the engine power of each engine needs to be isolated (separate from one another).

@tpenfield and @Fun Times
Thank you everyone for your help!

So I went through checking all wires etc as suggested by @cyclops222 and my problem ended being the red wire off the starter solenoid. When I would grab it I could here the main relay clicking this short the SysVolt

I think I finally have it and am going on sea trial today. I can’t thank everyone enough for your help!

 

[tpenfield]

That could be a real problem if someone turns the LARGE Battery Switch to the BOTH position.

No 'Both' battery switch position on these boats and many like it. Just simple on/off for each battery bank.

 

[tpenfield]

@tpenfield and @Fun Times
Thank you everyone for your help!

So I went through checking all wires etc as suggested by @cyclops222 and my problem ended being the red wire off the starter solenoid. When I would grab it I could here the main relay clicking this short the SysVolt

I think I finally have it and am going on sea trial today. I can’t thank everyone enough for your help!

Great! let us know if that resolved the issue.

 

[searay12950]

Sea trial went great!
I have to tell you all how much I appreciate the help. Had a local mechanic do a bunch of work on boat but he was stumped on this intermittent issue and to be honest I think he was silently giving up …just going in circles at my outing and family expense.
So I tackled it and have about 20 hours in but glad it’s finally resolved. Wife told me yesterday I had one more day to fix or boat is gone …it was an early morning with the headlight but got it done , thanks all again

On separate note for the money I highly recommend the OBDSTAR mercruiser setup. Bought off eBay and was skeptical but after doing update and learning the OS it really helped me out.

 

[cyclops222]

I have found many people just put the BIG battery switch in BOTH. And do that for reliability. I do not bother to discuss what they are doing when a battery shorts out.