Outboard wiring harness

[Ski213]

98 Stratos boat,  97 Johnson 225 outboard late 90s models. 

Does anyone off the top of their head know what is grounded off the ground wire coming from the outboard headed to the console/ignition switch?  I have some wiring diagrams but they’re kind of vague regarding that. 
 

The ground wire had melted insulation behind the console throughout as well as at the plug on the side of the outboard.  Just trying to figure out what is going where right now. Anything that will help me shorten the troubleshooting process is appreciated. Im thinking it handles instruments and instrument lighting only given how small it is.
 

Also, do you guys think I should be looking more for a short somewhere or a weak connection. What connections I’ve accessed so far look and test good but I’ve actually never dealt with a situation where the wire is damaged along an extended length. 
 

Thanks. 

[Way2slow]

The ground/battery negative is the black wire going to the switch.  The kill wire going back to the ignition should be black/yellow.  Other than a couple of gauges, the ground wire should not be connected to very much.  It's main purpose going up to the switch is just to provide a ground at the switch for the kill circuit. 

Yes, there had to be short to smoke that ground wire.  In a short, the smaller wire is going to be the one fry, so look for a larger red/battery positive wire that has gotten into it.

Now you just have to hope it only took out the wire. 

To trouble shoot, start by connecting you volt meter to battery negative and the positive meter lead to the bare ground wire a make sure there is not voltage on it.  It could still be shorted and just burned itself into where it connects to the engine/battery negative.

If you are having major problems trying to follow the wires, they make I circuit tracer that will tell you if a wire is open or shorted and place a signal on the wire that you can use a toner to follow it.  The one I have and bought many years ago was about $300 then, but it was a new gadget to the trouble shooting world back then.  I would think by now they would be a lot cheaper.

Don't know what you might be getting for your money but here's something similar at Harbor Freight, the good one I saw are still a little pricey.  https://www.harborfreight.com/cable-tracker-94181.html?cid=paid_google|||94181&utm_source=google&utm_medium=cpc&utm_campaign=&utm_content=&gclid=EAIaIQobChMI6arW0eq67QIVCkqGCh07yAVAEAQYAyABEgKZ2PD_BwE

[Ski213]

Thank you!  I “accidentally” found the melted insulation when I pulled part of the cluster to blow water out of the water pressure gauge line. I had just run the outboard on the hose and didn’t notice any issues but I wasn’t looking for them I suppose. I disconnected the ground leads from the batt at that time.

 

I’m not showing any continuity from the ground wire that is damaged to +bat (all grounds disconnected at battery) but  I didn’t check from the damaged wire to battery ground for voltage. The majority of damage seems to be on the ground wires at some of the gauges. Worst of it at the tach ground stud. Even melted some of the back of the gauge. I’ll try to attach a pic. I think I might be able to borrow one of those circuit tracers. 
 

I appreciate your help. 
 

 

[Way2slow]

Did it melt it back to the key switch and on back into the motor.  What I'm seeing there means there had to be a problem under the dash or in the boat wiring.  Maybe where someone was using that ground for something they wired.  One of those wires on the tach should go to the key switch, the other would go to one of the other gauges, maybe the battery voltage or trim gauge.  There are only a couple OMC provided for.   It's going to start at the source of the short and go back to the battery or engine block, where ever they pull their ground from.  So, if you keep following those wires on the tach, one should go to the switch, that one is not the problem, the other one will lead you to where the short started if you just keep on following it.  When you quit finding melted insulation and it turns to good black insulation, that's the source of the short.

[Ski213]

I haven’t pulled the switch yet. Just pulled the clusters out of the console and checked under the engine cover once I realized the melted wire had continuity to the neg battery cable to the outboard. It is melted at the plug on the engine though to an extent so I’d imagine it is at the switch as well.
 

I think I’m getting what you’re saying. The furthest point of damage away from the ground source is gonna be, or be right at the issue right?  Makes sense. I’m hoping end of the line is in the console but I’m thinking that ground may daisy chain through the dash then head to the bow panel. I’ll have to keep tracing. 
 

Thanks for the direction. 
 

Thanks again. 

[Way2slow]

Yes, the melt is going to start at the source of the short.  Now, that's not saying the melt hasn't created other shorts if it melted other wires next to it.  If only the black wire is melted, and it did not melt other wires to it, you should be ok, the only problem is, in a tight multi wire cable like the control cable about the only way to tell that is to ohm each one out.

The only way it could not lead to the short is if someone grounded both ends of the black wire, which is not common.

If it went all the way back to the motor, then it went though the control head where it connects onto the back of the switch. 

You also have to figure, this could have happened a long time ago and not recently.  As long as it just over heated and melted the insulation, and not the wire itself, the short could have burned away and cleared itself and still be working fine.  I would still want to find the source of the short though, would not be fun to be one the lake and see smoke start coming out of the boat.

