Wiring Harness
Printed From: CorrectCraftFan.com
Category: Repairs and Maintenance
Forum Name: Engine Repair
Forum Discription: Engine problems and solutions
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=42597
Printed Date: April-28-2024 at 8:27am
Topic: Wiring Harness
Posted By: Gravel_Laker
Subject: Wiring Harness
Date Posted: April-11-2018 at 12:06am
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Looking to replace this wiring harness or a 1971 Mustang with a Chevy 305 5.0 in it. Anyone have an idea where to get one or even where I can find the wiring schematic?  
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Replies:
Posted By: Gary S
Date Posted: April-11-2018 at 12:35am
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I'm not sure this is even it but check out https://bpi.ebasicpower.com/shop/mercruiser-sterndrives/electrical-system/wiring-harnesses/wire-harness-for-omc-volvo-crusader-pcm-no-bracket-6-feet-round-9-pin" rel="nofollow - ebasic power they have several different ones ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1711&sort=&pagenum=1&yrstart=1966&yrend=1970" rel="nofollow - 69 Mustang HM SS 95 Nautique Super Sport |
Posted By: shierh
Date Posted: April-11-2018 at 12:00pm
| You could make your own and use terminal strips instead of pin connectors. Nothing wrong with using same color wire with wire labels on them as long as you keep a chart in your boat book. The harness is basically to make it quicker to install and remove the engine. Other benefit of a pin connector is they are water resistant and better with dielectric grease. Terminal strip can work just as good if you use anti corrosive product and put a cover over it to keep stuff from shorting it out. |
Posted By: swilliams
Date Posted: April-12-2018 at 7:15am
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That would be an OMC motor most likely. Find an OMC service manual for that vintage(need model #) and it will give you the schematic. Finding the harness will be the hard part. ------------- 1976 Martinique,350 Omc. 1975 Glastron/Carlson CV16,115 Merc. |
Posted By: baitkiller
Date Posted: April-12-2018 at 11:55am
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Color codes are all the same. Brown / white will be the oil and temp alarm. Gray is tach Purple is switched power or ignition Red is unswitched power or dash feed Light blue is oil pressure tan is temp Pink is fuel guage Yellow / red is start circuit. Big orange is for an ammeter. Good luck Hope that helps. ------------- Jesus was a bare-footer............. |
Posted By: 8122pbrainard
Date Posted: April-12-2018 at 12:10pm
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Kerry, Were you able to determine the cause of the meltdown? Hopefully you have plus, with the rewire, I highly recommend adding overcurrent protection. Also, OMC liked to add a diode in the wiring harness. Check for one. It prevents draining the battery when the engine isn't running. ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: Gravel_Laker
Date Posted: April-12-2018 at 2:07pm
| Thanks you all. Good Info! |
Posted By: shierh
Date Posted: April-12-2018 at 2:09pm
| interested in the Diode in the circuit. can you provide a basic schematic showing where it would be placed? |
Posted By: Gravel_Laker
Date Posted: April-12-2018 at 2:11pm
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I bought the boat like this...it's going to be a project. I looks to be critter damage as you can see tooth marks. |
Posted By: Gravel_Laker
Date Posted: April-12-2018 at 2:36pm
| I really don't know yet. I just found a schematic for all the engine wiring. |
Posted By: shierh
Date Posted: April-12-2018 at 4:17pm
| Was hopeful that 8122pbrainard would provide a simple schematic. I know how a diode works but don't understand how it could prevent battery drain when switch is off. A diagram could be helpful to explain. I usually bounce this stuff off of "the word". |
Posted By: 8122pbrainard
Date Posted: April-12-2018 at 5:03pm
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http://www.correctcraftfan.com/forum/forum_posts.asp?TID=9962&title=alternator-external-diode" rel="nofollow - Thread on back feed diode http://www.correctcraftfan.com/forum/forum_posts.asp?TID=39119&title=fusible-alternator-link" rel="nofollow - #2 thread on omc diode Diode:  Kerry, On the diagram you found, does it show the diode? It may be labled as a "fuse" or "fusable link" ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: shierh
Date Posted: April-12-2018 at 5:44pm
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So if a switch had corrosion in it and was completing a circuit while it was in the off position or other corrosion was grounding a circuit t then this device would not do a thing? Diode used in alternator to make ac current go one direction to make it a DC charger is one thing but what good would it be outside of that? Guessing this is why you don't see this component in other boat circuits outside of a galvanic isolator for safety ground on a shore power hook up. |
Posted By: 8122pbrainard
Date Posted: April-12-2018 at 6:49pm
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Steve, My understanding is OMC used the diode on some of their engines to control the diection of the DC preventing a backfeed. ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: shierh
Date Posted: April-13-2018 at 1:19pm
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Lost me there, not sure how you back feed a DC circuit other than reverse polarity and if that occurs the wire melts down instantly and fuse blows etc. Still don't see how it prevents battery from dying while switch is off. Guess ill consult "the word" |
