Evinrude 150 xp 1990 trim switch blowing fuse.

[nano_b123]

Hey! Got this rinky dink, broken down boat a little while ago and put some serious work into it. I'm 16 so don't have the most experience but i've been restoring the 1989 Ranger for quite a while. It didn't run so I rebuilt the carbs, changed the fuel lines, rewired some of the boat, and installed bilges, livewell pumps and other appliances. I've been solving problems one by one but the only one troubling me is the trim switch at the front of the boat. I try to connect it to the extra trim wires from the control box and it works for a second then blows the in line fuse inside the engine. Not sure what to do. Can anyone help me? Would be much appreciated!

 

[brodmann]

I'm pretty sure that motor has plastic square relays just like the ones you would find in the fuse box of a car. I'd start by replacing those. Auto parts stores have them pretty cheap. The tilt/trim motor (pump) is just a reversible motor. So the relays are needed to basically reverse the wires going to the motor. Are there 2 or 3 wires coming out of the tilt/trim motor?

 

[brodmann]

Here's your wiring diagram for that motor tilt/trim

 

[nano_b123]

Awesome! Thanks for the response. Still blowing the fuse even though the original trim switch works.

 

[havoc_squad]

There is an easy way to narrow this down.

When you disconnect the trim wire plug (not the red harness plug) going to the boat, does the fuse blow when you use the trim switch on the bottom cowling of the outboard?

If it does, then the short is behind that trim plug for the trim relay wiring for the trim motor itself has a short or there is a short in one of the relays.

If you unplug the trim wires plug to the boat and it consistently does not blow the fuse using the lower cowl trim switch, I would suspect the trim wiring on the green or blue going to the control box or in the control box one of the trim wires is shorting to somewhere there is an electrical ground like on a control box or engine cowling.

If it was the red wire going to the boat trim switch, the fuse would blow immediately due to red wire is hot and short to ground without needing to press the switch.

This is a more accurate wiring diagram of trim system on that outboard model

https://maxrules.com/graphics/omc/wiring/TnT_87_UP.jpg

 

[brodmann]

Yeah, I was pretty sure that motor had 2 relays. My son recently had to replace the entire system on his 115 Johnson. The sockets for the relays were worn out and became very "iffy" only working sometimes. That first wiring diagram has a mistake. I've always told folks when working with tilt/trim motors to remember the sky is blue and the grass is green. The wire for "UP" on all tilt/trim systems I've worked on is blue and the "DOWN" wire has always been green "Grass". That's how I remember it. That first wiring diagram had that backwards.