You also have to remember, the positive wire that caused the black wire to melt has to be larger than the black wire.  If it is the same size, they both melt, if it is smaller it usually melts into.  If it's larger, the black wire melts and it only gets warm.

[WRB]

The basics are shorts happen when power and ground conductors contact. This usually happens at the power and ground connection without insulation. Loose terminals or bare wire or both. Power wire is fused to prevent fire, ground wire are not fused. 

As suggested start trouble shooting the power source. You should have a blown fuse or tripped circuit breaker that indicated what power wire was shorted.

Tom

 

[Ski213]

I’m somewhat concerned about that multi wire cable. Even if it all ohms out ok I’m assuming the inside of it looks like everything I can see. As you mentioned, the boat smoking would not be a great situation. I think I found the cable for sale.

Wasn’t free but not terribly expensive. I’m sure it’s a treat to replace though. 
 

I’ve not done anymore tracing tonight due to weather but hope to get back on it later in the week. I haven’t found any blown fuses or tripped breakers yet but I haven’t checked them all. 
 

Thanks guys.

[Way2slow]

Find the source of that short before you put that new cable in.  We don't won't go for that, third times a charm.

 

The short is in the boat not the wiring harness so it could do it again.

 

Most likely, the cable is going to be tie wrapped to the side of the boat with the other cables so getting it out might be hard

[Ski213]

Ha! No definitely don’t want to go that route.  Gonna chase down the source first for sure and address that.  Not looking to burn it down and don’t want to pull that cable more than once, heck I don’t really want to even pull it once.  I go back and forth on even replacing it if it ohms out ok after I clean up the rest of the mess but I think I’d sleep better if I did. 

[Ski213]

As a quick update I did end up checking voltage from bat- to the one of the melted ground wires. Reads 12v but won’t light up a test light. Pulled the ignition switch and all the wiring to it looks intact. No tripped breakers and no blown fuses anywhere on the boat. Having a little trouble figuring out what’s coming from where. A couple ground wires head down to a giant bundle of wires behind the panel by the hotfoot. This weekends project is gonna be to cut the cable ties off that and start pulling it apart between rain showers. 

[Guitarfish]

Check and believe continuity only and you won't go wrong.  Potential 12v is what you are reading.

 

Let me give you an example:  One fixture doesn't work in your landscape lighting.  You go to the wiring at that fixture and it reads 12volts on your meter, but doesn't light.  You find out after some digging that the gardener nicked the wire when he was planting a rose bush the other day for your wife.  The current is now going to ground (literally in this example) and doesn't have enough left to power a bulb. But your meter still reads the potential 12volts.  Hope that makes sense.

 

The dead short (to ground, black wire) is absorbing the current and caused the heat.  Separate and test each run/wire.  Tedious but needed.  Don't reuse any marginal wiring.  Be safe.

[Way2slow]

If you reading 12v on a ground, That means it's no longer connected to ground/battery negative so it has probably melted the copper conductor at the motor or somewhere along the path.  Take a continuity reading between the back of the tach and battery negative.  Reading a voltage without a load can lie to you.  You can have a blown fuse that reads voltage but as soon as you turn on what it controls and place a load on it, the voltage goes away. If it's not lighting a test lite, monitor the voltage with meter, connect light and see if voltage goes away. 

Can't get into much detail, I guess I broke a knuckle today and it's swollen, and supper painful to try on type on this keyboard.

You are going to have to find where that short is/was, or you are asking for trouble.

[Ski213]

Sorry for not replying back quicker. @Guitarfish yes that does make sense. Thank you.  Hope you hand is feeling better @Way2slow  

 

Have only had time to mess with it here and there for a few minutes. There is continuity back to the battery ground from the tach ground. I did determine that the ground loops back to the battery so that wire at the tach or I guess really that whole wire, can get to ground two ways. I’m calling the control cable ground part of the OB harness (gauges, ignition switch) and the other harness the boat harness (pumps, nav lights, gauge lights, etc.). They’re tied together behind the cluster. I can’t swear it’s factory but it appears to be. The majority of those ground wires at the console are I believe 16ga. As it heads toward the battery on the boat harness it steps up to a 10 ga I think. That’s where the damage stops in the boat harness. The one in the OB harness stays 16ga all the way back and is damaged almost to the point where it lands on the starter with the battery cable. I can’t find any damage anywhere but on what I’m gonna call the main ground wires. None of the grounds to pumps, etc have any visible damage. Everything works. I put an amp clamp on the damaged ground at the tach to see if I got any kind of crazy current while turning everything on. I didn’t really get anything at all odd. Did get a blip when I bumped the starter but only around 0.2A. Also something that I noticed was if I reversed the leads on the meter while reading continuity from tach ground to batt ground and switched the key to on, I lost continuity. Perhaps that’s normal. I’m assuming that there’s a diode or something that I’m reading through in the ignition?  Maybe. That is with the boat harness ground disconnected so the outboard harness isolated. 
 

