1986 starcraft 170hp mercruiser.

[BobLeeSwagger380]

Can someone help me find a wiring diagram? I just bought this boat and the trim sensors are not hooked up and I can't find any info on where the wires go. TIA!

 

[matt167]

They are not hooked up because they rarely work and don’t really need to. Big pain. They go to the trim senders on the gimbal pins. Generally make them work during a bellows or gimble bearing service

 

[BobLeeSwagger380]

Ok thanks. Can you tell me why there are 2 trim switches? One on the dash and one on the handle. The one on the dash works in the up position and the one on the handle works in the down position.

 

[matt167]

Not really sure. The ones on the dashboard may be added or it’s for trailer position. Likely working like that due to trim senders not working

 

[nola mike]

Ok thanks. Can you tell me why there are 2 trim switches? One on the dash and one on the handle. The one on the dash works in the up position and the one on the handle works in the down position.

Probably as a workaround for a bad trim limit sensor. In that case, the "up" trim button doesn't work but down does, and the trailer button works to raise the drive. If that button doesn't work, there was probably a bad switch and a bad sensor, and this was somebody's solution.

 

[Scott06]

Ok thanks. Can you tell me why there are 2 trim switches? One on the dash and one on the handle. The one on the dash works in the up position and the one on the handle works in the down position.

What year is your boat. Older mc-1 had three buttons on the dash. Later ones (my ‘90 alpa one did) had them on shift lever. Suspect someone repowered or added a newer shift lever… may take a little looking around to see whats hooked up …or what someone did…

 

[matt167]

He says 86 which should not have buttons on the dash. They would be on the lever

 

[BobLeeSwagger380]

What year is your boat. Older mc-1 had three buttons on the dash. Later ones (my ‘90 alpa one did) had them on shift lever. Suspect someone repowered or added a newer shift lever… may take a little looking around to see whats hooked up …or what someone did…

 

[matt167]

Looks like a shortcut button for trailer position added by boat mfr. I think one of my dads boats had that like that. It was an 83 imperial with a 470. That switch always worked but sometimes had to cross the relay to lower the drive. He never fixed as the 470 blew a gasket before he had the chance to inspect the switches

 

[BobLeeSwagger380]

Whats the difference from trailer position and trim all the way up?

 

[Scott06]

Whats the difference from trailer position and trim all the way up?

Trim up only lifts the drive about halfway up. This is the limit of trim you can use during running at speed. Trailer button is used to get all the way up engine shouldn’t be used more than just above idle rpm when in trailer .
there is a limit switch on port side of outdrive that limits how far up trim will work, trailer will always work… your limit isnt hooked up to trim pump so only trailer button works for up . Trim down is only down button . So need to figure out where your limit switch should hook up, which is what you were trying to do… will try and dig up a wiring digram, should be able to jumper out limit to test trim up…

found this one and added it i think basically what You have . That will show where to land trim limit. Sender off starboard side of drive goes into engine harness to make its way to dash and trim guage

 

[BobLeeSwagger380]

Trim up only lifts the drive about halfway up. This is the limit of trim you can use during running at speed. Trailer button is used to get all the way up engine shouldn’t be used more than just above idle rpm when in trailer .
there is a limit switch on port side of outdrive that limits how far up trim will work, trailer will always work… your limit isnt hooked up to trim pump so only trailer button works for up . Trim down is only down button . So need to figure out where your limit switch should hook up, which is what you were trying to do… will try and dig up a wiring digram, should be able to jumper out limit to test trim up…

found this one and added it i think basically what You have . That will show where to land trim limit. Sender off starboard side of drive goes into engine harness to make its way to dash and trim guage

I found that same diagram but didn't think it was the right one. What you are saying makes better sense to me now. I still don't understand where these dam wires go.

 

[BobLeeSwagger380]

I found that same diagram but didn't think it was the right one. What you are saying makes better sense to me now. I still don't understand where these dam wires go. View attachment 371057

The lower wires specifically. One is ground and one is power.

 

[BobLeeSwagger380]

The lower wires specifically. One is ground and one is power.

Do these blue-white and purple-white wires go to the trailer switch?

 

[nola mike]

Trim down switch: connects grn/wht to red/purple
Trim up switch: connects p/w to r/p. If switch is closed (motor down) p/w connects to blu/wht
Trailer switch: connects r/p to b/w, bypassing limit switch

Red/purple is hot. If the blu/wht wire is hot, motor goes up. Grn/wht hot lowers drive

 

[BobLeeSwagger380]

Trim down switch: connects grn/wht to red/purple
Trim up switch: connects p/w to r/p. If switch is closed (motor down) p/w connects to blu/wht
Trailer switch: connects r/p to b/w, bypassing limit switch

Red/purple is hot. If the blu/wht wire is hot, motor goes up. Grn/wht hot lowers drive

Thank you I will give that a try.

 

[BobLeeSwagger380]

Trim up and down and tilt up is all working properly now. I need to adjust the trim switch so I can bring it up more I think bit idk so any input on where it needs to be would be great. Also I am still not sure where the trim guage sensor is supposed to wire into. I still have 2 old wires sitting there that come from ground and power by the circuit breaker but I dont think that's where it hooks up. Going to throw some fuel in this beast tomorrow and see what she does. I popped the oil fill cap off the valve cover and saw rust on the rocker arms so that kinda sucks and I filled the cooling system last week and now it's empty. No water on the dipstick so that's good.

 

[BobLeeSwagger380]

Shouldn't I see water coming out of somewhere when I have the muffs on and the engine started or even when the engine is off.

 

[nola mike]

Shouldn't I see water coming out of somewhere when I have the muffs on and the engine started or even when the engine is off.

Not when it's off, but running should come out of the relief ports on the transom and/or the prop. Might take 30-60 seconds to fill.

 

[ROY WILLIAMS]

Can someone help me find a wiring diagram? I just bought this boat and the trim sensors are not hooked up and I can't find any info on where the wires go. TIA!View attachment 371022

the wires are corroded and the out drive switch is not working.
the owner shorted out in the back of the engine .bypassed it ..