Power Trim on Merc 115 OB

[elad]

Could someone help me diagnose what's wrong with the power trim unit on my Merc 115 OB?

The last time I used the boat everything worked great. Now, a couple months later, the power trim won't work. All I get is a single "click" in the engine area right close to where the fuse for the trim unit is. That click is the same for trim up or down. Is there a relay or something there? Could that be the problem?

Right now the engine is trimmed up just a little. I'm nervous about letting it down manually because I think it'll hit the garage floor and I don't think I'll be able to get it back up again without a jack. Will I have to eventually let it all the way down manually in order to then raise it high enough to work on the trim motor?

If the problem turns out to be the trim motor, could someone walk me through the process of replacing it?

 

[Laddies]

Re: Power Trim on Merc 115 OB

WE need to know the year of type of trim you have, you don't have to worry about releasing the trim with it release you can move it from full up to full down it will move either way. if the trim clicks both ways it's probably the motor if it runs one way and not the other it's probably a solenoid

 

[elad]

Re: Power Trim on Merc 115 OB

Hey Laddies, thanks for the quick reply.

It's a 1990 Merc 115. I've been looking over the paperwork and can't find where it says what "type" of trim it is. It was the original equipment. Is there something I can look for to help determine what you're looking for? Maybe the engines serial # or something?

Dale

 

[Laddies]

Re: Power Trim on Merc 115 OB

That's close enough, start by removing the cowl and the electrical cover, if the motor runs one way ck the solonoids with a voltmeter 1 has a small blue wire to activate it thats the up solinoid the 1 with a green lead is for down and the other one has a yellow/red wire is for the engine starter. Get back after that with the results and we will can tell you what the problem is. Let me warn you that the pump motor is not easy to change if thats the problem

 

[elad]

Re: Power Trim on Merc 115 OB

The trim/tilt motor doesn't run either way. Just a click whether I try to run it up or down. Is it the same solenoid for the trim motor as it is for the engine starter? Since the trim motor doesn't run either way, but the engine starter works fine, is it still possible it could be a solenoid problem? I don't have a volt meter, but, if it's necessary to troubleshoot this, I'll get one.

Thanks again for your help!

 

[Laddies]

Re: Power Trim on Merc 115 OB

It's always nice to have a meter but you can do this test without one, once you have found the solenoids simply use a screwdriver and short across the 2 large terminals and the pump should run(use a older screwdriver as it may arc a little) I belive from what you tell me the motor is bad and you probably won't see a arc or anything when the brushes wear out there is not a circuit so nothing happens at all. If you decide to try to change the motor you will need to get a OEM manual. I can PM the page out of one if you want but as you can see they really buried the motor in the motor bracket.

 

[elad]

Re: Power Trim on Merc 115 OB

If you click on the photo it will enlarge. Hit back button to come back here (I learned the hard way and closed by browser).

In above photo, I've circled what I believe you're saying are the solenoids. I tried jumping with a screw driver on the top two solenoids . . . nothing! on either one. Not even the "click" I get when I use the switch. You are saying to jump across the two posts with the nuts, right?

I'm assuming the reason it wouldn't jump for the starter solenoid is because I didn't have the key in the "on" position, right?

 

[Laddies]

Re: Power Trim on Merc 115 OB

The top solenoid is up, the middle is down and the bottom is starter if you jump from large lug to large lug the solenoid won't click as you have bypassed their function but if you jumped the bottom and the engine didn't turn over(as it should) You may have a bad connection some where is the engine should turn when those 2 are jumped.

 

[elad]

Re: Power Trim on Merc 115 OB

The top solenoid is up, the middle is down and the bottom is starter if you jump from large lug to large lug the solenoid won't click as you have bypassed their function but if you jumped the bottom and the engine didn't turn over(as it should) You may have a bad connection some where is the engine should turn when those 2 are jumped.

OK, I got it to turn over by jumping it. Not sure why it didn't work before. Maybe I didn't make the connection I thought I was making.

It still doesn't do anything when jumping the trim solenoids though. I found what may be the problem. There's some wear on the wiring harness for the 3 wires that go to the two trim solenoids. I think it's only 3. . . Green, Blue, and Black. It's the same one that crosses over the thick Yellow wire leading to the starter, in the photo. Is there a way to bypass those incoming wires to see if that's where the problem is? Or did I already do that when I jumped it?

