2005 24V ECM issue

[Teejay]

I bought this boat last May and it has performed flawlessly. Yesterday while towing the kids on a tube the motor just died. Then motor wouldn’t start. Got towed in.

Found a blown 15 AMP fuse (battery/ECM fuse) in the ECM. It actually melted the plastic of the fuse into the terminals. I clean it up best I could and stuck a few fuse in there. And she fired right up!

Should I maybe buy a new ECM assembly? I am thinking maybe there is something that caused the fuse to pop and this issue may happen again with or without a new ECM? Any help is appreciated.

Here are a few pics.16A468A3-FA27-41C2-BED0-4C5745832EF4.jpg7FAE2DC9-1B97-403F-876D-52B99A254601.jpgB096E500-B0DA-40C9-B0C8-F9853FACE268.jpg3B039D89-EFA8-4538-803A-534E4BE52D07.jpgADE35089-F22A-4748-95AD-B5239D25E15E.jpgB0BE2C4E-0886-498C-9D8D-C05BF9255E2F.jpg

[TeamAllen]

Somebody else might have a recommendation, but if I had anything related to the ECM I would contact these guys.
http://mefiburn.com/allinone.asp

[Teejay]

Spoke to Marine Power.

They said they had issues with these starting around 2011 or so.

They said this new wiring harness will fix the issue. $170. Might give it a shot

https://marineenginedepot.com/57l-81...ss-replacement

[IDBoating]

Fuses blow because of excessive current. That's their job.

Fuses MELT because... well, it shouldn't be possible. They should blow before excessive current raises the temperature enough to melt them and the socket they're in. Maaaaaaaybe if the current were juuuuuuuust below the threshold, and stayed there for a long time, the temperature could rise enough to melt plastic (not supposed to happen) while not blowing the fuse (designed specifically to happen).

In any case, I cannot see how a new wiring harness would fix this. If it's truly just a wiring harness, then all it has is wires and connectors. But your failure wasn't in a wire nor connector. So what can the new harness change?

* Make the wires and/or connectors larger to handle (even) more current. Hey, high current was the problem last time - why would this be better?

* Make the wires and/or connectors smaller, which means they would handle less current. At some point THEY become the fuse rather than the fuse itself, by having a lower current capacity than the fuse and blowing first. Again, why would this be an improvement?

I'd be reluctant to toss $170 at a new harness if the old one doesn't show any signs of damage, or if the manufacturer cannot explain why the new harness eliminates the fuse problem. There's an old adage about fuses: Just replacing a blown fuse doesn't solve the problem that caused the first one to blow, you need to understand and correct whatever caused the excessive current or it will likely happen again.

I'm going to contradict myself on that last point with two more ideas:

1) Maybe the blown fuse was the wrong value? Did someone install a far-too-high amperage fuse there? That might have allowed excessive current to flow long enough to raise the heat level.

2) Maybe the blown fuse was itself faulty? Perhaps the current went too high and the fuse either failed to blow or the metal failed in a way that shorted internally, allowing current to continue flowing.

Bottom line: Unless this new harness rewires something in a way that changes how the current flows, I don't see how that particular $170 will change anything. I'd be more inclined to confirm the proper fuse rating and buy reputable fuses.

Report back, this is an interesting problem!

EDIT: I'd also clean up the area on the solder side of the PCB around the melted connector. I would reflow the solder too, but you'll have to do that anyway when you replace the socket. The spacing between those traces is closer than I'd like to see, and I have seen cases where heat can reflow solder on the board and create a short - in which case current would flow whether the fuse were blown (or even present) or not. That, in turn, could give you some serious heat buildup. Make sure when you're done that there is clear, clean, exposed epoxy laminate between the pads for all of the fuse holders.

[sandm]

id, great synopsis.

wonder if the $170 includes a new circuit board and they have decided to only sell as a kit to either correct this/another deficiency or increased income vs selling a $5 circuit board. those traces are super close.

[lee]

I believe it removes the circuit board. It will have a harness where the relays plug right into the holders in the harness.

[chpthril]

Chicken before the egg: Did the fuse actually blow? Or did it just melt away? By the looks of it, i feel that there was poor conductivity between the fuse blades and the female terminals. This causing arching and excessive heat. This results in the melting and burned terminals.

With this said, I have seen fuel tank sending unit terminals do the same thing. the root cause was a long time failing of the in tank fuel pump drawing more and more current, yet never a spike that was enough to blow the fuse.

So what specifically does that fuse supply? id look close at that as the root, but yes, that board needs replaced/repaired as well.

[lee]

wire harness.jpg

Here is what the new one will look like installed.

[IDBoating]

Ah, so they are using the harness to REPLACE the printed circuit board. Nothing wrong with that. But where are the fuses? I see connectors to the relays (two of which look loose in that box and could bounce around, not good) but no sign of fuse protection. The photo of the harness also doesn't show any flying-lead fuse connectors.

[Teejay]

Lee, I got it in the mail today. Didn’t come with any instructions. I was stumped regarding where the 2 wires with spade connectors go. Also, which relays plug into the harness. The part #s on the relays plugged into the board have different part #s.

[Teejay]

There are three 15amp fuses in the blue/black weatherproof fuse block. It is just right of the original box in the photo.

[IDBoating]

I'm asking about the fuses which used to plug into the PCB that gets removed when the new harness is installed. Where do THOSE fuses now connect, since the PCB and its fuse sockets are gone?

[Teejay]

I'm asking about the fuses which used to plug into the PCB that gets removed when the new harness is installed. Where do THOSE fuses now connect, since the PCB and its fuse sockets are gone?

They are in a new little weatherproof fusebox. It is outside of the original square box. It is in a blue and black enclosure. You can see it in Lee's photo he posted.

[IDBoating]

They are in a new little weatherproof fusebox.

OK, got it. Thanks for the clarification!