Need help fixing Trim UP function and identifying switch use!

I've taken on a 1993 Maxum 1700SR boat restoration project and am sorting out the wiring. Surprisingly all the electrics work except for the radio and trim up control. Has a I/O Merc 3.0 Alpha 1

The "trailer" button on the throttle arm works fine, and of the "up/down" trim selector on the throttle handle, only the "down" works.. and that is after probably a two second delay of holding the switch. The UP side doesn't work at all even if I hold it in, but like I said the trailer button brings the drive up. So...do I have a switch problem? Or is it a relay/solenoid problem at the trim pump? Does the UP button use the same relay/solenoid as the trailer button, or does the UP button share a reversable relay/solenoid with the DOWN button to move the drive at a slower speed (i.e. to trim). I'm pretty savvy w an OHM meter and test light, so what procedures do you recc'd to figure out whats wrong? Thanks a lot.. Also--I'm not implying that it has both a relay and a solenoid...I just don't know which it has...



Are these wires in the next pic for the trim gauge, because it works fine btw...

Re: Need help fixing Trim UP function and identifying switch use!

Below is a .pdf file that covers troubleshooting of your trim system with wiring diagrams.
Should lead you right to the problem.

Re: Need help fixing Trim UP function and identifying switch use!

rpaldrich said:

do I have a switch problem?
Or is it a relay/solenoid problem at the trim pump?
Does the UP button use the same relay/solenoid as the trailer button,

Click to expand...

Probably not, but will find out.
No (with up anyway)
Yes

More likely that the trim limit switch (on outdrive) is the problem. Easy to check. Back near the transom, locate two black wires (from limit switch) that go into two connectors, one with a with a purple/white wire and one with two blue/white wires. Unplug the black wires, and jumper between the connectors. Try the switch. If it works your trouble is in the trim limit switch circuit. Either the TL switch or wires is bad.

Re: Need help fixing Trim UP function and identifying switch use!

FYI the red wire is the hot wire going to your switchs.The blue is the hot wire coming back from the switchs for up.The green is the hot wire coming back from the switchs for down. The heavy red wire connected to the breaker at the pump is hot coming from the battery. Blacks will be grounds.

Re: Need help fixing Trim UP function and identifying switch use!

stonyloam said:

More likely that the trim limit switch (on outdrive) is the problem. Easy to check. Back near the transom, locate two black wires (from limit switch) that go into two connectors, one with a with a purple/white wire and one with two blue/white wires. Unplug the black wires, and jumper between the connectors. Try the switch. If it works your trouble is in the trim limit switch circuit. Either the TL switch or wires is bad.

Click to expand...

And that covers about 99.9% of "my UP switch doesn't work"....

Just make sure you get the right pair of blacks. One pair is for the gauge and the other pair is for the switch. The gauge ones got to a ground (Black) and a Brown/white wire....

Re: Need help fixing Trim UP function and identifying switch use!

picklenjim said:

FYI the red wire is the hot wire going to your switchs.The blue is the hot wire coming back from the switchs for up.The green is the hot wire coming back from the switchs for down. The heavy red wire connected to the breaker at the pump is hot coming from the battery. Blacks will be grounds.

Click to expand...

The green and blue wires are NOT hot, they are switched....

Re: Need help fixing Trim UP function and identifying switch use!

achris said:

The green and blue wires are NOT hot, they are switched....

Click to expand...

As I said, the blue and green are the hot wires coming back from the switchs. Obviously they are only hot when the switch is applied.

Re: Need help fixing Trim UP function and identifying switch use!

Blue is "UP", just so he knows which should do what.

Re: Need help fixing Trim UP function and identifying switch use!

You know you have power to the switch, so don't mess with the control handle until you jumper that the connectors to isolate the problem.

Re: Need help fixing Trim UP function and identifying switch use!

Thanks for all the help.. In fact it was a couple of problems. First, the trim limit switch is bad but the previous owner had already jumpered the wires to let the trim switch still work, and it had no continuity in the down position. He just bypassed it.

After figuring that out, I had then decided it was a bad switch because of this:

picklenjim said:

FYI the red wire is the hot wire going to your switchs.The blue is the hot wire coming back from the switchs for up.The green is the hot wire coming back from the switchs for down. The heavy red wire connected to the breaker at the pump is hot coming from the battery. Blacks will be grounds.

Click to expand...

The blue/white wire coming from the trim pump to the trim limit switch does transmit the power from both the up trim and trailer buttons...but the blue/white wire that continues on from the limit switch to the throttle handle is only for the trailer button. The Purple/white wire coming from the throttle handle to the trim limit switch is the one you need to test for 12v on when button is clicked up if your trailer button works, but up trim button doesn't. If you look at the diagram in the second post above, you can see that this allows the trailer switch to bypass the trim limit switch... the PURPLE wire is the switched wire connected to the trim switch, and I found a continuity problem in the wire. The PO had for some reason an extension spliced into the trim wires (maybe he wanted dual control of it at the transom) and the connection was bad. Anyway problem solved. All switches work.

Trim limit switch? I've heard replacement is a pain, and if its the only thing wrong... My gauge works, any problem with just using it to prevent the outdrive from getting out of the water while moving forward??

Re: Need help fixing Trim UP function and identifying switch use!

rpaldrich said:

Thanks for all the help.. In fact it was a couple of problems. First, the trim limit switch is bad but the previous owner had already jumpered the wires to let the trim switch still work, and it had no continuity in the down position. He just bypassed it.

Click to expand...

Very common. Most people can't be bothered with the time and expense of replacing (the kit is over $100, and there is a cuple of hours involved).

rpaldrich said:

After figuring that out, I had then decided it was a bad switch because of this:

The blue/white wire coming from the trim pump to the trim limit switch does transmit the power from both the up trim and trailer buttons...but the blue/white wire that continues on from the limit switch to the throttle handle is only for the trailer button. The Purple/white wire coming from the throttle handle to the trim limit switch is the one you need to test for 12v on when button is clicked up if your trailer button works, but up trim button doesn't. If you look at the diagram in the second post above, you can see that this allows the trailer switch to bypass the trim limit switch... the PURPLE wire is the switched wire connected to the trim switch, and I found a continuity problem in the wire. The PO had for some reason an extension spliced into the trim wires (maybe he wanted dual control of it at the transom) and the connection was bad. Anyway problem solved. All switches work.

Click to expand...

I have transom mounted trim switch on my boat. It's a proper Mercury part that comes with all the right plugs and connectors so there is no need for cutting and soldering. Sounds like the PO was a cheap bastard and trying to save a couple of dollars.. I really HATE that!!! because this is the strife it causes...

rpaldrich said:

Trim limit switch? I've heard replacement is a pain, and if its the only thing wrong... My gauge works, any problem with just using it to prevent the outdrive from getting out of the water while moving forward??

Click to expand...

The limit switch is there to prevent trimming up far enough to have the drive come out of the side supports. Once it is out of those supports there is very little lateral support, so if the drive is hit there is a real possibility of serious damage.

Chris........