best way to clean a multi plug on my engine harness in my boat.

Discussion in 'General Electronics Chat' started by vivelo, Nov 8, 2015.

  1. vivelo

    Thread Starter New Member

    Nov 8, 2015
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    hi all,

    I have a short in my harness as I'm getting voltage when I shouldn't and not enough voltage when I should, it doesn't change. I have a 12v dc system on my boat. I think I have found the fault to be a multi pin connector in the harness. It is greasy in there and i didn't help the cause spraying wd40 thinking it would because the voltage/short increases.

    it's a plastic connector, approx 30 pins. My question is how can I clean it safely, remove any corrosion and then protect it.

    I'm not sure why its faulty or what's caused it, I can only think as the boat has sat for a number of year and the small amount of water in the bottom has condensed on it. The connecter sits in a bracket on top of the engine, and during warmer times and close proximity to the cold engine and bracket has cause moisture to get in.
    according to the wiring diagram, the wire which is causing me a problem is wired direct from the ignition switch to the fuel cut off solenoid. I have disconnected both ends and still get a voltage of 5v, though this changes daily as yesterday it was 7v, disconnecting the connector this disappears and is 0.7v.
    I'm 60% sure the connector is the problem, but how is best to clean without poking it so not to damage the pins etc.
    I have read about radio ops using vinegar and salt, then neutralised with soda. Would dipping it into a solution of something be my best option and if so, do you recommend something. I'm in the UK, so uk brands only please as we dont get the good stuff over here.

    thanks in advance and let me know if you need more info.
     
  2. blocco a spirale

    AAC Fanatic!

    Jun 18, 2008
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    Are there any electronic devices connecting via connector or is it just 12V electrical stuff e.g. motors, relays, lights, solenoids etc? It may be that, if you're measuring the voltages with a digital multimeter you are seeing voltages caused by tiny currents leaking between pins due to the environmental conditions but the current will be so small it won't affect the function of the electrical equipment. An analogue meter or test lamp can be more useful as they require current to operate so won't be prone to giving false readings.

    If you are uncertain about the quality of a connection passing through the connector, bypass it by connecting a wire(s) directly between the devices.
     
  3. vivelo

    Thread Starter New Member

    Nov 8, 2015
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    the solenoid is wired direct, no fuses or relays. There are other relays for things, bur the wire is direct and only breaks are the multi pin connectors. I've got the wire disconnected both ends and was still getting the voltage, but it stopped when I unplugged this one connector. So it has to be in there.
    I'm going to the shop to buy some vinegar, salt and son bio soda to dip them in and rinse. Read somewhere that's how some clean wires etc.
    I've only got a multi meter, but after spraying wd40 in the connector, the voltage increased when I was hoping it would drop. There is nothing connected to either end now and still have the voltage, disconnect the multi plug and the stray voltage goes. So its got to be the multi pin connectors.
    any better cleaning methods would be appreciated!
     
  4. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    Please
    - Post a clear and close-up photo of your connector
    - Post a picture/scan of the wiring diagram.
    - Let us know what type of problem you are having with the boat (besides being able to measure a voltage when you don't expect the voltage greater than zero from a dirty connector).
     
  5. vivelo

    Thread Starter New Member

    Nov 8, 2015
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    I've only got a pdf of the manual and my phone as I on the boat, so no way of posting just the image. I've just bought the vinegar etc to try. It will be dark by the time I get back and will do photos in the morning.
    the actual problem started because the engine would not start, the normal mechanical check are done. It was either the fuel cut of solenoid or injector pump stopping it working. Before I was going to strip it I tested the wiring as that's easiest and found the fault. I was expecting 12v, but got 1.7v. I checked the other engine and that was 7.2v, still below the 12v but the engine started, so it must be enough power to open the solenoid. I sprayed wd40 in the conector and th voltage went up?!? That was on the engine with 1.2v.
    disconnecting the plug made the voltage almost go, but still got .4v or abouts on the male and female. So I'm pretty sure the plug is at fault. I'm assuming that as the boat stood unused form few seasons that the bit of water in the bilge and sun caused condensation as this connector sits n a bracket directly on top of the engine.
    I'm going to clean it tomorrow and see.
     
  6. vivelo

    Thread Starter New Member

    Nov 8, 2015
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    sorry for the poor english, after two sentences i cant see what ive typed on my phone.
     
  7. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    The problem with WD40 is that it has a lot of oil like substances in it:
    https://en.wikipedia.org/wiki/WD-40
    Oil is an isolator and will reduce the current in the plug connections.
    You must get rid of the oil. you could try an alcohol based cleaner.

    Bertus
     
  8. MaxHeadRoom

    Expert

    Jul 18, 2013
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    To prevent the ingress of moisture after cleaning, smear the connector itself with Dielectric Grease. Moisture preventer. Available at any automotive parts store.
    Max.
     
