Mercury 6.2 ECT DTS Axius Voltage Issue

[Fun Times]

Teds Luddite build coming next.....

Lol,...There was a time when this was easy for me to help figure out...All Ted and AD are doing lately is making sure I myself don't buy anything "new" too.

 

[Fun Times]

View attachment 399013

Ahh yes, the good old days..

 

[tpenfield]

FWIW - Here is a diagram of where stuff is on the engine. Most of the stuff is tucked under compartments in the plastic cover, so it is a bit tricky to reach. I usually have to un-button everything

I am getting battery voltage at the back of the engine, but I'm thinking I should check the voltage in/out of the 50 amp CB at the front of the cover (also nearly impossible to reach)

 

[tpenfield]

No problem, next time you're in there try to take a peek.
I'm thinking if the wire is orange then it's a stock set up and running down by/to the engine starter...If red then usually something aftermarket with an isolator of some sorts mounted elsewhere....Try to follow the wire just so you know what's going on and if it could be a potential issue on top of anything else.

OK - I'll get my contortionist outfit on and take a look I believe it is all stock set-up, but I'll check.

All of the wiring is jacketed in the black conduit stuff or wrapped into a harness right up to the connectors. . . tough to see the actual wires.

 

[tpenfield]

Thanks for everyone's help on this . . . The inputs help from getting tunnel vision, which is easy to do on things like this.

I have the outdrives waiting their turn for TLC. The gear oil is black as coal and the port drive has a delayed shift. Probably will do the poor man's clutch fix on both of them.
.

.

 

[Scott Danforth]

Ted, are the relays diode suppressed?

 

[dubs283]

When referring to clean power it is important to understand the clean power connections and harness have nothing to do with mpr, other relays or circuit breakers

The clean power connections and harness are simply solid, unmolested, fused (+) and (-) connections for the pcm. This guarantees the pcm always has a solid 12 v (+) and (-) connection from the main engine battery(ies). Without this connection the engine will not run

It's possible you have an issue with the clean power or the main circuit breaker on the engine but keep in mind these are two different and to a point unrelated circuits

If was getting intimate with your bilge based on the info posted I would focus on the battery switch connections for the engine in question, all grounds, and look closely at where/what was removed/replaced for the alternator r and r. Possible a pinched wire at the pcm/relay harness area on top of the engine?

 

[tpenfield]

Ted, are the relays diode suppressed?

I feel more suppressed than the relays . . . or would that be depressed, not suppressed.

Anyway . . . based on the diagram of the relay, I am thinking it does not have a diode.



I've looked online for specs, and it mentions "diode & resistor versions available".

Although the relay is a 5-pin automotive type, IIRC, the connector is 4-pin (omits 87A).

I'll be tracing some wires over the next few days

 

[tpenfield]

FWIW - I went through the 2 years of maintenance history from the prior owner's marina (they gave me a print-out) and there was nothing mentioned about low voltage warning or electrical stuff.

Interestingly, some stuff that they checked or fixed, I am finding are still issues (port engine coolant leak, port outdrive operation).

The starboard engine voltage issue was present at the pre-purchase survey. I recall fixing it by messing with the clean power CB and combining the inverter battery bank with the accessory bank (1 battery). It was fine for 2 years . . . and then there is now.

 

[nola mike]

One thought that comes to mind to consider trying as well would be while the relay is buzzing, start pulling one fuse at a time all over the engine to see if maybe one of them is back feeding but pull the Main relay fuse last if possible.

Also is this happening when the boat's other house power is powered up too?

Maybe it's a bad diode someplace.

This is pretty much what I was thinking. Probably easier to pull fuses than pull wires. Didn't think of a diode (mine only has one buried in the alt I think); I wonder if there's one separating the different batteries somewhere. This really seems like a "too much power where it shouldn't be" problem rather than a "not enough power to where it should be" issue.

 

[tpenfield]

A couple of updates in answer to some of the questions . . .

The buzzing only happens when the stbd engine switch is turned off.

Turning the other switches (house and port engine) off/on do not seem to matter.

If I turn the stbd engine switch back on the buzzing immediately stops.

 

[tpenfield]

Meanwhile . . . I am away from the boat for a day or two. So, I am trying to map out the power connections from the massive diagram that I posted.

I have a feeling that there is a bad connection (or a short) somewhere that is dragging the voltage down from the 12.8 range to the 9.2 range. But once the engine is going the power circuitry is getting enough voltage/current from elsewhere to compensate.

I also need to get some larger gauge alligator clip/test wires, so I can see the current draw from the battery with ignition off and ignition on (no starting). Comparing the current draw difference between the two engines may give evidence to either short or a bad connection.

Might try to get a better amp tester . . . I might of fried mine during the testing so far.

 

[Lou C]

Could that be a sign of a parasitic draw?
I had to track one down on my old 98 Jeep. Turned out to be a rusty relay in the trailer tow harness..
I had a battery going flat after only about a week or 2 of not driving it and when I looked up my meter to this special Lisle harness made for checking for parasitic draws it pointed toward the trailer tow circuit, Just for the heck of it I checked the trailer lights and the ones on the driver side weren’t working. So I took off the interior panel where the trailer tow harness lives (that I installed like 24 years ago) and there it was a corroded relay….

 

[tpenfield]

Could that be a sign of a parasitic draw?
I had to track one down on my old 98 Jeep. Turned out to be a rusty relay in the trailer tow harness..

I did some current draw testing on the port and starboard batteries, but did not see anything of significance.

The boat's electrical system never sleeps (so it seems). There is the radio, the CO detector, the inverter, the mercathodes, and probably some other stuff that draw small amounts of current continuously.

 

[Lou C]

I think the spec on my old Jeep was 30-50 milliamps after all the modules power off. Many draws happen because a module is not powering off as it should.

 

[Scott Danforth]

Ted.... over 505 years old.... operates same as day it was built. (no electrics)

 

[Lou C]

Luddites get on board!

 

[muc]

Ted.... over 505 years old.View attachment 399022... operates same as day it was built. (no electrics)

Trouble is you need a crew to sail it ---and-----

As near as I can tell --- you can only drink grog

 

[muc]

View attachment 399013

Hey, I've got that same timing light. Customer bought it and gave it to me after he "moved" my much more expensive one so it got into the spinning belts. I felt that I was partially to blame, so I never said anything to him. But I did start enforcing a new rule ---- customers are allowed to watch but must stay at least 6' away at all times.

 

[muc]

Ted, I seem to remember the last go around with low voltage. But I can't remember if I saved all the files and notes. Can you post or PM your serial numbers? That's how I usually save that info. Also so can you post a link to that thread. If I remember right you stopped the troubleshooting process because new batts or something else seemed to fix it?
I'm pretty sure the relay buzzing is a low voltage issue.