Trim fuse blowing at the helm.

[Philvtn]

92 Hurricane FD 23' I/O with 5.0 thunderbolt, alpha 2 g2. New motor this season (bathtubbed, lesson learned), mechanic installed. Got about 10 hours on the water. Was running home in rough weather, turns out my trim pump was running down for an extended time. Not clear why. Blew in the inline fuse at the pump. Replaced fuse, trailered up, 2 weeks later I went to launch again, no trim. Inline fuse is good, checked helm fuse block, 15A on a brown wire blown. Replaced, looked good, tried trim, nothing. Check fuses, the 15A blown again. Replaced, this time it blew instantly. Checked controls, checked wires at pump for damage, all looked good.. Swapped 20A, fried another instantly (I carry several spares lol). One more check through the connections then blew my backup 25A. Yea, I was being optimistic.. Briught it home.

So that's where I am. Pulled the fuse and battery, I've got a pretty low resistance short to ground from the cold side of that fuse. Switches have no affect on the reading. My hunch is the lower solenoid faulted, ran the pump down, toasted the inline fuse and roasted itself, and is now shorting. Not clear on how the brown wire plays in all of this. The solenoids and pump are in a terrible location, will be a huge pain pulling them. Any thoughts or suggestions for the likely culprit? It would help a ton to eliminate easier possibilities before I pull the solenoids.

 

[NYBo]

Never try to diagnose a short by using larger fuses! You could cause a fire. Do you have a wiring diagram for the motor? The fuse in the fuse panel may not have anything to do with the trim circuit. Anything else not working, like the bilge pump?

 

[Philvtn]

Don't have a general wiring diagram, wish I did. Most electrical was still working, though I can't say that I tested bilge, will try. I do have a diagram for the throttle controls, and I noted that there wasn't a brown wire described.. You might be right. To boot, I've had issues with the bilge pump recently and had to remove and replace it. It's manually switched though, and I never use it.

 

[Philvtn]

Alright, a little progress. NYBo you were right, brown wire and troublesome fuse are bilge. Checked wires for damage, new fuse, blew when I switched on bilge... Switch off, disconnected bilge pump, new fuse, blew instantly.. Yee haw, this one gonna be fun.

Back to trim, Testing at the control harness, continuity is good for all the trim switches. Ran a jumper to the up solenoid from battery pos, up trim works. Can't reach the down solenoid, so instead I jumped from battery pos to the trim wires (blue then green) at the controls (tried all switch positions too). Nothing for either.

Hate to add too much info, but my trim position sensor doesn't work, which it dawned on me may be the reason my up trim on the controls doesn't work, considering the switch just tested good lol. But from what I see on the diagram, the trim limiter should simply be open on the up wire, shouldn't affect down or the trailer switch.

 

[Philvtn]

Thinking about this, the reason I thought the trim pump ran for an extended time, is because one of my passengers heard a loud hum on the ride back to the ramp (at night, in a storm, couldn't locate the issue on the water).. Then at the ramp the inline fuse at the trim pump was blown.. Made an assumption there, but it could have been the bilge pump running making the noise, same location. I don't think the bilge switch was on at that time, but I can't say for certain. Now there's a short on that line, with the switch off.

I've made another unfounded assumption too, that the brown wire at the fuse box is in fact bilge. Still don't know that for certain, since it blew with the bilge disconnected.

 

[Philvtn]

Testing again.. At the controls, I get voltage on blue (up trim) with the switch. None on green (trim down), none on purple (which has a switch added for trailer up, fed from red). Trim up, and trailer up together, kills voltage on blue.

Testing continuity, there's a short on green(dwn) and purple(t.up), both switch positions. Open on blue(up).

Trying now to see if voltage is getting to the pump relays.

 

[Philvtn]

No Title

So I finally unmounted the trim pump.. Was able to get access to the bottom half of the relays. Jumped batt+ to the green(dwn) terminal, just throws sparks. Tested blue(up), seems to be working still. I don't see any damage to the wires. Have I found my issue? Is it likely the down relay is causing all this?

 

[Bondo]

Jumped batt+ to the green(dwn) terminal, just throws sparks. Tested blue(up), seems to be working still. I don't see any damage to the wires. Have I found my issue? Is it likely the down relay is causing all this?

Ayuh,.... Welcome Aboard,.... Sounds like the motor's the problem,....

Dead short on the down side,....

 

[Philvtn]

I meant the green terminal (trigger side) on the down relay threw sparks. That still mean a dead short on the motor?

Btw, I appreciated the response Bondo.