  9. blocco a spirale

    AAC Fanatic!

    Jun 18, 2008
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    I would avoid using anything corrosive because it could be drawn up into the wires where it will eat through the copper.
     
  10. vivelo

    Thread Starter New Member

    Nov 8, 2015
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    how else can i clean it? I dont want to bend the pins or put files in the holes stretching them. Volvo penta wants a lot of money for a new harness.
     
  11. wayneh

    Expert

    Sep 9, 2010
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    I would start with brake cleaner spray to remove oils and grease. Be very careful to avoid over-spray onto any other surfaces, and check first with a small drop of the cleaner to verify it will not soften the plastic of the connector or wire insulation. I've never seen that happen, but the stuff is a solvent.

    The brake cleaner will not touch any corrosion. I don't recommend salt and/or vinegar for that, although it will remove the corrosion. Vinegar is at least volatile and will eventually evaporate, but the salt will not. Instead there are spray contact cleaners that are designed for exactly this purpose. Unfortunately they are expensive and I have not personally used any for that reason.

    I second Max's recommendation to use dielectric grease. I've had good luck using it to clean up - and then protect - contacts that looked pretty bad. Trailer hookups can look pretty bad in the spring, for instance, from grit and road salt and such. The dielectric grease can really help with that. The grease does not itself conduct, but it helps clean and protect the metal so that a good connection can be made.
     
  12. vivelo

    Thread Starter New Member

    Nov 8, 2015
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    I cant see any other way of cleaning it, brake cleaner is not good on plastics and for the initial clean to remove the grease I plan to dip in warm soapy water. I use white vinegar for lots of cleaning, I'm not sure why to add salt, but the vinegar salt mix is neutralised with the second wash of bicarbonate of soda and a fresh water wash off. It was on a diy website......
    if you can tell me the product to buy off the shelf I would rather buy something that's ready made, but I cant find anything.
     
  13. vivelo

    Thread Starter New Member

    Nov 8, 2015
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    Manual attached. Mine is the late version, page 41,42.
    The wire in question runs from the key switch and is the purple wire to fuel stop solenoid. Nothing in line except the multi connectors. So with the purple wire disconnected at the key switch and solenoid I got voltage, when connected I still only have that voltage and not 12v.
     
  14. vivelo

    Thread Starter New Member

    Nov 8, 2015
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    Uploaded the manual below.
     
  15. debe

    Well-Known Member

    Sep 21, 2010
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    I would remove the conector & join the wires individualy. Then seal them as these conectors are a pain. To get the engine going in an emergency just jumper 12V to the pump shutoff solenoid. The boat I worked on in my avatar above the seals head had 2 x 250HP Volvo diesels in it.
     
  16. shortbus

    AAC Fanatic!

    Sep 30, 2009
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    I'd try electrical contact cleaner before the vinegar or brake cleaner. Spray both sides of the connector then plug and unplug a few times to get the corrosion loose. Then repeat, then respray and reconnect . If every thing checks OK, then apply the dielectric grease to stop further corrosion.
     
  17. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    Brake cleaner comes in green can and red can. Green can (esters and alcohol) will not damage the wire insulation like the red can (tetrachloroethane or dichloromethane).

    Acetic acid solution (vinegar) will make everything worse.
     
    shortbus likes this.
  18. KeepItSimpleStupid

    Well-Known Member

    Mar 4, 2014
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    Can you get any spray foam engine cleaners? Brake pad cleaners? Do avoid citric acid.

    In the US, I would use SuperClean. http://supercleanbrands.com/products It doesn't like painted surfaces or glass.
    It's OK only if thoughoughy rinsed. It does etch glass. I had to buy another product that fixed that.

    Dielectric grease is recommended.

    Very severe corrosion might require replating or replacing the pins.
     
  19. DNA Robotics

    Member

    Jun 13, 2014
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    I agree. Soldering with shrink tube is best. Bare butt splices with shrink tube is second best. Butt splices with shrink tube on them will work if you don't pierce the shrink tube when crimping.
     
  20. vivelo

    Thread Starter New Member

    Nov 8, 2015
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    thanks everyone for their replies, before I went to clean them I was checking the the ignition barrel when disconnected. I was seeing if there was any resistance etc and then discovered the solenoid is energise to stop, opposite to a car (if it was this way on a car you could just bump start it without the key).
    so I'm back at square one, the stray voltage is still there, though lower, but when the solenoid is activated in getting full power to it.
    I'm now hoping it a case of the rubber bung on the end of the solenoid that has stuck or come off. Time to find a 24mm wrench and get it out.
    looks like its a mechanical problem!
     
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