Help with stern light problem

[greenbm]

This is my first time posting a question but I have been reading the boards a lot and have been help a lot by reading other peoples' posts. My stern light has not worked since I bought the boat last summer. I tried the obvious simple solution first and changed the bulb. No luck. So Tonight I tried to diagnose the problem and what I've found has left me confused. Here is what I did/found:

1. Put multimeter to the contacts in the bulb socket and got a 12V reading. BUT I noticed this was when my switch was in the off position. At least I think it's off. It's a rocker switch labled Nav/ANC and the middle position seems like it means off since neither of the lights on the switch come on when in this position. Am I correct in thinking this?

2 with the switch in bothe of the "on" positions I got no reading on the multimeter

3 when I put the test light on the negative battery terminal and touch EITHER of the contacts in the light post socket the test light cm on. When I reverse and clip the test light to positive it won't come on regardless of which contact I touch

I'm wondering if the problem is in the switch or maybe how the stern light is wired to the switch. I may be leaving out important information so if I am, please ask and I will try to answer. Thanks in advance for your help. Like I said, I've learned. Lot from you guys already.

 

[bruceb58]

Re: Help with stern light problem

The light is missing its ground or it has a highly resistive path to ground.

You can do a test with a test lead by connecting it to the negative side of the battery and the ground side of the light. Hopefully it has color coded wires going to it.

I also wouldn't be surprised if your stern light might illuminate slightly when you connect the test light between the negative terminal of the battery and the ground side of the light. it will be faint depending on how much current flows through your test light.

Welcome aboard!

 

[greenbm]

Re: Help with stern light problem

I know very little about electricity so can you explain to me why the test light would come on when i touch either one of the contacts in the light pole socket? I would have expected it to come on only when I touched the positive contact (when the test light is hooked to negative battery terminal)

Also Why would i be getting a volt reading with the switch off but not when it's on? Thanks again for the quick reply

 

[sam am I]

Re: Help with stern light problem

Very wise questions, you know more then you lead on, indeed.......

Assuming that the pole itself is isolated(typically) then the contacts are the positive and negative.......Just establishing basic ground work, nobody panic.

With the test light (assuming incandescent type, essentially a low resistance stand-in light your using in place of the actual light, perhaps a watt or two) clip connected to ground and test probing both the contacts with the switch OFF...........No, you should NOT be able to get the test lamp to light on either contact. You claim the lamp lights on both contacts in this case?

And yes, normally, with switch on and test lamp clipped to ground, one contact and only one contact (the 12V) should light the lamp.

Any yes, when probing the ground contact with the test lights clip to the positive side of the batt, the lamp should only light when touching the ground contact (switch on or off)

Anyway,

Two causes come to mind.....

1) The ground wire circuit to the ground contact pin is open (perhaps burn't open due to shorting to the 12V wire pair) and the pin (or wire near) is shorted to the positive pin (or wire near)

2) The positive pin wire is not shutting off with the switch due to a short to 12 volts somewhere going back to the switch and/or in the switch itself (switch contacts overheated and fused together due to when #1 occurred and protection fuse Amp rating (or tin foil) was too high allowing China Syndrome ).

Basically(dramotional unabridged version), at the time of the murder, errrr incidence, the 12V came in contact with the ground violently, probably in or close too the light base, your ground path fried open and in half, the ground (battery negative) side fell away suddenly and is laying abandoned somewhere, the contact's negative side stayed fried/fused to the positive side where the two initially touched burning the negative side in half and the switchs' internal contacts fused closed at the same time rendering it unconscious and unable to function ummmm, unfunction. Wheeeew, or not.

You have access to the switch itself? Pull the wires (Spade lugs I hope) off and re-test, let us know. Inquiring minds need to know

 

[greenbm]

Re: Help with stern light problem

You have access to the switch itself? Pull the wires (Spade lugs I hope) off and re-test, let us know. Inquiring minds need to know

I can easily (famous last words) get to the switch and will disconnect and report back what I find. What exactly should I be looking/testing for? If I don't hear back from you in time, I will just poke around with multimeter and test light on various places (leads that are no longer on the switch, etc.) My boat is stored in my freind's garage so it might be a couple days before I get back to it. I will take some pictures too that might help.


