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2018 Merc 90 EFI 4 stroke - Power Trim Up Does Not Work - Troubleshooting

MarkW775

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[h=2]2018 Merc 90 EFI 4 stroke - Power Trim Up Does Not Work - Troubleshooting[/h]
2018 Merc Serial 2B4937##

Power Trim "Up" Stopped working - Need some additional troubleshooting help or direction.

1. Down Works on Both Motor and Throttle switch.
2. I Reverse Blue and Green wires to lift motor and Down switch elevates motor, motor runs fine in either direction, power is good, hydraulics good. Not Motor.
3. Reversed existing relays, still same symptoms.
4.Replaced Both Relays, still same symptoms when Blue and green leads are reversed and normal. Swapped relay positions and still same symptoms. Assume relays are good at this point.​
5. Next Steps?

Does any one know where I can get an accurate wiring diagram?

Is there a fuse somewhere I am missing?

What would inhibit the Up only function? Is there interaction with a limit switch somewhere?

Does Calibrate do anything beyond a trim gauge calibration?

Any additional help greatly appreciated!​
 
I am going to assume that Merc wired the trim on the 4 strokers like earlier model 2 stroke 90's....a 2 wire motor drive...blue and green.

The control switches are in parallel. if you had a bad switch or wiring to the switch, unless you were between the engine mounted switch and the relays, with both switches inop, not a switch problem. The motor runs so it's not the problem.

The control relays are grounded at the relay mounting screw.....which could be corroded and not making good ground.... and get motor drive power from the red wire connected to the engines 12v distribution point through the 20 A fuse....which is good.

You have one control circuit per relay.....blue/white stripe with 12v for one and green/white stripe with 12v for the other. You have one power circuit per relay...12v in and ground for running the motor....12v red wire and black ground. I haven't cut a relay open but this senario makes sense: 3 contacts per relay. Common connection (output) for each relay goes to the motor via solid blue for up or green for down.

In the deenergized position, both relays ground their respective wire to the motor.....no trim drive, both wires to the motor grounded.


If the blue/white stripe wire sends 12v to it's relay, it will energize and switch it's contact from ground to 12v causing the motor to drive the engine up using the relaxed position ground connection from the green relay.

Operation of the green relay is the same.

The 20 amp engine fuse does control the 12v to the pair of relays suppling the drive power to the trim motor. Since one works, the fuse is good.

First thing I would do would be to clean up the relay mounting bracket mounting screws, especially the green relay mounting screw securing the ground wire (as this is where the UP relay gets its ground for running) and black ground wire terminal under each....remove the screws, clean, and reinstall. Check operation. If no change:

Pull the original UP relay and examine the contacts. See if one or more has corrosion/mold, any kind of crud. If you find one, investigate the under side of the relay socket for that pin in particular, and wiring to it for a broken/corroded wire. Your problem should be right there at the relays.
 
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As Texasmark said, the connections at the bottom of the up relay may be to blame. The power wires (the ones that actually work the motor) that carry a lot of current get hot and over time can relax their tight grip on the spade or pin connector. Find an appropriate connector for a test fit to see if one feels rather loose compared to the others and bend it back as needed. After that grab the old test light and probe to make sure that there is voltage available (or do that first depending on which tool comes to hand first). I am assuming that the relays are the square five prong types here also.
 
REPLY TEXT UNDERLINED:

I am going to assume that Merc wired the trim on the 4 strokers like earlier model 2 stroke 90's....a 2 wire motor drive...blue and green. Correct

The control switches are in parallel. Correct, (Blue/White/Green/White, red to common point) if you had a bad switch or wiring to the switch, unless you were between the engine mounted switch and the relays, with both switches inop, not a switch problem. The motor runs so it's not the problem. Correct

The control relays are grounded at the relay mounting screw..... No, Relay mounts were plastic to plastic, replacements are screwed into plastic , ground run to each relay) which could be corroded and not making good ground.... and get motor drive power from the red wire connected to the engines 12v distribution point through the 20 A fuse....which is good. 12V tested at each relay red lead, primary power is reaching both relays, zero corrosion anywhere (New Engines are nice to work on).

