question about fuse in motor and power to console fuse block

[SierraMark]

I have recently redone the the wiring in boat as part of my restoration and now I am having a problem with the fuse on my trim and I'm thinking I did something wrong when re-wiring.

I think the original wiring maybe had 2 +12 runs to the fuse block but I am not positive.

This is what I currently have:

The motor is connected to the battery by 2 large wires...maybe 4 gauge? I did not modify those wires. As you can see in the image below the +12 goes from the battery to the starter solenoid then to a fuse. That fuse is 20A. The +12 then goes from the fuse into the cannon connector and up to the console.



What I've done is to put that +12 on the +12 of my new fuse block and then run everything off of fuses in there.

The first time I took the boat out I had a 15A fuse on the power trim and it blew. I came home and read on iBoats that the trim fuse should be 20A so I replaced the fuse with a 20A. Yesterday when I took the boat out I blew the 20A fuse in the motor.

So my question is this: I think there might have been a separate 30A inline fuse going from the battery to the console that I did not replace. Is that what I should be powering my fuse panel with? If that is the case then what is the 20A fused +12 coming out of the engine used for?

Yes, I also know that I need to figure out why my trim is blowing fuses, I think I know the reason and I'm working on that.

Thanks in advance for any help you can give.

-Mark

 

[Silvertip]

Re: question about fuse in motor and power to console fuse block

Motor fuse protects instruments and engine circuits only. Helm fuse panel is fed from a separate pair of #8 or #10 wires from battery. That circuit needs a 20 amp fuse. These are two rotally separate circuits.

 

[SierraMark]

Re: question about fuse in motor and power to console fuse block

Motor fuse protects instruments and engine circuits only. Helm fuse panel is fed from a separate pair of #8 or #10 wires from battery. That circuit needs a 20 amp fuse. These are two rotally separate circuits.

Silvertip,

Thanks for the response. I have a question, If the helm fuse panel is a 20 amp fuse then wouldn't a 30 amp fuse on the trim circuit be useless?

Thanks,
Mark

 

[Silvertip]

Re: question about fuse in motor and power to console fuse block

The trim circuit is part of the ENGINE system and should not be wired to the helm system.

 

[SierraMark]

Re: question about fuse in motor and power to console fuse block

The trim circuit is part of the ENGINE system and should not be wired to the helm system.

I don't quite understand. I have 2 trim switches, one on my engine and one on my throttle. The one on the throttle has 3 wires coming off of it, a red, a blue, and a green. They connect to +12 and the triim control. The red one is the one that I have fused and I've read that fuse should be 30 amp. When I had a 20 amp in there it kept blowing.

So are you saying that the red wire on my throttle goes to the red wire in the engine harness? That would mean I would blow the 20 amp fuse in the motor.

Sorry for my confusion, and thanks for your help.

Mark



-Mark

 

[Don S]

Re: question about fuse in motor and power to console fuse block

I don't quite understand. I have 2 trim switches, one on my engine and one on my throttle. The one on the throttle has 3 wires coming off of it, a red, a blue, and a green. They connect to +12 and the triim control. The red one is the one that I have fused and I've read that fuse should be 30 amp. When I had a 20 amp in there it kept blowing.

So are you saying that the red wire on my throttle goes to the red wire in the engine harness? That would mean I would blow the 20 amp fuse in the motor.

Post up a serial number and someone may come up with a service manual for your engine with a wiring diagram> Yes, the red wire on your trim handle gets power from the motor.

Going to move this over to the Merc outoard forum. Your problem is engine related not boat systems related.

 

[SierraMark]

Re: question about fuse in motor and power to console fuse block

Post up a serial number and someone may come up with a service manual for your engine with a wiring diagram> Yes, the red wire on your trim handle gets power from the motor.

Going to move this over to the Merc outoard forum. Your problem is engine related not boat systems related.

Serial Number is 0D036683.

I have 2 manuals, the Clymer and the one I found online. The online one seems to be way better.

This is the wiring diagram for the motor...


And this is the wiring diagram for the throttle...


From what the throttle diagram and what Silvertip has said the 12 volts to the throttle trim switch is wired into the red on the ignition and into the red on the motor wire harness, this is how I currently have it.

So my problem is that the trim blows the 20 amp fuse in the motor. I read on these forums that trim should be fused at 30 amps but that would mean changing the 20 amp fuse in the motor and I know it came like that so I wouldn't want to mess with it.

Thanks,
-Mark

 

[Silvertip]

Re: question about fuse in motor and power to console fuse block

Because you obtained this rig in a specific configuration does not mean it is "correctly" fitted, wired, fused, or whatever. Since you rewired, it is apparent this boat is not new so who knows what the prior owner(s) did. Fact is, if the engine mounted trim switch works fine with a 20 amp fuse then something you did at the helm when you "rewired" is causing the problem. The trim system is a stand-alone entity. It is energized from two sources. One of those sources is a 20 amp ENGINE circuit and it works fine. The other source is at the helm which is currently fused at 20 amps and it does not work fine. So the only thing one can point to is you mucked something up in the wiring. Besides, that control mounted trim switch should not even require any rewiring because it is part of the ENGINE harness to start with and is fully wired inside the control box and becomes part of the engine harness running between the box and the engine.