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Ignition Wiring Question

Discussion in 'Mid-Size Boats' started by Kevin S, Feb 4, 2017. Add this thread to a FAQ

  1. Kevin S

    Kevin S

    Joined Dec 7, 2015
    8 posts, 1 likes
    Catalina 270
    US Bradenton, FL Bradenton, FL
    Wondering if anyone can shed some light on this for me:

    I have a 1993 Catalina 270. I went to start the engine the other day and after it cranked 2 or 3 times, the instrument panel totally died. Since then, the instrument panel won't light up and nothing happens when I turn the key. Batteries are fully charged and all of the other electrical systems on the boat are still working.

    Engine is a Perkins M20, and as far as I can tell the ignition wiring follows the attached wiring diagram exactly.

    My knowledge of electrical systems isn't too advanced (I've read Don Casey's book on the subject, as well as lots of internet stuff). I browsed through Stu Jackson's Electrical Systems 101 (http://c34.org/bbs/index.php?topic=5977.0), but unfortunately the link to "Engine Starting Issues - that pesky negative ground connection" just led me back to the C34 home page. Anyway, I broke out the multi meter and this is what I've found so far. If anyone is able to make sense of it or offer any advice, I would be most appreciative.

    Findings:

    -When testing the brown power wire to the ignition switch, this is what I find: It has 12+ volts when using any of the ground wires in the system when the switch is off (no key, or position P or O). With the switch in position 1, 2, or 3, it has about .5 - 1 volts when using any of the same ground wires. When using an independent ground (from the fuel gauge, which is wired separately and uses a different bolt on the engine as it's ground), I measure 12+ volts in all switch positions.

    -The tab on the ignition switch where the brown power wire attaches (marked "30" on the diagram) has continuity with each of the other tabs on the ignition switch when the key is turned to the appropriate position.

    - Using any of the ground wires in the system, and testing the voltage at the various tabs on the back of the ignition switch, the tabs each show about .5-1 volt when the key is switched to the appropriate positions. I tested this with everything hooked up as well as with each tab individually (i.e. when I tested the white wire, it was the only one plugged in, same for brown/red and white/red) and got the same results.

    - When I repeated that test with everything unplugged from the back of the switch (except the power), I got 12+ volts between each tab and any of the ground wires in the system, with the key turned to the appropriate position.

    -When I hooked everything back up and repeated the test again using an independent ground, I got 12+ volts at all tabs with the key in the appropriate position.

    -When I put the volt meter's positive lead on any ground wire in the system and the negative lead on the independent ground (fuel gauge), I measured 12+ volts with the key in positions 1, 2 and 3.

    -Some resistance measurements:
    system ground to independent ground - 20 ohms
    white wire at ignition switch (goes to other instruments) to system ground - 5 ohms
    brown/red wire at ignition switch (goes to glow plugs) to system ground - 45 ohms
    white/red wire at ignition switch (goes to starter solenoid) to system ground - 1.5 ohms

    -I'm pretty sure the wiring is original (24 years old), and the boat has lived in the water year 'round in Florida for all of that time, so I know there is some degree of corrosion and resistance in the wires.

    All of this leads me to believe that power is leaking to the ground wires when the ignition is turned, and therefor there is no electrical potential to light the instrument panel, flip the relay, or activate the starter solenoid. Again, I'm still trying to learn about electrical systems, so that belief may be way off.

    Someone on another forum suggested that it might be an open ground due to a loose connection. I went down to the engine and gave a tug on all of the wires in the 10 pin connector and nothing seemed loose. I did the same at the connector behind the instrument panel and everything was solid there too. I'm not sure, but I think the fact that I can measure 12+ volts between the switch's power wire and the system ground wires (although only with the switch off) rules out the open ground??

    Any other problems anyone can think of that might explain this? Is my "power leaking to ground wires" theory just a simpleton's misconception of what is happening here?

    Also, because the engine cranked a few times and then everything died suddenly, it leads me to wonder if in addition to the above problem, I may have fried some other component of the system.

    Thanks as always for any knowledge you can throw at this one.

    Kevin

    P.S. Another thing I found that really baffled me was that when I unplugged the connector down by the engine to check the contacts, I measured 12 volts between the brown power wire and the ground wire on both sides of the disconnected plug. In other words, on the half of the connector attached to the engine (and grounded to the bolt on the engine) I measured 12 volts between the power and ground contacts. The part I can't figure out is when I tested the same brown power wire with the ground contact on the other half of the connector (the one that runs back to the instrument panel), I measured 12 volts again. That confused me because the other end of that ground wire is just connected to the instruments in the panel.
     