Wait! Those aren't incoming, are they? They're outgoing, leading to the trim motor. I bet that's the problem.

 

[elad]

Re: Power Trim on Merc 115 OB

Took the wiring harness off so I could unravel it, then reinstalled it for testing. Still not having any success.

Bottom line is: If there's no power coming from the solenoid after jumping it, then it doesn't matter what shape that wiring harness is in because the power never gets to it anyway, eh?

Although I re-read what you said about there not being any current if the brushes are worn out so it appears I still don't understand.

I gotta get a volt meter. When I do, do I check the same two posts just like when I jumped it?

BTW, sorry for taking so much of your time. I see most people have their problem resolved in just a few posts.

 

[MercFan]

Re: Power Trim on Merc 115 OB

My engine and power trim is much older than yours, but when my solinoids clicked and I got no response from the trim motor it was simply worn brushes in the motor. Replaced the brushes, no problem since.

If you measure power with a multi meter, is the power getting to your trim motor? That's the route I'd take. Follow the power and measure at various points down stream. For a system like that the circuit "should" be very simple. Battery to solinoids to trim motor. With your trim switch teeing into the circuit at the solinoids. If you're getting the solinoids to click when you use the trim switch atleast you know the tee part of the circuit is working. So all you need to establish is if the power is avalable at the solinoid's one side, and then when you use the trim switch, does the power flow through the solinoid to the motor? If it does, does the power actually get to the motor? If it does, the problem is inside the motor and then probably brushes, or maybe something is preventing the pump shaft from turning. It could even be something as simple as a bad eath at the trim motor. Remeber that you need both 12V+ and a earth to actually have power. But only the 12V+ gets broken by the solinoid switch. The earth is uninterrupted. So you can use your multimeter's resistance or continuity setting to double check your trim motor earth to battery negative.

 

[elad]

Re: Power Trim on Merc 115 OB

Thanks for the input MercFan.

I don't have a voltmeter, but someone suggested I try jumping power from the starter solenoid. I'm going to try that and see what shakes out.

 

[elad]

Re: Power Trim on Merc 115 OB

OK, I did the jump from the starter solenoid . . . Nothing, on either wire. If I understand you Laddies, your saying is about 99.9% the trim motor, with a minuscule chance that it's a ground wire?

That page from the OEM manual starting to look good.

BTW, I did another little test by disconnecting both hot connections to the trim solenoids. When operating the switch to trim the engine, I still get a click. Apparently the click is coming from something other than the solenoids?

 

[Laddies]

Re: Power Trim on Merc 115 OB

The solenoid will click as they are energized from he 12 volt feed from the front trim switch that gets it power the same source that the key switch does but with no power hooked to them, they the click but do nothing

 

[elad]

Re: Power Trim on Merc 115 OB

The solenoid will click as they are energized from he 12 volt feed from the front trim switch that gets it power the same source that the key switch does but with no power hooked to them, they the click but do nothing

Oh, OK. So you think it's the trim motor then, eh? Got a good part supplier and a page from the OEM Manual? I'd appreciate it.

 

[MercFan]

Re: Power Trim on Merc 115 OB

have you confirmed that your "hot" wires are indeed hot? do you have twelve volts on one side of each solenoid?

 

[elad]

Re: Power Trim on Merc 115 OB

have you confirmed that your "hot" wires are indeed hot? do you have twelve volts on one side of each solenoid?

I know the starter solenoid is hot because it turns over the engine. By connecting either one of the trim wires to that hot terminal I know it's getting the current. But because the trim motor doesn't run, it's just not completing it. I'm assuming that's because the trim motor is burnt not making the circuit.

Make sense to you?

 

[MercFan]

Re: Power Trim on Merc 115 OB

Yep, I'd check the brushes next.

 

[elad]

Re: Power Trim on Merc 115 OB

Yep, I'd check the brushes next.

Yeah, I don't know how to do brushes though. So, I guess I'm looking for a new (or rebuilt) motor. Unless someone can convince me it's not too hard to do myself.

 

[MercFan]

Re: Power Trim on Merc 115 OB

Very easy. If I remember correctly you remove 2 screws and pop-off the cover at the end of the motor. The brushes are right there. Just pull the retaining springs back, slide out the brush, slide in the new brush and you're basically done. I think the copper wire that comes attached to the brush is also just screwed onto a terminal right there.

If you don't want to try it yourself, just take it to an auto electrician to do it for you.