"No, you should NOT be able to get the test lamp to light or either contact. You claim the lamp lights on both contacts in this case?"

The test light definitely came on when I touched both each one of the contacts. I'm 95% sure the switch was off when this happened. I willdouble check. That would be inline with the fact that I was reading 12V on the multimeter at the light bulb socket when the switch was off, right?

 

[sam am I]

Re: Help with stern light problem

Yeah, just pull ALL the wires off(tag/lable them if you need too) the switch and go back with test lamp and

1) Connect the test lamp clip to ground, probe both contacts, note results.

2) Connect test lamp clip to battery positive, probe both contacts, note results

Oh and if you have an DVM, sure, with wires to switch still dis-connected AND NO voltage present from test #1 and on low ohms scale(if not auto ranging), measure across the two contacts, note results.

Yes, your inclination is correct. The beauty of test lamps(incandescent types) in this case, is it's inherent low resistance. This inheritance tells us that both positive and negative paths are both connected well enough(low resistance) to 12V and are capable of carrying enough current to light the lamp. The normal 12V path should be thou, eh? We want that but, not the ground. Hence, that ground contact is somehow shorting (or close too) to 12V.

If that ground contact was connecting to 12V say equal to the resistance of the test lamp, the lamp would light but only half lite. Then if you knew the resistance of the test lamp(I guessed a 1 or 2 watts @ 12V, you could say the short to 12V is equal to that. So 1.5Watts @ 12V = 96Ω for example V^2/P=R. Your DVM will make short work out of this measurment though.

 

[Splat]

Re: Help with stern light problem

Lets slow down here. The test light lighting of either contact is the hint.

Would bet you a case of beer this is a simple grounding problem. The light is coming on because of a ground loop. It's using the test probe to complete the circuit. The energy flowing through the resistive bulb is causing it to heat and illuminate. It may not necessarily be the the stern light circuit causing the hunting for ground.

The first thing I would do, before yanking terminals off the switch is clean all my grounds. The one on the battery, as well as the one going to the engine block. I would pay special attention to where ever the stern light grounds. Check the splices wherever the stern light is connected into the wiring harness that runs up to the switch. Make sure they are clean and corrosion free.

It possible that this is a short causing this, but a floating or highly resistive ground is a much more likely culprit.

Welcome to the forums by the way.

Bill

 

[sam am I]

Re: Help with stern light problem

Like I said, I could be wrong, been there done that and drank to that. Bruce mentioned grounding the ground side of the light, that would do it.

 

[bruceb58]

Re: Help with stern light problem

I know very little about electricity so can you explain to me why the test light would come on when i touch either one of the contacts in the light pole socket?

The bulb's filament is conducting when you are on the ground side. That is why I suspect the ground is gone.

Also Why would i be getting a volt reading with the switch off but not when it's on?

That one is a little puzzling. Is your switch an illuminating switch?

 

[sam am I]

Re: Help with stern light problem

Splat may have hit it.........But, the test lamp should be dimmer though (hard to tell sometimes for people to report) The ground contact at the socket maybe floating (being pulled up to 12V through another device/lamp wired to 12V before the switch sharing the same(ungrounded) ground.....not sure how this thing is wired, hard to arm chair these things sometime. Ground the ground side will do one of two things, fix it(tell us) or smoke something. I figured removing a few spade lugs hasn't killed anyone yet

 

[greenbm]

Re: Help with stern light problem

That one is a little puzzling. Is your switch an illuminating switch?

Yes the switch is an illuminating switch. Just to double check, I will take a voltmeter reading with the switch in all 3 positions and report back. I know I got a reading when in the off position, but I'm second guessign whether I tried both of the On (NAV/ANC) position or just one.


I will try what Splat mentioned by tracing all thr grounds and making sure I have good clean contact.

One other hting that I found odd was that the two wires going into the light pole socket were soldered to very short (1/2 inch??) leads coming out of the socket. the replacment socket i found online had longer (7 inch) leads coming off. The problem with the soldering being to such short leads is that the exposed wire (soldering) is so close to one another. As i'm typing this, Im envisioning someone else reading this and saying "well of course thats a problem you dumb *****).