    Attached Files:



  2. kloudie1

    kloudie1

    Joined Nov 6, 2006
    7,316 posts, 286 likes
    Hunter 34
    US Mandeville Louisiana
    Sounds like a classic bad connection.. Get some 220 grit (not super critical but close to that #) Clean all the connectors in the multi-pin connectors.. male and female.. The female ones, you can roll a small piece of paper to fit in the hole.. a small wire brush works as well if ya can find one small enough. something like this, maybe smaller..
    http://www.ebay.com/itm/Brass-Tube-Cleaning-Brushes-manual-small-diameter-4-pack-/251383310924
    Critical if using brush to have metal bristles..
    Disassemble the engine ground leads and clean.. it can be a terrible connection and still be tight..
    It is not unusual for a bad connection to heat enough during use to make it go mostly open.. so as it was cranking, it was heating (very small local area) and carburizing the gook in the bad connection, making it worse. Happy hunting !
     


  3. Stu Jackson

    Stu Jackson

    Joined Feb 26, 2004
    19,446 posts, 352 likes
    Catalina 34
    US Maple Bay, BC, Canada
    Kevin, part of that Electrical 101 is a link to Critical Upgrades. Take a look at that link, too. It's a connection, somewhere, most likely in the wiring harness, or the fuse to the starter solenoid from the ignition switch.
     


  4. Calif. Ted

    Calif. Ted

    Joined Jun 8, 2004
    1,952 posts, 55 likes
    Catalina 320
    US Dana Point
    I just got off the boat and I'm too tired to make sense of your findings, however from your description: There is a 20 or 30 amp ( I forget which) inline fuse taped into the giant wad of main wiring harness on top of the engine. This fuse holder is a cheap POS, the fuse doesn't blow but the connections get messed up. When electrical contact is lost in that fuse holder the engine instrument panel goes dead. First time it happened to me the engine was running, instruments went dead, engine kept running but when shut down would not restart. This was on a '94 270 with Perkins.
     


  5. Kevin S

    Kevin S

    Joined Dec 7, 2015
    8 posts, 1 likes
    Catalina 270
    US Bradenton, FL Bradenton, FL
    This seems like an easy enough thing to start with in the morning. I'll report back on how it goes.

    Stu - as always, the amount of resources you have cataloged is awesome! I read through the wiring harness thread on Critical Upgrades, as well as Maine Sails's article on wiring harness upgrades. I don't have the ammeter, and I don't think my alternator is wired through the panel, but based on what I've read in those threads/articles, I'm at least going to get rid of the trailer plugs, which I suspect are culprits in this problem anyway. Also, my wiring diagram doesn't show a fuse to the starter solenoid from the ignition switch, but I'll take a look and see if there is one is there.

    I'll take a look for that too.

    Thanks for the responses, guys. The help is truly appreciated.
     


  6. Ralph Johnstone

    Ralph Johnstone

    Joined Jan 4, 2006
    2,372 posts, 219 likes
    Hunter H-310
    CA West Vancouver, B.C.
    Follow kloudie1's method and grease all electrical connections (metal surfaces only) with a synthetic grease such as SuperLube to avoid a repeat of the same corrosion in the future. Also makes the connector come apart easily, years down the road.
     


  7. LeslieTroyer

    LeslieTroyer

    Joined May 20, 2016
    906 posts, 183 likes
    Catalina 36 MK1
    US Sammamish, WA Everett, WA
    Please don't use sandpaper ( or erasers or other abrasive) on electrical connections. You'll remove the metal that is a good conductor and corrosion resistant. Use contact cleaner or replace the connector.
     


  8. Kevin S

    Kevin S

    Joined Dec 7, 2015
    8 posts, 1 likes
    Catalina 270
    US Bradenton, FL Bradenton, FL
    Thank you for all of the replies. I got the engine started today!

    Nailed it. It did indeed turn out to be a bad connection. The battery ground wire, where it attaches to the engine. It really looked clean and tight, but when I took it off, cleaned it up, and put it back, it made all the difference. The frustrating thing is that the first thing I checked when this happened was the battery connections. I just didn't look close enough. The corrosion was all out of sight, but it was there.

    I still don't really understand how that explains what I found with the multimeter though. I was sure it was some funky, unique problem. But I guess I'm just another person in a long line of people who simply had a classic bad connection.

    Thanks again!
     


    kloudie1 likes this.
  9. Stu Jackson

    Stu Jackson

    Joined Feb 26, 2004
    19,446 posts, 352 likes
    Catalina 34
    US Maple Bay, BC, Canada
    Rather simple: unless there is a load on the circuit, all looks well. You're not the first, nor the last, with this issue.

    Good work on your part. You asked, you listened, and you made things work. BINGO!
     



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