You have one control circuit per relay.....blue/white stripe with 12v for one and green/white stripe with 12v for the other. You have one power circuit per relay...12v in and ground for running the motor....12v red wire and black ground. I haven't cut a relay open but this scenario makes sense: 3 contacts per relay. Common connection (output) for each relay goes to the motor via solid blue for up or green for down. Correct, Tested the Green/white, 12 V when switch closed for down, Tested Blue/White 1.7 VDC when switch closed for down, this is our troublemaker. Applied 12 V to Blue/White and trim Up worked, relay engaged an motor raised.

In the deenergized position, both relays ground their respective wire to the motor.....no trim drive, both wires to the motor grounded. Correct, full ground continuity on all.

If the blue/white stripe wire sends 12v to it's relay, it will energize and switch it's contact from ground to 12v causing the motor to drive the engine up using the relaxed position ground connection from the green relay. Correct

Operation of the green relay is the same. The 20 amp engine fuse does control the 12v to the pair of relays supplying the drive power to the trim motor. Since one works, the fuse is good.Correct

First thing I would do would be to clean up the relay mounting bracket mounting screws, especially the green relay mounting screw securing the ground wire (as this is where the UP relay gets its ground for running) and black ground wire terminal under each....remove the screws, clean, and reinstall. Check operation. If no change: Not screws but did check for grounds on relays, full Continuity, All OK.

Pull the original UP relay and examine the contacts. See if one or more has corrosion/mold, any kind of crud. If you find one, investigate the under side of the relay socket for that pin in particular, and wiring to it for a broken/corroded wire. Your problem should be right there at the relays. Like new, no corrosion

Blue/White is the problem. I found controller pictured below with potted connections so no way to examine internals. Parallel switches feed into it and outbound go to relays. I cannot locate this part number online anywhere but it has to be the problem part, Blue/White only gets 1.7 VDC on output while input is at 12.7 VDC.

Can anyone source a replacement part or part number for this device?


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  • Control Box 2020-08-05 135429.png
    Control Box 2020-08-05 135429.png
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See Response to Texasmark: Blue/white only gets 1.7 VDC

Blue/White is the problem. I found controller pictured below with potted connections so no way to examine internals. Parallel switches feed into it and outbound go to relays. I cannot locate this part number online anywhere but it has to be the problem part, Blue/White only gets 1.7 VDC on output while input is at 12.7 VDC.

Can anyone source a replacement part or part number for this device?
Control Box 2020-08-05 135429.png
 
Pickup voltage on a 12v relay runs around 8-9 volts. 1.7 won't get it. If you don't have a crimp connector kit, HF and other places have terminal kits where you can just cut the bad connection off, strip the wires, and press on the new one...some kits have the crimping tool as part of the kit. Obviously size the terminal to the wire. Red/pink is probably what you'll need for the control wiring connections, but blue will work too, just crimp good and tight. Note the crimping tool is color coded on the crimper part of the tool. Some tools use the same size crimp for blue and red. Glad this is moving along.

If you are in fresh water and keep your rig indoors you don't need to water proof the connection. If you don't, HF and auto parts stores sell liquid rubber in a bottle...4 oz give or take with a brush in the lid....just complete the joints, plug everything in, test, and if ok just coat the whole thing with liquid rubber. Some RTVs are corrosive to copper circuit so I wouldn't recommend that for waterproofing.
 
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Pickup voltage on a 12v relay runs around 8-9 volts. 1.7 won't get it. If you don't have a crimp connector kit, HF and other places have terminal kits where you can just cut the bad connection off, strip the wires, and press on the new one...some kits have the crimping tool as part of the kit. Obviously size the terminal to the wire. Red/pink is probably what you'll need for the control wiring connections, but blue will work too, just crimp good and tight. Note the crimping tool is color coded on the crimper part of the tool. Some tools use the same size crimp for blue and red. Glad this is moving along.

