Weird Electrical Gremlin: Suggestions???

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Rick D

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Jun 14, 2008
7,131
Hunter Legend 40.5 Shoreline Marina Long Beach CA
I really need some guidance here. I am chasing an electrical problem dealing with the bow running lights on my 1994 Hunter 40.5.
The problem manifested itself just before my race to Mexico which is where I am now. Altho the lights had worked fine the week before, they were not the night before, naturally. The lights are Hella series 40 which are dead simple. The stern light works fine. What puzzled me was that I read 12.8 volts to the light feed lines, but nothing when connected to the socket. Suspecting a bad connection where the electrical exits the bow pulpit, I redid all of those. So, I still have 12.8 volts but no lights.
I took the sockets apart and cleaned them up. I had a spare incandescent bulb, so I checked it directly to the starting battery and it worked fine. I installed it in the socket and tested it on the start battery and there was light.
So, now I’m thinking there is voltage but inadequate current to power the lights. I checked the connection at the panel, cleaned everything up and then checked it with my bow light in its socket. It worked normally. I then took a small halogen spare bulb and checked it on the bow light lighting and got nothing.
So, it is looking to me as if there is a bad connection or splice somewhere that is allowing just enough current for the volt meter but not enough to fire a bulb. What do you think? I figured I’d poll you here first before proceeding further.
BTW, the wires that exit the pulpit are not the same as those leading from the panel, so there must be a splice somewhere and I think they are all positive, so it must be picking up a ground somewhere too. To add to the issue, the wires run inside the pulpit to somewhere between the hull and anchor locker liner. Beats me where they exit. The wiring diagram is no help. It may be under a cover in my V-berth which is where you get access to the windlass (I hope). Any of you 40.5-ers know?
Suggestions welcome. I’ll check back in tonight.
 
Jul 25, 2007
320
-Irwin -Citation 40 Wilmington, NC
agreed it sounds like a bad connection. Just trace it back and you will find it
 
Feb 6, 1998
11,665
Canadian Sailcraft 36T Casco Bay, ME
You can very often have a connection that can pass voltage but not sufficient enough to pass any current. I see switches fail like this quite often. Check every connection back to the breaker and if all are good you may need to test the breaker... Often bow and stern lights are parallel wired so in that junction you may find the issue.
 
Oct 29, 2005
2,355
Hunter Marine 326 303 Singapore
Or it could be bad wires. Just last weekend, helped a friend troubleshoot low voltage at vhf radio. Measure 12.5V at radio, switched, voltage drop to 10.5V. Check and clean ALL terminations, no go. Decide to swap out a short length of bridging wiring, about 3ft. Presto! Problem solved. Apparently that wiring had gone bad inside it's insulation. Can't be seen until insulation is strip away.
 

RAD

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Jun 3, 2004
2,330
Catalina 30 Bay Shore, N.Y.
Try running a wire to the nearest ground (negative) and apply it to the socket and see if that works then you'll know if its a positive or a ground that's giving you trouble
 

Rick D

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Jun 14, 2008
7,131
Hunter Legend 40.5 Shoreline Marina Long Beach CA
Update

Well, it took all afternoon, but I removed the interior bow liner in the v-berth. Found the wire for the bow lights. Took a temporary ground wire from the windlass to the light. Vola... there was light. OK, so it's the ground. Re-did the splices. Still nada at the pulpit. Clipped back the wire. Oops, bad wire! Easy to pull another. Wait, not so fast. I can see where it enters the pulpit but can't make it budge. It enters on the aft of the pulpit through a small wire chase that enters the pulpit about three inches above the base, then runs either to the mid-rail or over the top to the forward portion of the pulpit. Swell, In a moment of desperation, I cut it back as far as I dared to expose good wire. Tested and it worked! I think the only way to run the wire otherwise would be to pull the pulpit, not something I care to do in Mexico. I have a plan to rig a 'temporary' bypass involving drilling a couple of holes if i have to, but I'm hoping I'll be OK. Have to put everything on hold for a day with weather coming in. Hope it will help the firefighters north of us. Thanks again for your help! Will advise.
 
Jan 27, 2008
3,045
ODay 35 Beaufort, NC
You can always get a bow light to clamp on the bow pulpit and run a cable to it above deck then to a cigarette lighter socket or some other power source. They even sell battery operated bow light with clamps for small power boats if you don't mind buying a lot of batteries for a while.
 

Rick D

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Jun 14, 2008
7,131
Hunter Legend 40.5 Shoreline Marina Long Beach CA
Update 2: Fixed!!! (kinda) and Lessons Learned

OK, so today when the rain cleared, I spliced together all the wires, found another incandescent running light bulb in the little ships' store here in the marina (!) and wired it all together and (halleluiah) the whole thing worked. There was just enough ground wire left before the pulpit to do one last desperation splice. It worked.

Not so fast. A few minutes later, the starboard side went off. I did an electrical check and found a one volt drop. Still should have fired the bulb. It couldn't be the OTHER ground running to starboard, could it? I ran a test ground, and yup, it was it. Cut it back an inch and nothing. Checked the other end. Same issue. Ran a bypass outside of the pulpit and spliced it in. Let there be light. There was.

OK, so there is the learning experience here about checking connections and not trusting simple voltage tests (at least be suspicious). And, why oh why was it the ground wire that had failed on two different runs? Oh, and the wire inside the boat is good marine grade tinned wire. Naturally, the stuff in the pulpit IS NOT. I need to pick brains about the bow pulpit, but I will start another thread for it. I think I've bored everyone with this one.

 

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