Mercury Trim Switch on Throttle Only Goes Up

[Frsmith2]

I have a 50 hp Mercury 2 Stroke with power trim (up/down). There's a switch on my throttle handle and one on the motor. The switch on the throttle handle is now only working when I bring it up, no longer down. However the switch on the motor works in both up/down. I replaced the switch and same issue. Looking at the wiring in the console nothing looks out of place. I suspect the issue is somewhere near the motor, just don't know if there's something given the symptoms I should be looking for? Thanks.

 

[BigDog98]

Most likely a bad solenoid

 

[glenn property of pam]

follow the wiring from the switch on the side. It should go to a box. The switch from the throttle is going to the same box via a plug. The best test is to open the box and test the wires with a volt meter (instructions for using a volt meter are at the top of the electrical forum under stickys). The switchs are normally connected in parallel. If one switch works and the other only works in one direction then you can presume that its a bad connection/broken wire as you have already changed the switch. If I had to guess I would go with a bad connection probably in a plug. A volt meter is your best friend when it comes to finding the problem.

 

[Frsmith2]

Thanks...so, did a quick swap today of the two relays (up/down) that the combined wires go into before the blue and green head to the motor. No change. All connections where they combine before headed to relay and motor still look nice and sealed and crimped right. I know the volt meter should help me start to work my way to the issue, but a wiring schematic would be very helpful if anyone has. I see a lot on the web but not all apply. This is on a 2005 Mercury Elpto 50 hp 2 Stroke with an up/down switch on the controller and an up/down switch on the motor. Motor switch works fine, only getting up on the controller switch.

 

[Frsmith2]

Thanks...so, did a quick swap today of the two relays (up/down) that the combined wires go into before the blue and green head to the motor. No change. All connections where they combine before headed to relay and motor still look nice and sealed and crimped right. I know the volt meter should help me start to work my way to the issue, but a wiring schematic would be very helpful if anyone has. I see a lot on the web but not all apply. This is on a 2005 Mercury Elpto 50 hp 2 Stroke with an up/down switch on the controller and an up/down switch on the motor. Motor switch works fine, only getting up on the controller switch.

 

[sam am I]

First, do both relay's click in turn when the throttle switch is moved into the appropriate positions? (Probably not since both have to be working w the cowl switch not having an issue) Assuming not then and just the "up" clicking and w a new switch at throttle w no change. Also swapped relay's(wasn't necessary due to cowl/motor switch telling you they both were good), no change......Sounds like there is an open wire between the throttle switch and the down relay eh?

Try this to confirm my guess..... With power OFF and everything back together/in place(relays, connectors and such), open up the throttle to get at the T/T switch again, should be a blue wire and a green wire attached to the switch. Using an ohm meter w one lead connected to a known good ground(engine block/batt. neg. post preferably) and w/o pressing the(any) switch, measure both the blue and green wires(leaving them connected to the switch is fine). The blue reading should match the green reading pretty closely(around 100 ohms if I recall right). My guess is that the green reading will be waaaaaay high/open.

Sry no print on that new of engine here, I run ooooold stuff, BUT the good news is new or old, the T/T's are still all fairly simple and have stayed pretty much the same over the yrs.

 

[Frsmith2]

Thanks, Sam. I'll give it a go and report back. Just looking at the condition of the wiring and this being a random fail, I can't logically find where a green wire would just "open" but stranger things have happened!

 

[sam am I]

Or maybe the/a circular 8 pin engine connector pin is corroded up? Did you unplug that and re-plug it a few times? That would cause an open in that path too.

And yw and I sorta was thinking about that same thing later on last night. Best I could envision then would be the wire stands are subtly broken inside the insulation where the wire would perhaps be rotating about a pivot point at some radius as it routes through the throttle assembly .......

Also, as its been described working at the cowl and not working at the throttle and what has been replaced/swapped around, I'm at a loss at this point as what else could possibly be wrong. That green path to the down relay from the toggle has had to of opened somewhere.......Unless I'm overlooking(I often lose sight of the forest through all the trees) something obvious, its the only logical thing left....I think!!

Ohm meter test on the switch tho should make for a quick and easy way of telling us which way to go

Plz do let us know what ya find, tyvm.

 

[sam am I]

It'll sure be nice when this double posting POS finally gets fixed....geeesh.

 

[Frsmith2]

So, found the issue. I checked every green wire coming from the switch and into the hard plastic/rubber harness that exited through the floor. All good. Checked the green wire coming out of the harness at the motor that connected via waterproof connectors to the switch on the motor. All looked perfect, no breaks or corrosion. I then got under the boat and began to chase the harness - thinking, how could hard plastic/rubber create a break? Well...something in the water was hungry. Literally chewed through the harness until it broke its first wire and moved on...the green one.

 

[sam am I]

Hmmmm, keep your toes out of the water sounds........ Glad ya got it and thx for the follow up