Posted By: Duane in Indy
Date Posted: April-13-2018 at 11:15pm
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Don't hold your breath on an answer. I am as lost as you. Thought I understood diodes and fuse able links but guess not now ------------- Keep it as original as YOU want it 1978 Mustang (modified) |
Posted By: KENO
Date Posted: April-14-2018 at 9:14am
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The quote from Mustang Madness below tells where it's located (alternator output to battery) so the electrical flow only goes to the battery. If you have a bad diode or diodes in the rectifier assembly in the voltage regulator you would have a flow path from the battery to ground through the alternator when the engine wasn't running. Not a big amount of current but enough to discharge the battery overnight or over a day or two depending on how much flow there is. Not enough to melt wires You'd also have reduced charging capacity when the engine was running, because of the bad diode(s). A diode would stop the back flow.in that situation. and with a fusible link in the assembly you have overcurrent protection for the output wire in either direction of flow. Now if somebody like SWilliams, who I'm sure has an OMC manual from the mid 70's could scan and post a wiring diagram, it would gives plenty of info about that assembly like whether there is both a fusible link and a diode in there. The maintenance manual must have some info.  [QUOTE=MustangMadness] My battery stopped charging. I measure only 12.5v when running above idle. When running my amp meter (not a voltmeter) reads 0 or slight discharge. That ball device is on the output from the alternator to battery lead on the starter solenoid, not the vreg output to field.. It would make more sense to me if it were a fuse. I would include a pic of it if I were up at my camp. I will include in a day or 2. It looks like this ball  https://www.marineengine.com/newparts/part_details.php?pnum=OMC0383432" rel="nofollow - https://www.marineengine.com/newparts/part_details.php?pnum=OMC0383432 I found a new one on eBay  $20 delivered, can't beat it! I guess it is a fusible link of sorts. |
Posted By: swilliams
Date Posted: April-14-2018 at 9:58am
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Can do! Kerry, pm me your email address and I can email the wiring diagram if you like. Include your motor model number and I’ll see if it matches the different ones the manual covers. Regardless, the wiring should be about the same as mine. ------------- 1976 Martinique,350 Omc. 1975 Glastron/Carlson CV16,115 Merc. |
Posted By: KENO
Date Posted: April-14-2018 at 10:08am
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Hi Steve If you could e mail your wiring diagram to me too, I'd like to see it and I'm sure learn a little more about OMC's Also, what brand is the alternator ? e mail is keno439@gmail.com Thanks KenO |
Posted By: shierh
Date Posted: April-14-2018 at 10:12am
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Keno, good explanation. So it seems it is not a necessary component, only there if the internal diode within the alternator fails. So if the internal one fails would not the back up one get pretty hot? doesn't seem that an insulated diode would be able to cool down. Can diodes leak back just a little and not completely fail? if so then i see how this component could be useful. |
Posted By: KENO
Date Posted: April-14-2018 at 10:30am
Far from very knowledgeable on diodes, but I think they either work or don't work, no in between. The rectifiers usually have 6 diodes to magically turn the AC from the alternator into DC and they can fail individually. I think the external OMC diode would be sized for being able to handle full alternator output by itself. I'd say it's not necessary, but nice to have |
shierh wrote:Posted By: swilliams
Date Posted: April-14-2018 at 11:25am
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Prestolite ALK-6222A or 6222AY alternator. Parts book show that as a fuse and lead assembly. Fairly ugly assembly but it’s there to protect. My engine has it. 60 amp fuse. ------------- 1976 Martinique,350 Omc. 1975 Glastron/Carlson CV16,115 Merc. |
Posted By: 8122pbrainard
Date Posted: April-14-2018 at 2:02pm
Steve, I feel you are confusing a direct short which would be a positive to negative connection. Yes, that sure would blow a fuse but a positive to positive connection will not. Regarding a "back feed" and the diode, picture a water pipe with a water source at each end with a check valve in the middle . The check valve prevents water flow in one direction the same as a diode prevents current flow in one direction.. ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: KENO
Date Posted: April-14-2018 at 2:35pm
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So Steve,(Williams) since you have one....................... It's time to pull that off the alternator and test it to see if there's a diode in there and solve this mystery. Here's a link to testing a diode with a meter. In a nutshell, hook the meter leads up one way and then reverse the leads and compare readings. If there's no diode, you'll have continuity in both directions If there's a diode, you'll have continuity in one direction and an open circuit in the other. Depending on part numbers, OMC calls some of them a fuse and lead assembly and others a diode and blocking assembly. http://en-us.fluke.com/training/training-library/test-tools/digital-multimeters/how-to-test-diodes-using-a-digital-multimeter.html" rel="nofollow - link |
