20 amp wire harness fuse keeps blowing

[thimsllib]

I have a 1989 80 HP Merc. There is an inline 20 amp fuse in the wire harness on the motor. When I bought the motor, it only had a trim up solenoid. No trim down. So I put in a trim down solenoid and I think I wired everything up correctly, but the 20 amp fuse blows when I hit the trim switch on the throttle lever. I don't think it's wired incorrectly, but not 100% sure

Battery goes to starter solenoid.
jumps from starter solenoid to the trim up solenoid.
Jumps from trim up solenoid to trim down solenoid.
The red wire with the inline fuse is connected to the battery terminal on the trim up solenoid. Should that wire be connected somewhere else?

Thanks!

 

[achris]

Re: 20 amp wire harness fuse keeps blowing

Only blows on DOWN? Me thinks maybe bad winding in the trim motor...

Disconnect the big green wire on the bottom of the DOWN solenoid. If the fuse doesn't blow, it's the trim motor. If it still blows, then you gotta do some more troubleshooting...

Post results and we'll see what's up....

Chris......

 

[j_martin]

Re: 20 amp wire harness fuse keeps blowing

Only blows on DOWN? Me thinks maybe bad winding in the trim motor...

Disconnect the big green wire on the bottom of the DOWN solenoid. If the fuse doesn't blow, it's the trim motor. If it still blows, then you gotta do some more troubleshooting...

Post results and we'll see what's up....

Chris......

The trim motor shouldn't be pulling any power through that fuse. Only the solenoid coil current should go through it. You got it wired wrong, or there's an internal short on the "new" solenoid.

hope it helps
John

 

[achris]

Re: 20 amp wire harness fuse keeps blowing

The trim motor shouldn't be pulling any power through that fuse. Only the solenoid coil current should go through it. You got it wired wrong, or there's an internal short on the "new" solenoid.

hope it helps
John

Quite right. I realize after I posted, then went to edit and lost the internet connection...

 

[monk-monk]

Re: 20 amp wire harness fuse keeps blowing

Not so fast guys...it really depends on the style of wiring harness (coupled with the year model) as to where the TNT buttons gets power from: Early type A and type B systems used the power from the battery (at the posi battery terminal on the solenoids) to operate the TNT buttons...It is a "backfeed" circuit from the solenoids to the TNT buttons...Newer style wire harness' pull the power right from the Contoller Power Feed...then there is only two wires at the pump terminal wire harness connector..

 

[monk-monk]

Re: 20 amp wire harness fuse keeps blowing

You need to be looking at that down solenoid wiring. That 20 amp fuse is protecting the posi feed wire that runs inside the boat wire harness to the TNT buttons in the Controller. I would suggest checking your TNT buttons but it sounds like your trouble started by adding that down solenoid. And just where was the green wire (from the pump armature) hooked to previously...possibly to a little terminal block on the pump reservoir...?

 

[j_martin]

Re: 20 amp wire harness fuse keeps blowing

Not so fast guys...it really depends on the style of wiring harness (coupled with the year model) as to where the TNT buttons gets power from: Early type A and type B systems used the power from the battery (at the posi battery terminal on the solenoids) to operate the TNT buttons...It is a "backfeed" circuit from the solenoids to the TNT buttons...Newer style wire harness' pull the power right from the Contoller Power Feed...then there is only two wires at the pump terminal wire harness connector..

Either way, solenoid coil current is only an amp or so. Pump motor current doesn't come through that harness at all, but more or less directly from battery.
(Unless something's miswired or bad in the solenoid)

hope it helps
john

 

[thimsllib]

Re: 20 amp wire harness fuse keeps blowing

Thanks for all the responses guys. I really appreciate it. Here's where I am... Yesterday I went out and disconnected the red wire (with the inline fuse in it) from the posi bat terminal of the "up" solenoid and connected it to the posi bat terminal on the Starter solenoid. Well, the fuse doesn't blow anymore, but only the trim "down" works. Won't trim up and won't start.

On a side note, there's also another red wire going from the posi bat terminal on the "up" solenoid to what I think is a slave solenoid. It's a small square with 3 screws attached to the block under the starter solenoid. Does that sound right? Why isn't there also a wire going to the "down" solenoid?

I can't find any wiring diagrams on this. Can anyone explain how the 3 solenoids should be wired? Again, I appreciate your help. Thanks.

 

[achris]

Re: 20 amp wire harness fuse keeps blowing

 

[thimsllib]

Re: 20 amp wire harness fuse keeps blowing

AChris... thanks a million. This really helps. Right off the bat I think I have a ground issue. I'll post the results. Appreciate it!!