If you are in fresh water and keep your rig indoors you don't need to water proof the connection. If you don't, HF and auto parts stores sell liquid rubber in a bottle...4 oz give or take with a brush in the lid....just complete the joints, plug everything in, test, and if ok just coat the whole thing with liquid rubber. Some RTVs are corrosive to copper circuit so I wouldn't recommend that for waterproofing.
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Thanks for info but it's not the crimp connection. Inside of Motor and contacts are dry and clean.
Dry clean 2020-08-05 174539.gif


The 1.8V is coming from the Trim Limit Kit Module, Blue White wire feeding the relay (see picture) - when the up trim button is depressed the unit supplies only 1.8VDC.
1-8 volt 2 2020-08-05 174539.gif

Merc Part Number #8M0118725
Trim Limit Kit Analog to Digital
Trim Limit A2D 2020-08-05 174539.gif

I think this is the bad part.
Not sure why it is necessary but it is part of the 2018 EFI 4 Stroke as an accessory.

Thanks for helping narrow down to the Blue/White Control Wire.
 
Fazt bullet may know where you can find a part...he may have one since he owns Grandpa's Marine Sales and Service, besides being a certified mechanic and many many posts on boating forums.

We could wire around it and go directly to the relays but in thinking about it, somewhere in the circuit you need something to stop the power to the trim motor when a mechanical limit of the mid section is encountered. Possibly there are 2 switches on the mid section, around the clamp brackets that deactivate the relay when opened due to arriving at a limit. That would be your orange and purple to name a couple of new colored wires. Purple (or red with purple stripe) is usually (ignition) switched 12v. Orange and yellow, or whatever the other odd color happens to be, would be the interrupt switch wiring.

Interruption would have to be to the coil voltage (blue/wh or green/wh) to the respective relay. That power lead would go out via an odd colored wire to the switch and come back another odd color and connect to the up or down relay....same with the opposite relay.

I'd trace the left side of the device and locate the termination point of those wires.

You can probably trace that out and might be able to wire around the device and still get the desired result...if FZ can't locate one.

My guess on the relay socket as pictured would be L-R terminals would be the low current energizing coil, center would be to the motor and top would either be 12v red or ground black with the bottom terminal the the other color.
 
I just looked in the manual for earlier 2 stroke engines and there are no extra components. Motor must be high impedance such that when in a limit it self limits the current. No wires but red, black, green-blue control with stripes and green-blue motor drive 2 relays with only those colors entering/leaving and the 20 Ampere fuse.
 
Put the part number listed on the part (8M0118586) in a www search engine. When the replies come up, there is one reply in particular that may be of interest to you. I can't post the www as the site cops will give me a ticket.

If you are using that system, it may help to understand the 1.7-8 v you picked up and it may not be a problem.

I got out my 2000 Optimax manual this morning looking for any help and the trouble shooting guide is just like what we have been doing....check for battery voltage at the blue/white input wire to the UP relay when the up trim button on the RC/engine is pushed. Reconnecting that and disconnecting the blue wire to the motor and checking for 12v there when the button is pushed. With the button in the off position, disconnect blue and green wires to the motor and check for ground on both.
 
There is one possibility we may have overlooked, is there a tilt sensor that is telling the A/D controller that the engine is already high enough? With several extra wires more than needed to just convert analog to digital one or more may go to a sensor that might be disconnected for a test.
 
Could be. There is a tilt sensor mounted to the engine on the Port side, visible just above the transom bracket with the engine fully tilted up. That is primarily to drive a dash tilt meter.....but to be a tilt limiter, and some degree of accuracy one would expect...................Bingo!!!!!!!

Just dawned on me.

The Trim/Tilt cylinder has a bypass valve that relieves the hyd pressure when tilted above the trim limit angle and RPMs exceed something like 2000 (serv manual #). if the engine were tilted above the PT limit, the pressure the thrust of the prop was putting on the ram would unseat the bypass valve and the ram would sink back to the max trim position. Well the pump pumps the trim setting....the overload unloads if trim is exceeded..... the same pump pumps on up operating in the tilt function........if you are at max tilt, the pump will still be running and will drive the hyd pressure to the point that the same overload valve will unseat and allow the pump to continue to run (with the UP switch energized) till the operator takes their finger off the switch....with no damage to the motor. Piece of cake, nice, simple, and reliable.
 
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But would that prevent the pump from working in the first place? It would seem that either the a/d controller is bad like MarkW775 thinks or something is telling it not to work.
 