Any possibility that if I had a crap connection on the ground cable (which I didn’t find yet) from the batt to the outboard and had cranked the motor or trimmed the engine up it could’ve gone looking for ground through the ob harness, into the boat harness and back to batt -?  
 

Thanks guys. 
 

 

[BKeith]

You may have been reading on the wrong side of the key switch.  That or you are only getting the ground through the power pack.  One side of the key switch has a constant that goes back to the block, which is grounded to the battery.  The other side Is a switched ground that's applies the ground to the power pack when the key is off, and the ground is removed when the key is on.  This should be the black/yellow wire on the switch, and the ground should be solid black if I remember right. 

The switch being on or off should have no affect on the ground wire on the back of the tach, unless somehow, or someone has that ground wire going to the switch and the wrong side of the switch.  The ground wire for the instruments and lights on the console should be on the boat ground..  

If you are reading through a diode, that's easy enough to check by just putting the meter in the diode function and reversing the leads to the meter. On way you will be reading about .500 - .700, the other way you should have 0.  

You can do the same thing with meter in ohms, just by reversing the leads but the it's more reliable to use diode, since in the diode function, you are actually reading a voltage drop across the diode and not a resistance.  

[Ski213]

Ok I’ll check that out.    On mine there are three plugs at the ob that make up the cable that runs to controls and key switch. Two of them are 6 pin. One of those appears to be solely for the ignition switch. It’s appears and ohms out ok. It has the black yellow as you said and on mine black white for constant ground to the switch. There’s another 6 pin that has the damaged ground in it. That 6 wires appears to be mostly VRO/engine temp related so I guess that’s heading to the system check gauge  or whatever deal at the console. I assumed the black in that plug given the damage was the same wire as at the tach.  I’m gonna have to separate some stuff to verify that now that I’m thinking about it though. The last plug is just a 3 pin that is trim sending unit to gauge and trim up/down from the remote trim controls.

 

I’ll have to separate the grounds off the starter and do some more digging. I’ll try to do a better job isolating stuff next time I get to work on it. It’s making it harder for me getting 5 min here and 10 there. Hopefully this weekend I can just get on it and stay on it for a few hours. I really appreciate the assistance!  

[Way2slow]

It's been several years since I've messed with these but if there are two control cables one is going to the remote key switch.  The other is probably all the sensors for oil injection, temp etc and goes to the alarm buzzer mounted somewhere near the control box,  but the ground in that cable should not be used as the ground for the boats wiring, if it is, I would see about removing that connection and running me a 12 ga wire for the boat wiring.  The wire is not large enough to handle much current.  You have to remember, if you are pulling 10 amps on the positive wire, the ground wire has almost that same load.  Some is lost through the load so it's claimed the ground can be one size smaller, but I keep them the same.

Your motor does not have the systems check, that's built into the tach,

When I wire a boat, I I use two six lug terminal strips mounted somewhere in the battery compartment.  One for the positive and one for the negative.  I run a 10 or 12ga wire  from the battery to those and then all other electricals are run to those.  That way, you only have the motors battery cables and that one wire and the onboard charger connected to the battery.  I've seen some have a half dozen or more wires connected to the batteries.  

[Ski213]

@Way2slow mine is one of those with quite a few connections at the battery. I’ve been threatening to change that for awhile. Guess now is a good opportunity. Gonna try to get after separating everything out tomorrow. 
 

Something I’ve always wondered that you may know the answer to. Why did OMC run a separate green ground wire to the battery that only serves the fuel sending unit?  I don’t know if your Jav is that way but I know of several Stratos that are done that way. 

[Way2slow]

I guess you are asking why OMC because they owned Stratos at that time. 

I would have to guess, that was the easiest, cheapest way to ground it.  Like you said, until you get to the front of the boat, just about everything is powered by a separate wire to the battery for most of the stuff in the back.