Posted By: KENO
Date Posted: April-14-2018 at 7:02pm
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For somebody named Steve who might want a spare one of these fuse and lead assemblies check this link on EBAY..( I remember your hunt for black Mallory YL distributor springs) Don't know if it's the same part number since you didn't give one but I bet it is. I bought one just because I felt like it so I could see just what it really is OMC 383432. is the part number I figure it'll come in handy on most any alternator. There are some a little cheaper than the one I linked, but I like the place in the link, having bought stuff from them before You can also find them for a whole lot more money if you so desire. . https://www.ebay.com/itm/New-Evinrude-Johnson-OMC-Fuse-Lead-Assembly-Part-383432/302206021573?epid=1739565475&hash=item465ce1efc5:g:vdsAAOSw241YiSKX&vxp=mtr" rel="nofollow - link |
Posted By: KENO
Date Posted: April-18-2018 at 5:49pm
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Well, the mailman left me a package today. My OMC part showed up so I figured I'd figure out what's inside the ugly blob of epoxy. Took the multimeter and it conducted in both directions then also put it in the supply to a 12 volt light in both directions and the light lit up both ways so....................ain't no diode in there Now I gotta decide what to do with this thing. I could keep it hanging around, I could use it as OMC meant as overcurrent protection for the alternator output wire or I could cut the wrapping off and see why OMC and now Bombardier charged a fairly outrageous list price of about 55 bucks for it. They're a whole lot cheaper on EBAY after nobody has bought one for the last 20 years or so and it's taking up shelf space. 
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Posted By: 8122pbrainard
Date Posted: April-18-2018 at 6:13pm
Ken, I think you should send it to Billy as he's the one that started the whole diode concept!!  ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: SNobsessed
Date Posted: April-18-2018 at 6:37pm
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Can you return it? ------------- “Beer is proof that God loves us and wants us to be happy.” Ben Franklin |
Posted By: Gary S
Date Posted: April-18-2018 at 7:25pm
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Sorry no returns on electrical parts ! 😮 ------------- http://www.correctcraftfan.com/diaries/details.asp?ID=1711&sort=&pagenum=1&yrstart=1966&yrend=1970" rel="nofollow - 69 Mustang HM SS 95 Nautique Super Sport |
Posted By: KENO
Date Posted: April-19-2018 at 9:02am
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I think I'll hang it right in plain sight at the workbench as a reminder of how good the internet can be at spreading bum dope.at times. |
Posted By: shierh
Date Posted: April-19-2018 at 4:38pm
| So after all this it has nothing to do with Back Feed. Nothing to do with draining battery or anything else, its a simple fuse? Thought everyone used a breaker, guess OMC guys wanted to be different. Make more money selling fuses I guess. |
Posted By: KENO
Date Posted: April-19-2018 at 7:43pm
The thing is just a fuse. Now if you look at a PCM wiring diagram they use.....................nothing on the alternator output. Straight from the alternator to the output side of the main breaker, no protection for the alternator output wire if it was to become grounded between the alternator and the breaker,other than the wire being sized to handle full alternator output. And if you have rectifier diode issues like mentioned a while back, you can drain the battery back through the alternator overnight. The flowpath is from the battery to ground through the rectifier assembly and the amount of current depends on the failure. The OMC fuse will do nothing to stop this slow discharge. And also depending on alternator brand and style, you can have issues where you turn the key off and the engine stays running especially with a 3 wire AC Delco swap in place of a different alternator. It backfeeds through the excitation line and the coil stays powered till you rip the wire off or you choke it till it stops or if you're feeling real lazy, you let it run till it's out of gas An external diode or a properly sized resistor comes with many of the AC Delco swap kits for this reason. |
Posted By: shierh
Date Posted: April-20-2018 at 11:07am
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So if you have a rectifier issue in your alternator and you have an external diode as a safety then you will not know you have a problem, I would want to know there is a problem. |
Posted By: shierh
Date Posted: April-20-2018 at 11:11am
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Im also guessing that if your boat is set up with amp meter instead of volt then you would notice a significant discharge when key is off, am I correct? I changed mine to volt meter when I re did the electrical. Now I am second guessing the decision. Mine would be easy to re wire however since I used a positive and negative buss bar under the dash. |
Posted By: KENO
Date Posted: April-20-2018 at 11:28am
You'll know it when the alternator is not putting out it's normal voltage and the voltmeter starts dropping as the battery gets run down. And if you don't notice that, the boat will eventually quit or if you turn it off the next tijme when you go to start it the battery will be dead. or really run down. |
Posted By: KENO
Date Posted: April-20-2018 at 11:35am