But would that prevent the pump from working in the first place? It would seem that either the a/d controller is bad like MarkW775 thinks or something is telling it not to work.

I was trying to decipher that little adapter in his picture and all the wires.....in short could there be TT position sensing switches on his engine that weren't on older models that had 2 switches, 2 relays, and 2 wires to the motor.

I think I have exhausted my resources here. I think that adapter is for the (apparently digital) 4 readout multifunction (accessory) that puts 4 functions on one display. I can't find any information on that other than purchase information. I would surely think that any wires going to that module were strictly for metering and would be "shunted/Y'd/T'd" off the lines that actually do the work.
 
I guess it's time for a factory service manual or throw parts at it.

Service Manual on Backorder right now... :)

Here is the part: Unfortunatley $100 plus shipping.
Trim Limit A2D 2020-08-05 174539.gif

Sorry for the delay in responding.

There is this sensor that looks like it provides tilt position. with purple/Black/Blackwhite wires. I tried to disconnect (no effect) tried to ground the blacks on controller side, no effect, I did not locate that part in any catalog yet. Cannot find any information on it.

rTilt Sensor 2020-08-07 180716.gif

Here are the wires: red circle to tilt sensor - Purple wires to A2D Converter
Tilt Sensor wires 2020-08-07 180716.gif


Thanks for the continued help
 
It does act like something is preventing the Up Signal on the Blue/White since reversing motor leads works every time to raise/lower the unit with the down button. This module must be doing some valued function or it would not be there. I do not have any trim indicator at the helm, (But maybe it was factory wired for a multi-function display?) nothing heading that way except the 3-wires to the throttle trim button. But it seems to make sense that it must have some tie in to "up" function since "down" works and maybe it does interact with the tilt sensor to protect the motor while operating?

Would be nice if there was some information on it.
 
Texasmark, check me on this. The only reason I can think of to need a digital conversion of an analog signal is to allow the device in question here to limit the tilt of the engine and likely without reporting to another module. If that is the case then the only data inputs will be from the tilt sensors which should be able to be checked for varying resistance or voltage feedback depending how they did it. I would think that if the sensors have two wires going to them they would be power in and a return signal, if there are three wires it would be power, ground and a return signal. The return signal to the tilt a/d unit should be testable and if the results look reasonable (voltage one way for up and another way on down) and if there are two sensors they will either be one for up and one for down or both work in tandem and the results should look the same. We have the benefit of having one side of the system working which might help us to understand how they went about doing this.
 
As swagon , said , you could possibly have short on , boat side.
✔ voltage at boat side harness plug. Then check grounds, an plug in connection
 
I had the colors wrong (needed my glasses) I found that the trim angle sensor is analog thanks to the Texasmark tip " (8M0118586) in a www search engine." The wire colors are purple - (measures 12V) Black/white and then a brown. I suspect the brown is the "Signal"" wire. +/- Signal makes sense. I can't play with it now due to rain but I will follow up. Looks like Part number for the Trim Sender is 8M0094923.

What do you suspect i should see on the brown? a change in voltage with trim angle?
 
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I had the colors wrong (needed my glasses) I found that the trim angle sensor is analog thanks to the Texasmark tip " (8M0118586) in a www search engine." The wire colors are purple - (measures 12V) Black/white and then a brown. I suspect the brown is the "Signal"" wire. +/- Signal makes sense. I can't play with it now due to rain but I will follow up. Looks like Part number for the Trim Sender is 8M0094923.

What do you suspect i should see on the brown? a change in voltage with trim angle?

Found this on another search: "4 stroke tilt limit calibration
Ok, I've just had a travelling Merc mechanic fit the optional tilt limit module ...

From what I can remember; with key on, trim to your max point with the orange wires of the trim limit module connected, disconnect wires and cycle key off. The trim switch on the cowling will override the trim limiter. Trim limit only works with the control box trim switch.

Gauges/MercMonitor have nothing to do with actually limiting trim travel. That is done with the trim limit module.

Its been several months since I’ve programmed one, so my instructions may not be 100% accurate."


Could this be a programming issue that got screwed up?
 