Two of these make things much nicer .  This one does not show the jumper straps so be sure to get the ones that do.  That way you can make one side all commons and then connect the individual connects to the other side. 

https://www.lowes.com/pd/Utilitech-Quick-Wire-Connectors/999953938?cm_mmc=shp-_-c-_-prd-_-elc-_-google-_-lia-_-106-_-electricalaccessories-_-999953938-_-0&placeholder=null&ds_rl=1286981&ds_a_cid=112741100&gclid=EAIaIQobChMI8N6btuuN7gIVgaGGCh3-7Q0UEAQYAyABEgLLb_D_BwE&gclsrc=aw.ds

 

Something like this  or single ones 

https://www.alliedelec.com/product/marathon-special-products/600rjs05/70254811/?utm_source=google&utm_medium=cpc&adpos=&scid=scplp70254811&sc_intid=70254811&gclid=EAIaIQobChMI4dGB6O2N7gIV3QeICR38JQpQEAQYCCABEgKMHPD_BwE&gclsrc=aw.ds

 

Here's everything on ebay

https://www.ebay.com/itm/Terminal-Block-Boat-Wire-8-Positions-Dual-Row-600V-15A-Electric-Barrier-Strip/333850764947?hash=item4dbb0e6693:g:--MAAOSwNTBf-CiS

[Ski213]

Well over the last three months I haven’t had a ton of free time but a little at a time I’ve dug through every accessible bit of the wiring harnesses. I’ve never found the source. All what I’m calling the branch circuit grounds (lights, pumps, etc) are intact and the meter says they’re good. I did pull the control cable out with the intent of replacing it. Everything checked ok with the meter. Visually checked the ground conductor where the insulation had melted then rigged up a sort of load tester and after it all seemed good I put it back in the boat. I replaced all the damaged wire in the console and harnesses. Had to re pin several molex connectors as well.
 

I’ve run all the items on the boat while monitoring the ground wire. It all seems ok except for one deal. I had bumped the starter before and saw a blip on the amp clamp on the ob harness ground in the cluster. I put it on the hose and actually cranked it. I got 3A draw in the cluster for about the first few cranks then it falls off as it continues cranking and starts. 0A when running. (This is with the ob harness and boat harness grounds linked as they originally were. If I unlink them no current.  The battery cable to the starter and that ob harness ground land on the same stud on the starter. I guess it’s running up that ob harness to catch ground on the boat harness. I’ve unlinked them. I did the math and the boat harness ground is more than sufficient size for what’s on it. I can’t find anything wrong with the connections at the starter or in the battery cable so I’m not sure why it was looking for ground in two paths. Thinking about replacing the battery cable anyway though. Am I wrong to be concerned that I got that 3A draw where I shouldn’t have?  It’s no problem for that wire to carry that 3A but it just doesn’t seem it should have been there at all. I can prevent it by having the two harnesses isolated from each other but it still seems like it shouldn’t have happened either way. Thanks for all the help. I appreciate it. 

[Way2slow]

A ground wire is going to show the same current as positive wire of the circuit.  If you have 50 watt bulb wired four feet from the battery drawing 4 amps on the positive wire, it's also going to be drawing approximately four amps on the negative wire.    If it's a good connection, you won't be reading any voltage but it still has the current.

That was probably something with the ECU and starter solenoid.  The motor doesn't need a battery/current source to run.  Just to get it started.  It also has a cold start idle up circuit for about 10 seconds that might have been drawing a little.  There is a coil on the stator for the idle up but I've never really read up on how it reacts with the ECU.  It's just on of those things I know it's there and know what it does, but never dug into the details of how it does it.

[Ski213]

18 minutes ago, Way2slow said:

A ground wire is going to show the same current as positive wire of the circuit.  If you have 50 watt bulb wired four feet from the battery drawing 4 amps on the positive wire, it's also going to be drawing approximately four amps on the negative wire.    If it's a good connection, you won't be reading any voltage but it still has the current.

I see what you’re saying there. I guess my concern was where I’m reading the current away from the battery cable when the starter engages (and there’s no other draw or very little). I still read 20 something amps on the battery cable but I also get that 3 up at the cluster. I’m terrible at explaining stuff so

i did this crappy sketch to maybe better illustrate it. Sorry to be taking so much of your time on this but I always appreciate the education. 
 

32 minutes ago, Way2slow said:

A ground wire is going to show the same current as positive wire of the circuit.  If you have 50 watt bulb wired four feet from the battery drawing 4 amps on the positive wire, it's also going to be drawing approximately four amps on the negative wire.    If it's a good connection, you won't be reading any voltage but it still has the current.

That was probably something with the ECU and starter solenoid.  The motor doesn't need a battery/current source to run.  Just to get it started.  It also has a cold start idle up circuit for about 10 seconds that might have been drawing a little.  There is a coil on the stator for the idle up but I've never really read up on how it reacts with the ECU.  It's just on of those things I know it's there and know what it does, but never dug into the details of how it does it.

Sorry for some reason I just could see the first paragraph of your reply when I replied. Thanks!

[Way2slow]

I will have to see if I can find a manual and see how the thing is wired.  Sounds like the negative side of the solenoid might run on that wire.  They may be running that negative to the neutral safety switch.

 

I decided to put my walking man avatar I used on Scream and Fly for years on here.  Seems strange to see him to see him there I've gone so long with out anything there.