225 sho blowing fuse. help please

[TownsendsFJR1300]

Sounds like Rodbolt has it pretty much narrowed down ...

[99yam40]

Only thing I can see is the ECU may be grounding a lead when it should not be if every thing else does not show a problem.
but we will have to wait

[walleye1]

I'd bet more on the motor being bad than the ecu.

[99yam40]

again he has said the disconnection of the motor does not stop the fuse from blowing

[HarrisonDawgs]

Rodbolt,, please give me an opinion. I have checked about all I can. With ETV harness disconnected, fuse still blows. This means it is not the ETV motor, correct? Also, when I disconnect the largest ECM harness (top plug A) and leave everything else connected, fuse does not blow. If I pull the 10 amp fuse, power up the start button and wait until I hear the fuel pumps stop and then plug the ETV fuse in the slot with key still on, it does not blow, so...fuse is only blowing in first 10 seconds of start up sequence. I am very curious with this scenario where you think the problem is. I have come to the conclusion it must be in the ECM, which leads to my final question...Lets assume I had a loose battery ground wire (wing nut not fully tight). I noticed a power stall each time I touched the trim button in either direction. This happened 3 times before the final trim which resulted in loss of accelerator (likely blew the fuse). Is there a possibility that a heavy amp pull from the trim along with the loose ground cable on the battery could have caused a short in the ECM? Reason I am asking is because I am leaning toward replacing the ECM (relatively inexpensive) and I believe you are right about YDIS not diagnosing this given the conditions I am seeing. If the ECM can be damaged by a loose ground cable then it might be a safe gamble to replace ECM and tighten down everything securely, but I would hate to destroy a new ECM if that is not the problem. I truly respect your opinions and advice and appreciate your help. It will likely head to the shop on Friday as this is my last stab at it.

[HarrisonDawgs]

Perhaps there is hope for YDIS. Just noticed trouble code 121 for ET system malfunction says replace the ECM.

[fairdeal]

I am leaning toward replacing the ECM (relatively inexpensive) .

(insert pulsating eyeball-popping emoticon here)

[panasonic]

Do you know anyone with the same engine as yours? You could put your ECM on thier engine see if it does the same thing. Worst that can happen is you blow a fuse on their engine.

I still think you got short in your harness.

Does the trim wiring run in the same wire bundle as the EVT wires? Seems if this started when you had the trim problem, that would be a clue.

[fairdeal]

I've said it before and checked it quadruple times...no shorts in wires (pin to pin at harnesses).

I'm guilty of not reading most of the thread since it started -

so apologies if your methodology has already been discussed - and I may be misinterpreting what you are describing


but I would not be looking "pin to pin" - I would be looking for presence of continuity "pin to ground" where there should be none

[walleye1]

What if you checked short to ground at the fues holder and at the same pin at the ecm? Just throwing it out there.

[dray0151]

If and when you get this fixed I would get rid real fast of the wing nits you mention. Use regular bolt nuts much better to tighten and stay that way with a lock washer. From reading I would too suspect a short to a ground somewhere.

[HarrisonDawgs]

I'm guilty of not reading most of the thread since it started -

so apologies if your methodology has already been discussed - and I may be misinterpreting what you are describing


but I would not be looking "pin to pin" - I would be looking for presence of continuity "pin to ground" where there should be none

Gotcha. But, yes, I've done that also. I will likely go thru the whole process one more time and I have cleaned, organized and checked so much. Doubt anything has changed but might as well try once more before it goes to shop. One problem I have not mentioned is that the dealer I have used in the past is now out of business and good technician/mechanics are sometimes hard to find.

[TownsendsFJR1300]

If and when you get this fixed I would get rid real fast of the wing nits you mention. Use regular bolt nuts much better to tighten and stay that way with a lock washer. From reading I would too suspect a short to a ground somewhere.

Better yet, self locking SS nuts (with the nylon) AND a SS lock washer with dielectric grease..

[HarrisonDawgs]

Better yet, self locking SS nuts (with the nylon) AND a SS lock washer with dielectric grease..

Yep. believe it or not all 3 tm batteries have nuts and I carry adj wrench in boat. This battery was relatively new and I was in a hurry to use it hence the wing nuts and I never got around to replacing them. I did notice on the s2nd or 3rd try to swap batteries that the negative cable was loose and nut felt tight but...it was 26 degrees when I was attempting this. Not actually sure it was loose when the problem started but I know at one point I realized it felt tight but was not.

[rodbolt17]

use the Yamaha dealer locator. find a shop with a master tech.