1987 trim relays, do the stick on when they go?

I have a 1987 225 evinrude outboard and I am trouble shooting various small issues that have come up since the intallation. I have rebuilt eveything, and recently installed it on my boat. I have also spliced in the evinrude wiring harness into the force harness that was in the boat.

The issue I am having is where I activate the trim switch on the dash "up" it works perfect. When I push down it works, but does not shut off. I am just sitting here thinking that the relay might be sticking. The switch is a mechanical momentary "up-on and down-on". So it is disenguaging. No power is flowing to and from the switch when I test. Could the relay be bad?

DO these relay some times stick when activated?

I am going to swap (Up for Down) the relays tonight and see if it happens in the reverse situation and sticks.

Re: 1987 trim relays, do the stick on when they go?

I've never seen one lock in the points closed position, it's always been a faulty PTT switch.

However you state "No power is flowing to and from the switch when I test." meaning to me that you have disconnected the voltage that normally leads to the PTT switch. If so, the relay would need to be sticking in order to stay engaged.

Re: 1987 trim relays, do the stick on when they go?

There's another possibility. In control systems there are times when you want a relay to stay energized with just a momentary pushbutton, there's a way to wire them to do that where you use power from one of the contacts to keep the coil energized. There's a slim slim possibility this is happening to you (through messed up wiring), depending on what you find out after swapping relays.

How do you "unstick" the down relay? If it's just a matter of disconnecting power I'd say there's something more going on than a stuck contact.

Also, are you absolutely positive there's no power coming off the down switch contact, in other words are you certain the switch isn't sticking?

One more thing, is the Force control box in you boat wired the same for up and down trim as an OMC?

Re: 1987 trim relays, do the stick on when they go?

relay contacts can get stuck. it is a very weak spring so that a small electromagnet can pull the points open and closed. If gummy residue gets inside or if the spring breaks then it can stick. However, that is rare.

If you think it is a relay then just replace it. Trim relays are only $3 each off ebay. Search for mercury, force, volvo. they use same kind. the little cube relay with five flat prongs is a universal standard. If it looks like one then it IS one.

more likely it is a short in the wiring. people tend to know its a bad switch because they used to jiggle the switch and get it to work.

Update

Update

Well this is going to sound strange but it fixed it self.

Started off the night trouble shooting this one. I started but turning on the main bus power (perko switch). Test no power on the down line, but power on the in (feed) line on both switchs (transom and dash). Active the dash switch up, motor moves up, and stops when disengauged. Push dash switch down, and motor moves down, but keeps going after I let go on switch. I unplug the connection to the trim motor and start check where the power is coming from....

Unhook power feed wire at both switches and the test light is still showing power in the down line. Strange but ture. So I pull the relays and the swap them. When the relays are removed the power is not lost in the down wire. I go and swap the relays and the other does the same thing (activates). So my thinking is that I have some wrong wire hooked up somewhere.

So I start under the dash and follow the down wire back to where the main harness coating is cut back. I cut a few zip ties holing the wire bundle together neetly. Everything checks out. No other wire hooked into it under the dash.

Next I do the same tracing at the motor. Everything is hooked up as it is required by the Evinrude service manual at the trim box.

While this is going on I still check for power on that down wire and it is there.

I start cutting the marine heat shrink off the harness patch. That was a fun thing to do. When I finally get the heat shrink and glue off and cleaned up I go to check for the hot wire effect and its gone. SO I go and hook up the dash switch and nothing, No power in down wire. I go and hook up the transom switch and still no power. SO I hook up the trim pump motor connector. And it works great.

No issue. I did not change any wires, did not change anything other than cut the heat shrink off the wire harness. So I electrical tape the harness back up and cleaned everything up but under the dash. Still need to install two guages in the dash.

The switches and the motor work great! The relay does not stick anymore. I'm going to go wqith it. If I have an issue out on the water I and just disconnect the wire connect to the trim motor and jump the wires to get the motor trimed to where I wanted.

Anyone ever hear of this happening before?

Re: Update

Re: Update

The last thing you did, and I quote "I start cutting the marine heat shrink off the harness patch. That was a fun thing to do. When I finally get the heat shrink and glue off and cleaned up I go to check for the hot wire effect and its gone."

It's unlikely the problem fixed itself but rather that you distrubed the problem area, breaking the circuit, at what you call a harness patch. I strongly suspect that within that patch there is a small unprotected access point to voltage along with the same access to the blue PTT down mode lead.

A short does not need to be a wire to wire contact, it can be a conductive type short, a voltage radiation thru flawed insulation to another or via moisture. Should the problem pop up again, this may be something to keep in mind.

Re: Update

Re: Update

I've designed, modified, and repaird industrial control systems for over 20 years so I've seen my share of mysterious electrical "stuff". But as Joe said, electrical problems don't repair themselves. Sooner or later it'll come back to bite you.

Re: Update

Re: Update

I'm sure it will and at the worst time no doubt. But short (pun intended) of replacing the whole wire front to back, there is not much to check. Anyone ever here of marine heat shrink conductin electricity?

My other thought is that the short was up under the dash. I have not finished up under there. The wire could have been worn against a screw or something.
Well it will be easier I did not see anything that indicated this condition but when I install the two guage this afternoon I keep a close eye out for this.

Well untill it shows up I can not find what is not there.

Re: Update

Re: Update

usually the control relay post is like #86 or something and the relay output is #30. My guess would have been a short between these two wires. Once activated the positive output shorts back onto the control wire and keeps itself connected. that type of short would usually be within a few inches of the relay itself.