Voltage to exterior porch lights

oldstick · 10-08-2016, 08:42 PM

Trying to trouble shoot a problem with my two porch lights on the curb side. Neither are working, both on the front shell. The street side light, also on front shell works. Also all the other 12V interior lights plus the 12V exhaust fan work as well.

So I haven't done a thorough check with a volt-meter yet, but I did checkout the switch near the door and it reads OK. But voltage across the two leads on the switch was low, 3 volts or so. I know this could possibly be a skin grounding problem on both outside lights and I will check this out. But in the meantime, my specific question is where is the next upstream 12V junction to these lights?

The TM wiring diagram I have is a little vague but the only logical place I can see for any junctions feeding to the interior lights, fan and exterior lights must be located under the air conditioner trim panel. Is this correct before I start taking things apart? The same diagram I have only shows one 12 gauge 12V junction to the front shell located in the fridge vent area. I assume there is no problem there, since everything else is working.

Padgett · 10-09-2016, 07:53 AM

You did not mention if you swapped bulbs or cleaned the sockets. Sometimes my door light needs some jiggling.

**Bill** · 10-09-2016, 07:57 AM

The problem is often corrosion in the socket or on the base of the bulb. In case you haven't already done it, remove the bulbs and use a bit of fine sandpaper to clean the bulb's metal tip and brass sleeve. Then clean the inside of the socket, using a pencil to push the sandpaper around a bit. Good luck.

The voltage across the two leads of the switch was 3 volts? I don't know how this could be. If the switch is ON, there should be zero volts across the leads, and anything else indicates a bad switch. If the switch is OFF, no current is passing, so a skin grounding problem won't cause any voltage drop. In other words, there should be full battery voltage across these two leads. Was the switch on or off when you checked it?

Bill

oldstick · 10-09-2016, 12:15 PM

Thanks everyone, I think I found it. The bulbs are the 912 blade type and they are good and the sockets clean.

The long version: I removed the switch by the door and it checked out fine with the ohm-meter. But I was getting an inconsistent voltage reading from the hot wire to the switch when connected to a good ground. I was using the 1157 light socket above the stove for the ground. I would sometimes get 10 to 11+ volts but never a steady reading and never 12 or more. Next time it would read 2 or 3 volts then sometimes 5 or 6 always fluctuating.

When I put a jumper between the switch wires, similar puzzling readings at the light sockets. Took off one light assembly and looked at the ground connection, but it seemed OK. That is when the bell rang that I remembered the ceiling exhaust fan had also acted flaky a while back, refusing to come on then it started working later. I assumed the fan motor at the time.

So guessing from the wiring diagram, I pulled off the plastic trim panel to the AC unit. There were a couple black 12V wire junctions using the 3-way crimp splices which I have always had problems with. I monkeyed around with those, in particular the one leading off in the direction of the fan and the porch lights. In the process of testing with one of those sharp pointed automotive wire probes, I accidentally contacted the metal ceiling and blew the fuse to the front shell ceiling. Ran to the store for some spare fuses, put a new one in and suddenly I'm getting good voltage at the lights and they are working. So am assuming it was the wire splice and while I have the panel off, will replace that with wire nuts.

SMCrane1554 · 10-21-2016, 08:49 PM

I have a similar problem. The front and curbside patio lights on my TM 3326 aren't working. The street-side patio lights, which appear to be on the same circuit, are working. I checked power across the terminals of the non-working lights, and no power at all. I re-did all four of the connections inside the roof AC shroud with wire nuts, and the same lights still don't work. I replaced the bulb in each light with a bulb known to be good. Still no light. Any suggestions?

oldstick · 10-22-2016, 09:13 AM

I didn't actually redo the wire splice this time, I decided to just give it a good squeeze with pliers, tape it up tight and call it OK for now. I'll know where to look if it happens again.

Anyway, on my 3023 there are two porch lights on the door side of the camper, one near the front corner and one beside the door. Both of those appear to be on the same circuit. This wire branched off from the main black wire underneath the inside AC trim shroud with a single switch located above the door on the inside. That splice is where I assume I had a problem. But I really can't say for certain because all I did was jiggle around with the splice and tape it up.

Also there is another porch light on the opposite side of the camper. It has it's own switch built into the light assembly. I had to remove the assembly and clean up the bare ground wire connection on that light and now it works fine. The best I could tell, the 12V feed to that light braches off from the main black wires somewhere near where the light is located.

You can see the wire bundles coming underneath from the breaker panel going up to the roof areas and other devices, if you look in the outside access panel to the fridge compartment. The bundles appear to feed up attached to one of the lift arms.

