Question regarding 12v forward cabin lights wiring

[Davee]

Hello All,

Let me preface by writing that this is my first post, and I'm doing my best to follow any and all rules and also tried to search as much as possible before posting my question. The question is in regards to my (new to me) 1987 C34 #494.

While preparing to wire in new forward cabin LED lights I came across an extra wire I was not expecting going into the old lights and seemingly soldered right into the old halogen light circuit board. I examined the 12v wiring diagram that is in the manual, and am somewhat confused why there is an extra wire...

I've attached some photos:

Photo 2879 shows the three wires (on the starboard side forward cabin halogen light) going to the light.

Photo 2887 shows the blue and black wires connected directly to the light circuit board while the red wire carries on through to the switch.

I've also attached the manual page I've referenced above.

The manual says there should be a blue and a black wire, and that on the port side I might expect to see a red wire passing on by to go to the forward navigation light (port light looks the same as the starboard light in the attached pictures, with three wires). Yet, I have a blue, black, and red. I figure someone may have rewired the boat at some point (there is a '05 date on the back of the halogen light)... my plan for next steps was going to be testing the various wires to determine which produce 12v and capping the 3rd - then making sure my navigation lights still work. Before I did that though I was hoping to sound out some of you all as maybe you recognize these strange three-wire lights. The rest of the boat was already retrofit with LED lights when I purchased, so not much help in examining those so far...

Thank you for any help or insight you might be able to offer - this forum has been a huge help for me. I'm really hoping there is not some obvious explanation for this that I am missing...

Dave
s/v Elro
1987 C34 #494

[KWKloeber]

Is it possible that the PO wired the switch to control another light down the line and the 3rd wire powers it (them?)?  Maybe the other V berth light?  Pull and check that one.

Defo an odd setup. I'd start by seeing what's hot, when - with a volt meter.

[mark_53]

Davee, I don't know if the wires are a problem if the lights work.  If so, you might just replace the incandescent bulb with a LED bulb.  Save yourself a lot of head banging.

[Stu Jackson]

Hi & Welcome.

Nice detailed [first] post, thanks.

It appears that the fixture may not be OEM, so who knows what a PO may have done?

Try using your DVM and finding out which one is hot, ground and maybe a switch leg.

Good luck and let us know what you find.

[Fred Koehlmann]

Nice post. Good question, and based on what I see I have some more. With the third wire, that appears to directly go to the switch, I'm wondering if this is a three-way switch? Does the switch on either light turn both lights on or off? Also since the black and blue are hard connected to the circuit board, I'm also wondering what's going on behind the wood panel? I'm guessing that these three wires are part of the fixture and not the boat wiring. Are you able to follow them in behind and see how they are connected to the main run? I'm wondering if the red and blue both connect to the boat's blue.

In any case, none of this should impact your switching to LED lighting, unless the sockets are not compatible. The only gotcha I found with LEDs is that with some of them you need to watch out for the polarity. If it doesn't work one way, switch them around.

[Ron Hill]

Dave : You can check with your VMeter, but the red should be + and the black -, the blue ??
I'd do as suggested. Take the base of the halogen bulb and match it to an LED bulb and try it that way.  If that doesn't work then start tearing things apart!!

A thought 

[Davee]

Hi All,

Thank you for all the helpful replies! I looked extensively for a switch but couldn't find anything like that so I ended up taking down the trim piece that was mounted below the light to take a look at the lights.

I found something of a nest of wires (pic 'nest' below) which I ultimately had to trace and try to draw (pic 'wires drawing' below) in order to figure out what I could do.

Essentially there were the black and blue wires run neatly up inside that I figure were the original ones from the manual diagram, those had blue plastic splitters (more on those in a sec) on them that split off blue and black lines that probably ran to the original light. Off those lines there was a strange wrapped split covered in electrical tape for one wire off each that ran forward (more on that in a sec). On the blue wire there was a twist on cap on the blue joining it to a small length of black wire that then joined to a blue and a red line with another twist on cap that ultimately went into the light. On the black wire it ended at a twist on cap that joined it to another black line that ultimately went into the light. I guess you're seeing why I had to draw it heh.

-----Re: the wires running forward - I disassembled a fair bit of the boat looking for where the lines running forward went... I couldn't find anything below the bunk in the forward cabin and the navigation lights still worked fine when I disconnected those two wires... the only thing I could find that might be where the wires went is a strange outlet/light socket(?) in the anchor locker (pic 'anchor locker dodad' below), I capped those wires, labeled them as best I could, and taped them together up inside.

-----Re: the blue plastic splitters - while researching before writing the original post I noticed a few people mentioning blue plastic clips/connections in conversations about the 12v system. I'm concerned that these are the blue connectors in question? If so I'll need to find a better solution and then go back in and remove them.

What I ended up doing was removing all the extra wires and just extending the blue and black (original) boat wires to the new LED light fixture I bought on amazon (pic 'new wire diag' below) using male and female quick disconnect heat shrink fittings. I didn't investigate retrofitting the old fixture with an LED bulb because I was a little put off by the weird three wire design and the new one has some features I like. The new LED light fixture has 20AWG wires coming off it, the boat wires are 12AWG I believe, and the wire I used in between is 16AWG.

The new light is in and works well (pic 'new light' below). The other side is much the same except there are no two wires going forward, I'm going to hold off doing that one until I learn a little more about the blue plastic splitters. 

Thanks again for the help, if you've noticed anything I could have done in a safer manner please let me know.