Texasmark, check me on this. The only reason I can think of to need a digital conversion of an analog signal is to allow the device in question here to limit the tilt of the engine and likely without reporting to another module. If that is the case then the only data inputs will be from the tilt sensors which should be able to be checked for varying resistance or voltage feedback depending how they did it. I would think that if the sensors have two wires going to them they would be power in and a return signal, if there are three wires it would be power, ground and a return signal. The return signal to the tilt a/d unit should be testable and if the results look reasonable (voltage one way for up and another way on down) and if there are two sensors they will either be one for up and one for down or both work in tandem and the results should look the same. We have the benefit of having one side of the system working which might help us to understand how they went about doing this.

Back in the days of Lake X testing in Florida, Mercury did exhaustive testing including running boats over logs and sandbars. That caused them to add shocks so that when the LU hit something and knocked the LU up in the air, the engine wouldn't come slamming down and possibly knock out a transom.

Then they realized that at WOT, hitting something pushed the prop out of the water and over revving was a serious concern so they mounted a Mercury switch on the mid-section such that the ignition was killed (know not just what was interrupted) until the LU got back in the water and prevented overreving.

Then they decided you need a dash mounted trim position sensor (all of this not necessarily in actual time line sequence) on outboards like they had on I/Os since in a lot of/most I/Os you can't see the outdrive position from the helm...I "think" I recall Chris 1956 identified that sensor as a variable resistance in series with the dash monitor across 12v with the position of the LU varying current through the meter for position readout.

Then they added power trim making the existing shock absorbers hydraulic cylinders, movable with a hyd pump and up-down switch which was later moved to the single lever Commander 2000 and 3000 control handle for convenience. Later yet, they moved the PTT system to the space between the clamp brackets.

I have no idea as to intent of his current auxiliary system and it's purpose we have been discussing. All I can relate to is the fact that the service manual for the 2000 115 and related hp Optimax engines, shows a wiring harness for a dash mounted 4 item gauge.

That's the same manual that shows a trim setup exactly the same as is on my carbureted 115 2002 2 stroke and other hp engines of the 3 and 4 cylinder series since 1996 and later (series for which the current manuals were published and updated in 2015. I would think that if the module had anything to do with the trim operation itself, there would be widely published data as to what and why and some wiring diagrams. I am at a loss!
 
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For the moment then markw775, I would suggest seeing what measurements can be had from the tilt sensors. There is no telling what you should expect other than look for a change as the engine goes up and down. It seems likely that the a/d unit is bad but it's always nice to have tried to rule out other things before buying an expensive part and THEN checking the other parts. Btw, for a temporary repair you can always bypass the converter.
 
For the moment then markw775, I would suggest seeing what measurements can be had from the tilt sensors. There is no telling what you should expect other than look for a change as the engine goes up and down. It seems likely that the a/d unit is bad but it's always nice to have tried to rule out other things before buying an expensive part and THEN checking the other parts. Btw, for a temporary repair you can always bypass the converter.

Thanks for the great Info and help everyone. Sorry for the delay in response. The problem was definitely the Trim Limit KT-A2D Part No 8M0118725. Took a long time to come in with COVID. I decided to get a new trim sensor as well , turns out that it was not that part but I didn't want to delay it anymore. Now I have a spare, as they say time is Money...

I did make a quick manual wrap around reverse switch in the mean time since the down function worked, it just flips the DC wires polarity with switch operation. So Down switch works down trim and then works up trim after reversing polarity. Functional but not clean. I left the rest in place from the A/D Converter since it connects with the engine ECM.
 
Thanks for the great Info and help everyone. Sorry for the delay in response. The problem was definitely the Trim Limit KT-A2D Part No 8M0118725. Took a long time to come in with COVID. I decided to get a new trim sensor as well , turns out that it was not that part but I didn't want to delay it anymore. Now I have a spare, as they say time is Money...

I did make a quick manual wrap around reverse switch in the mean time since the down function worked, it just flips the DC wires polarity with switch operation. So Down switch works down trim and then works up trim after reversing polarity. Functional but not clean. I left the rest in place from the A/D Converter since it connects with the engine ECM.
Thanks for that information I'm having the same problem. Everything you try, I did the same. Will look in ordering the part .thanks.
 
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