Re: [omc-boats] Wiring Sub Harnesses

From: LShuster \(lib1\) <lib1@...>
Date: Wed, 8 Jun 2005 12:31:46 -0600

If wiring seems complicated, it sometimes helps to break it down, and to try & understand what the basic sub-harness functions are. This wiring schema-design philosophy is fairly common across the entire range of OMC-powered 4-stroke I/O boats. There are some minor differences between years and models but they are relatively minor. The 2-stroke V-4's are quite different on the motors themselves and use a slightly different motor-to-dash cable assembly from their more common 4-stroke brothers. For easier service, that dash/switch panels were modularly connected in later models (pos-'67). 1) Battery Cable Assembly (easiest of all to reproduce) Red (+) runs from battery to Starter solenoid, Black (-) to engine ground
2) Terminal block (usually 4-post) located in engine area, sometimes there may also be one under the dash.
3) Fuse Block (located under dash) usually has both pos and neg feed inputs with 9 fused outputs and ground buss terminals. Uses common "glass-type" AGC fuses. Fuse/circuit positions are lableled: Spare, Pump, Horn, Cig(ar), WW, Inst(rument)., Runn(ing), Int(erior) , Spare.
4) Dash Panel Cable Assembly. This cable connects to your instruments, warning lights, and switch gear or one end. The other end has two large multiple-pin connectors that hook up to the motor-to-dash cable.
5) Motor-to-Dash Cable Assembly Bow-end connects directly to the ammeter, while another connector hooks up to electric shift control, two large connectors hook up to dash panel connectors. Note: on electric stringers there is no default, "fail-safe" gear engagement system. Make sure your shifter switch and wiring are working properly. Loss of power to either forward or reverse coils could ruin your day. On the stern-end there are two, large connectors: 1) hooks up to engine functions, and 2) connects to the tilt solenoids and bilge pump/blower. There's typically a stern light connector and then some heavy, 8 ga wires connect the ammeter to the terminal block (# above).
6) Tilt/Bilge/Shift Harness/Cable plugs into one of the large connectors from the motor-to-dash harness. Other ends run to the tilt Up and tilt Down solenoids, the tilt motor connector, the shifter control harness and the bilge pump/blower connector.
7) Engine Harness/Cable this also plugs into it's own large connector from the motor-dash harness. The engine items it is wired to include: Alternator, regulator, coil, ballast resistor, water temp sensor, oil press sensor, starter solenoid and starter motor. Don't overlook the separate 8-10 ga black wire running from engine ground back down to the terminal block running. It's interesting that that last two cable (#6 and #7) are considered part of the engine and are not listed in my Sportsman boat parts book. That probably means that you could pull either of those assembly from just about any 64 - 77 electric stringer 4-stroke OMC and might plug-and-play. Chances are it won't be in any better shape than the one in your boat now, however.

Hope this is helpful. If your want further clarification, take a look at the wiring diagram(s) that Phil posted and this will make a little more sense. Sorry my scanner can't do it in one big continous pass.

Lee Shuster
Salt Lake City

----- Original Message -----
  From: lib1@...
  To: omc-boats@...
  Sent: Wednesday, June 08, 2005 8:17 AM
  Subject: Re: [omc-boats] Wiring

   Not only can electrical problems be an annoyance (mostly) they can leave you stranded, or worse, sometimes lead to fires, so this a good topic for discussion.

  Tom's and Lee's different approaches to fixing wiring harnesses both have their places. I've done it both ways on a number of cars and boats. Tom's approach is more time consuming but is ultimately better beacuse with Lee's approach there's more points of potential failure introduced in the electrical continuity path. But Lee's approach is more commonly performed by individuals and shops and can focus on an immediate problem area, typically with the wiring remaining in the vehicle.

  Getting, understanding and verifying the wiring diagrams is essential. Sometimes on 40-year old technology someone has previously modified a circuit or used a different color wire. While heat is not the enemy (as it is in underhood autos) corrison and moisture can and do take a toll on boats. OMC used to make a tube of electrical connector "grease" that kept mositure out of the connector and reduced the chance of oxidation or corrosion. You don't need the OMC stuff, auto parts and electrical supply places carry it under different names.