I think I'd call it more of a minor deflection on the meter that you may or may not even notice. You done it now though Steve, you mentioned the word ammeter and left the door wide open for Pete to show up and proclaim his undying love for ammeters
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Posted By: shierh
Date Posted: April-20-2018 at 12:11pm
| My dad who we call The Word, is an ammeter fan. He wanted me to re wire in that manner. dads 88 but I can say he has forgotten more than most will ever know. Aerospace engineer that actually did write the book or at least a chapter in an engineering manual. |
Posted By: 8122pbrainard
Date Posted: April-20-2018 at 7:02pm
Steve, It sure sounds like your dad is a very intelligent person. Gain as much of his knowledge as you can. There sure are times that I think back and wish I had listened to my father more than I did. ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: Julie
Date Posted: July-10-2018 at 2:04pm
I have an 86 Ebbtide OMC 4.3 V6 with an external diode wired to the alternator that has failed. Boat will start but not shut off  . Where can I find a diode. I do know that it is the same engine as a 86 Astro Van! Help!!!!------------- Jules |
Posted By: KENO
Date Posted: July-10-2018 at 2:17pm
| A picture is worth a thousand words and a it's lot easier to see just what you need |
Posted By: Julie
Date Posted: July-10-2018 at 2:23pm
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Can't post picture because the diode burnt up..I guess over time. In line diode with shrink tape over it going to the alternator. ------------- Jules |
Posted By: KENO
Date Posted: July-10-2018 at 2:44pm
| How about a picture of the alternator (from the rear) or if there's a tag on it with the brand that would be helpful too. |
Posted By: Julie
Date Posted: July-10-2018 at 4:44pm
  The photo take from the back has the heat shrink attache to the purple wire where the external diode was! ------------- Jules |
Posted By: KENO
Date Posted: July-10-2018 at 5:38pm
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Well, those pictures give quite a bit of information First I'm sure it's a Delco Remy 3 wire alternator mostly because it says Delco Remy on the back. Second that's not a marine alternator because there is no spark arrestor screening on the back of it. The marine ones have the screens in front (behind the fan) and in the back. The ones in the back are plainly visible and yours doesn't have any back there. Somebody probably replaced it sometime in the last 32 years. It's an explosion hazard. You can find a marine rated Delco Remy 3 wire in the link below at a reasonable price. As far as finding a diode, I'd look for a 5 amp diode at an electronics website or on EBAY they're easy to find. They're a buck or two each. Did you have to pull that wire off to stop the engine? Usually when a diode dies you get an open circuit and in this case an open circuit on that wire wouldn't have prevented shutting off the engine. If everything melted and fused together, then you'd have problems shutting it off. It looks like somebody's homegrown diode job from what I can see.(Looks like somebody crimped a spade connector onto the diode wire that's visible if I'm seeing the second picture right) I'd get the marine alternator as part of fixing this. Kinda a long answer for "where can I find a diode?" and maybe not what you wanted to hearhttps://www.dbelectrical.com/products/delco-marine-alternator-mercruiser-3-wire-63-amp-10si.html" rel="nofollow - link |
Posted By: Julie
Date Posted: July-10-2018 at 9:46pm
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Keno, Guess I am buying a alternator. Do I need a diode too? This old boat is functional and I hear the 4.3 V6 is bulletproof. This is my second I.O. and I ws not aware that alternator was not marine. Better to be safe then sorry. Pulled the wire to kill the engine, the re started with the wire off and she shut right down. ------------- Jules |
Posted By: Julie
Date Posted: July-10-2018 at 10:01pm
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Keno, Are you 100%sure that is the correct alternator? I appreciate your help!!! Thanks!!!  ------------- Jules |
Posted By: Julie
Date Posted: July-10-2018 at 10:10pm
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Can you be a little more specific about where to get the correct diode??? Thanks! ------------- Jules |
Posted By: KENO
Date Posted: July-10-2018 at 10:45pm
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If you want something that's pretty foolproof as far as wiring, you could get a 1 wire Delco alternator. The 1 wire only has the output terminal and you would hook your big orange wire there. The sensing and excitation wires that go to your present alternator just get taped off and hooked to nothing It's self exciting and senses output voltage right at the alternator. It has some disadvantages like you need to initially rev it to about 1000 rpm's for it to excite itself every time you start the boat, then it's good till the next start even if you go down to idle speed. For a boat with no big loads it works fine, quite a few people here have used them A lot of boats came with them as standard equipment over the years including some OMC's If you have a big honkin' stereo with a half dozen giant speakers the 3 wire would be better You'd have no need for a diode either Maybe some other people will weigh in with their opinions. DB electrical, the same place as the link in the previous post sells them too, for about the same price as the 3 wire. You'd want one with the same size pulley you have now.. |