So if you are not getting power at the lights, check the switch(s) first. They seem kind of cheap and suspect in my opinion. Then, if needed, trace wires back to the one junction inside the AC for the door side lights. Then try to find the junction for the back side light, if necessary. Eventually tracing back down to the black wire junctions behind the fridge and back to the fuse panel all as necessary.

Also, I assume all the interior lights and other 12V stuff do have power? If not that could give you more clues as which way to look.

And dohhhh! I almost forgot, even though I hinted at it above. When checking for voltage at the light sockets, don't trust the ground side of the socket to be good. Try and reach a known good ground like a working light socket inside or something. If you take out the 4 screws and pull out the light assembly you will see there is only a single ground screw into the metal exterior skin. Easy to get weathering and corrosion in this location. Like I mentioned I had to clean and apply some bulb grease to the one ground screw hole in order to get that light working consistently. That was the light on the back side.

SMCrane1554 · 10-24-2016, 07:05 PM

I checked the patio light fixtures on the front and curbside, and I could not find a ground screw. I know that I have power to those lights because I can ground the voltage checker on one of the screws which attach the fixture to the outer shell and contact the power lead with the voltage checker, and the voltage checker lights up. There is a ground in the small oval junction box on one of the supports for the front shell, which I pulled loose and re-attached. There are ground connections in two junction boxes under the TM, and I re-did both of them. I checked the curbside patio light again, and the voltage checker will not light when I touch the white and black leads attached to the switch. Any advice would be helpful.

oldstick · 10-24-2016, 08:31 PM

Quote:

Originally Posted by SMCrane1554

I checked the patio light fixtures on the front and curbside, and I could not find a ground screw. I know that I have power to those lights because I can ground the voltage checker on one of the screws which attach the fixture to the outer shell and contact the power lead with the voltage checker, and the voltage checker lights up. There is a ground in the small oval junction box on one of the supports for the front shell, which I pulled loose and re-attached. There are ground connections in two junction boxes under the TM, and I re-did both of them. I checked the curbside patio light again, and the voltage checker will not light when I touch the white and black leads attached to the switch. Any advice would be helpful.

I understand exactly what you did and might be able to help in that case.

The 4 screws that attach each light to the shell also go through the metal skin and indeed are probably a very good ground point to check against if you scratch off the white paint from the screw heads. Also the oval junction box on the back side is the 120 Volt wiring junction. The metal housing and screws of that box are also a very good ground point, in fact I used the same junction box to determine that my back side porch light had a bad ground connection.

So if you are reading 12V to these good ground points, but NOT 12V between the two socket leads, then you most likely have a problem at the light socket's ground lead.

The ground wire lead on each light socket doesn't use any of those 4 mounting screws.

To find the light socket ground, remove all 4 of the mounting screws, then gently pry around the perimeter of the light socket. There may be calking that you have to scrape and remove. Behind the light assembly is a thin metal plate that must be gently pried off as well. Behind the metal plate, you should see the ground wire from the bulb socket that is attached to the skin with another small screw. That is probably where the bad ground connection to the light needs to be cleaned up.

SMCrane1554 · 10-24-2016, 09:36 PM

oldstick,

Neither the front nor curbside patio lights on my 2008 3326 have a ground screw. The white wires are spliced with the splices that cut through the insulation of the wires, but no ground screws. There are no junction boxes behind the lights, either. Just a small cavity in the foam between the inner and outer skins. I have checked and re-done every ground connection that I have found so far with no success. I have pulled on the white wire splices, but none have come apart. I found an exterior junction box underneath the TM that has at least 10 splices, mostly butt crimps with light-gauge wires, and the whole mess is in an interior 1-gang old work box with a metal cover from an exterior junction box. I will have to replace that with a proper exterior flush-mount junction box. I'll keep looking. Thanks for your suggestions.

oldstick · 10-25-2016, 08:39 AM

Wow, I see now. Do you happen to have the owners manual that came with the TM? Mine had a wiring diagram and for the exterior lights, it states "grounded to exterior skin". If your's has the same, then possibly someone else has modified the wiring.

Sounds like you are going to have to trace through all those splices and the junction box, etc. Good Luck. If you run into more problems, there are plenty of experts on here.

Check for continuity between the good ground points you found and the ground wiring of the lights, starting at the ground terminal of the socket. One trick I've used is to pierce the insulation (carefully, watch fingers) with a small straight pin, to check continuity at various points, before and after each splice, etc. to isolate where the bad connection is.

I've used those types of splices before, the ones you crimp through the insulation, and have always had trouble with them working loose or oxidation inside, etc.