I will take a picture of this to show you what I mean.

 

[sam am I]

Re: Help with stern light problem

Dude!!! It just might be shorting there :facepalm: , like my story better, had more drama.

Should take out fuses though...Hmmmmm

At any rate, heat shrink those up nice and tight, re-check with test lamp connected to ground.

1) lamp off probing ground contact....problem found, insert bulb, test switch.

2) lamp on [look for open ground(either caused by that shorting out at socket and/or open by loose connections)]

Perhaps needed.....Think this is about right?, Glad it's a sloooooow day in the hood. And we get paid for this right?

or most likely one lamp, same difference though

Not sure how OP is getting 12V on "A" or "C" with switch off and grounded test lamp unless switch stuck on or shorted between A and B or C and D.......In this drawing anyway hmmm, could be drawn wrong though. I assume the ANC light comes on with NAV light, mine does anyway, but not the reverse. Thinking we need a uPc and a leaky diode :laugh:

"B" and "D" lighting up a grounded probe is through R_Load though

 

[Splat]

Re: Help with stern light problem

Splat may have hit it.........But, the test lamp should be dimmer though (hard to tell sometimes for people to report) The ground contact at the socket maybe floating (being pulled up to 12V through another device/lamp wired to 12V before the switch sharing the same(ungrounded) ground.....not sure how this thing is wired, hard to arm chair these things sometime. Ground the ground side will do one of two things, fix it(tell us) or smoke something. I figured removing a few spade lugs hasn't killed anyone yet

Agreed with pulling a few lugs off Lol. I just suspect this is a floating ground issue. Maybe a very simple fix without having to tear into something needlessly.

Your advice is sound, and I didn't mean to knock it, if it came across that way. I just hate creating work for myself or others. Years of chasing this stuff has taught me to always look for the simple stupid obvious stuff first, as usually it's the culprit.

It's like chasing a lighting problem on a trailer. You can get all kinds of weird volt readings that don't make any sense. Voltage where there shouldn't be any, lights blinking when they shouldn't, or opposite of others. Before you know it you're tapping into the vehicle wiring harness, and changing converters, convinced it's a leaking diode, when all it was, was a corroded ground screw.

One way or another we'll get the op fixed up. May take some bouncing off ideas off of each other, but we'll get there.

 

[sam am I]

Re: Help with stern light problem

Agreed, Don't like going to the dam first to check turbines for a bad light bulb in the kitchen..... Got one for ya too, Cruse control on Honda would shut off/kick out when I turned my headlights on ........Turns out one of the quad set of brake/tail bulbs, one filament failed in such a way that the brake filament broke apart and laid across the tail light filament(or vise versa, was back in the day) . Turning on the headlight sent 12V backwards through the brake light circuit into the cruse controller, it thought the brake peddle was being stepped on...... :crazy:

Ended up pulling spade lug wires off the brake peddle switch to take the braking shut off out of the loop to realize the problem was the braking circuit causing it .......if I had only thought to check the tail lights first......... :faint2:

 

[greenbm]

Re: Help with stern light problem

Decided to just rewire the light base completely and everything now works fine. First time I really paid attention to all the wires behind these itch panel... Man there's a lot going on back there. Luckily I was able to determine pretty easily which of the wires was going to the nab light and by process of elimination figured out which wire was for the anchor light. Plug it in and we are in business. Glad I didn't have to spend money on a new lamp or base

 

[sam am I]

Re: Help with stern light problem

Good deal.......and safe boating.

 

[greenbm]

Re: Help with stern light problem

Thanks. And thanks for the help

 

[sam am I]

Re: Help with stern light problem

You're welcome and thank you for following up with final outcomes.

 

[bruceb58]

Re: Help with stern light problem

So I am curious what your issue was. Was it a bad ground form the lamp base?

 

[greenbm]

Re: Help with stern light problem

So I am curious what your issue was. Was it a bad ground form the lamp base?

I'm not sure. I wanted to wire the lamp base directly to the battery to check whether or not the base or light itself were working. once I confirmed that they were and I already had everything ripped apart, I decided to just rewire all the way to the switch.