  One thing I have learned, it's always best to pull the harness completely out of a vehicle and then lay it out and tag the connectors. This makes it much easier to measure lengths and to access, inspect and replace connectors and pins. Take pictures of the connections and make notes before removal if your unsure of how it all connects. I find I can take my time and do a much better job on the workbench, rather than curled up under the dash or reaching under or across a motor.

  The process that Tom K. describes can be done at home, but I would add another tip: Start by practicing on a small sub-section, perhaps involving something non-critical like nav lights; rather than the tilt or bilge blower/pump. Also, for anyone that's afraid to do this yourself, I know of a professional shop (they normally manufacture airbag harnesses) that will make a completely new vehicle harness, using your old harness as a pattern. But be prepared to fork over big money to have someone else to it right -- on the order of $900 to $1200 for parts & labor for a complete wiring makeover.

  Lee Shuster
  Salt Lake City
    ----- Original Message -----
    From: Thomas Klauber
    To: omc-boats-digest@...
    Sent: Tuesday, June 07, 2005 7:30 PM
    Subject: [omc-boats] Wiring

     This message is to all but especially Jay. Here is the way to redo the wiring harness - it is not the cheapest but is a total redo. First get a Clymer and a Seloc manual which you really should have already. Find a used OMC Stern Drive Service Manual for your year and horsepower boat on ebay ( easier said than done but patience will pay off ). You will find wiring diagrams in all 3 of these publications and each will show the wiring in a slightly different format but with enough study you can confingure what is supposed to be on your particular boat. The OMC edition shows the wiring in color. I have looked forever for used and or new wiring harnesses for the older boats on ebay and they just dont exist and I did find one used one that I bought and it was in pretty bad shape but I was able to use the voltage regulator which you can get aftermarket anyway. Use your old harness for a template too. Mine was totally toasted. You cut the wires off a little above the entrance to the plug. There are 2 sizes of pins in the plug. You work each wire with its pin out the back of the plug through the smaller hole. The pin is soldered and pressed on the wire end so you will have to cut off the pressed part - it is impossible really to undo the pressed part. You do not want to damage the pin cause you are going to re-use it. If the pin is corroded (like 2 of mine were) then you will have to improvise a new pin. Dave Losvar at SeaWay Marine in Seattle has the terminals for the other ends of the wires if you want to get original. He even has the flag terminals for the temp and oil senders ( for the idiot lights ). He has the knife terminal disconnects too, otherwise improvise. MAKE SURE YOU USE MARINE GRADE WIRE AND TERMINALS. You buy Marine Primary Wire from West Marine which sells the proper grade and color wire to rebuild properly and they sell it in smaller than 100 ft. spools so you dont have so much left over. I would not recommend using all one color and grade (unless you are selling the boat). Remember every connection you put in the harness is a potential Sunday afternoon breakdown. You will end up buying 10 or so small spools of wire all different sizes and colors depending on the infomation you gather from the manual. You get a nice wire stripper and solder the wire into the pin through the open end which you may have to drill to get inside, youll see what I mean when you get the pin out and the wire off - the pins are hollow. You basically are reattaching the new wire to the old pin and you slide the pin and wire back into the plug. It is not easy to slide the wire back through the holes left in the rubber plug but if you use the same size wire as original it will all fit back in place totally like new. I used a small wire to go through the hole and pulled the wire and plug in from the front of the plug using a little lubricant. Position the pin back into the plug the same depth as original. Do this for each wire. When they are all in then put a little black silicone sealer in the plug end to sort of set the wires. They can be pulled out again but take a lot of effort and the plug clamps together and they cummulatively will withstand a lot of pull. You wrap the harness in harness tape like the original and reinstall. You will need to measure each wire length carefully so the fit will be proper. Save stuff like rubber boots and use them again. This is the basics of what I did and it works well ( so far ). Take your time and measure and remeasure and check for electrical continuity often. When you are finished you will know that harness like the back of your hand. It takes a long time but is worth it. Do it this winter. Take the warness off when you put the boat up and get to work.Take lots of notes. A temporary fix is to put liquid electrical tape on the wires to stabilize and insulate them. Once the insulation falls off they will corrode and fall apart. West Marine also sells Liquid Elec. Tape. Good luck - hope this helps. TK

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Received on Wednesday, 8 June 2005

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