Forward power trim switch

[knoell3]

My aft power trim switch on the throttle works fine but the toggle switch on the foward deck does not. Replaced toggle switch with no sucess. This is a 1985 Lowe bass boat with a Mariner 90HP motor. Question is: is there an inline fuse that might be causing this?

Thanks.

 

[Texasmark]

Re: Forward power trim switch

I don't think so. I have throttle handle, engine mounted, and bow mounted switches. All are wired in parallel so that any one you activate will produce the same results. The current available in this circuit is very light so the opportunity to melt the wiring insulation in case of a short is minimal, hence no requirement for a fuse.

I am trying to understand where they would tap into engine wiring to add the bow mount switch but I haven't yet. I may go out to my boat later and see if I can find it on my boat. Near the remote control box is probably where they do it, but would have to cut into the outer layer of encapsulation of the wiring harness.

Will check it out and get back.

Mark

 

[Texasmark]

Re: Forward power trim switch

I don't think so. I have throttle handle, engine mounted, and bow mounted switches. All are wired in parallel so that any one you activate will produce the same results. The current available in this circuit is very light so the opportunity to melt the wiring insulation in case of a short is minimal, hence no requirement for a fuse.

I am trying to understand where they would tap into engine wiring to add the bow mount switch but I haven't yet. I may go out to my boat later and see if I can find it on my boat. Near the remote control box is probably where they do it, but would have to cut into the outer layer of encapsulation of the wiring harness.

Will check it out and get back.

Mark

Power to the bow section of my boat is via a red wire routed from under the dash with an inline fuse. The low side trim switch wiring is a blue and a black/yel which go back to the under side (back) of the remote control where they are incorporated into engine wiring.

So there's my answer and could be the fuse you are looking for if you don't have a separate fuse panel where you might find a similar "power distribution" fuse.

Mark

 

[knoell3]

Re: Forward power trim switch

Power to the bow section of my boat is via a red wire routed from under the dash with an inline fuse. The low side trim switch wiring is a blue and a black/yel which go back to the under side (back) of the remote control where they are incorporated into engine wiring.

So there's my answer and could be the fuse you are looking for if you don't have a separate fuse panel where you might find a similar "power distribution" fuse.

Mark

Hi Mark and thanks for your reply and checking this out on your boat. Looks like my wiring is 3 wires, green, blue and purple and either travels through the throttle box or is wired into it before proceeding to motor. I have 3 wires that are green, purple and blue...same color as those coming from the throttle box. Suspect if there is a fuse that it is in line since it does not go through my fuse panel. I can take out front glove box and see in upper bow. Maybe I can find a fuse there. Thanks again for looking and responding.

Chris

 

[Texasmark]

Re: Forward power trim switch

Hi Mark and thanks for your reply and checking this out on your boat. Looks like my wiring is 3 wires, green, blue and purple and either travels through the throttle box or is wired into it before proceeding to motor. I have 3 wires that are green, purple and blue...same color as those coming from the throttle box. Suspect if there is a fuse that it is in line since it does not go through my fuse panel. I can take out front glove box and see in upper bow. Maybe I can find a fuse there. Thanks again for looking and responding.

Chris

Normally inline fuses are placed where they are readily accessible. Under the dash is a prime spot for OEM boatbuilders who don't incorporate a fuse panel in a convenient location.

I just had a look at the wiring diagram for the Merc Commander 2000 side mount control. I have a 3000 in my boat, but it is not covered in the service manual for my engine; just the 2000. The difference in the two is that the 2000 mounts on the (inboard vertical) side of the gunwale and the 3000 mounts in it, requiring you to depress a large black button to initiate fast idle, unlike the 2000 which has a lift lever at the rear.

Power to the remote wiring harness is a red wire coming off the starter solenoid (on the starboard side of the block near the starter) small red wire. As soon as it leaves that terminal (junction) it incorporates a 20 amp fuse....on my engine the fuse is within 6" of the starter solenoid. The output of the fuse is power to the remote cable plug which connects to everything forward. So, unless you have an aftermarket somewhere else on your boat, there is your fuse. However, if it were to blow it would (should) knock out all Merc engine gauges and anything forward requiring 12v to operate that is associated with the engine, including cranking and choke function.

Power inputs changes from red to purple (colored wires) at the ignition switch and purple is used in some places for power along with red. I do now know the distinction between the two colors...possibly purple is only hot when the ig sw is on or in acc position.

The blue and green wiring is between the engine connector and the switch on the throttle/shift lever. I found no external connection for forward mounting a trim switch, however, I did find a "tach/accessory" plug with a pin that is used for boats with a trim position indicator....like an I/O would have as one of the possible accessories.

Therefore, it is my opinion that your OEM boat mfgr broke into the wiring between the remote control connector and the actual remote box where he picked up the purple, green, and blue wires and probably there is no additional fuse.

The 12v supply in the wiring in my boat is not engine associated and therefore was fused separately. It runs nav lights, a forward night light, a depth finder, and the forward TT switch.

Best I can do.

Mark

 

[knoell3]

Re: Forward power trim switch

Hi Mark, and thanks for your response. I trace the 3 wires last night and believe the middle wire (purple) is the hot wire back to the positive side of the battery. The green and blue (top and bottom post of switch) go into the motor, presumably to the trim motor. I put a meter on the purple wire and expected to see 12 volts and saw .03 volts. I believe I have a short in that wire and my plan now is to run a 12 volt lead from the battery to that post on the switch and see if it works. I think it will. Thanks again for looking into this and your posts.

Chris

 

[j_martin]

Re: Forward power trim switch

Hi Mark, and thanks for your response. I trace the 3 wires last night and believe the middle wire (purple) is the hot wire back to the positive side of the battery. The green and blue (top and bottom post of switch) go into the motor, presumably to the trim motor. I put a meter on the purple wire and expected to see 12 volts and saw .03 volts. I believe I have a short in that wire and my plan now is to run a 12 volt lead from the battery to that post on the switch and see if it works. I think it will. Thanks again for looking into this and your posts.

Chris

Sometimes a crimped connector will oxidize and open up, even though it looks good. It will usually feel slightly loose.

It would be criminal to run a small gauge wire to the bow of the boat without a fuse in it. (fire waiting for opportunity to happen.) Most bass boats of that era have a distribution fuse panel, often under the driver's console. The broad clamps on tube type (3ag) fuses tend to heat up under load when they age and blow the fuses. Usually the aft trim switch will steal power from the harness, and the front one will be separately fused.

The other thing that happens on bass boats of that era is there are sometimes multiple taps cut into the main control harness, not done properly (scotchlock IDC, for instance) that fail in time.

Any boat I've bought usually has to be completely re-wired to make it safe, reliable, and serviceable. My wiring is routed from screw type terminal strips, with breakers or sealed tab type fuses, soldered water proof insulted terminals, and an overall laquer seal against the elements. Logical layout and a few pages of documentation make it very easy to troubleshoot.

hope it helps
John

 

[knoell3]

Re: Forward power trim switch

I have this working now. The forward PTT switch was the last thing to get working. The purple wire on the center 3 postion switch is in fact power with the blue and green going to the PTT motor solenoids. I guess there was a break/short somehwere in it so I tested using a spare garage battery grounding off the boat to complete the circuit and it worked, so I just ran a new wire to the cranking battery, put a 25 amp fuse in line, and it works fine. I replaced every switch and electrical connector on this boat and replaced the fuse corroded fuse panel with in line fuses. Recommend anyone getting a used boat with "things" not working do the same. Once I did this, everything electrical (except forward PTT switch at the time) started working. Also re-did all splices by soldering and using heat shrink. Thanks for replies and advice. This is a great forum for information.