grounding issue

[johninhamilton]

I have been having DC electrical problems with my 89 fifth wheel and have discovered that the dc panel is not grounding.It has a solid copper rod form the groeunding log run to the frame in the front storage area.I ground off the paint and i am on bare metal but it still wont ground.I next trie taking a test light and hooking it to my truck battery and find some where on the camper where it would ground,and nowhere that i touch will ground it?Tried the coupler for the hitch,the frame all over inside the front storage are,these are big pieces of metal ,why wont it ground?Thanks for any help.

[Jagiven]

Grounds can be a major pain to find the issue. One of the things I like to use is a star washer on both sides of the lug. They really bit into lug, the bolt head, and the steel frame, making a good solid connection. You could have corrosion inside the lug, which could be hard to find. For that I like to use “Rail Zip”. Rail Zip is made for model railroading; however, many old car enthusiasts use it on Lucas wire connectors as they have a bad tendency to corrode. It seems to take about 24 hours for it to do its magic. Otherwise you really need to get the multi-meter out and start checking for continuity.

[johninhamilton]

how do i use the multimeter to find the problem?thank you for replying.

[David472]

You can use the multimeter in much the same way as your battery and light bulb set-up. The multimeter (set to measure resistance) has a 1.5 volt internal battery and a meter indicator instead of a light bulb. The meter indicator will give you a reading of how many ohms of resistance there is between the probes.

[tnchuck100]

From your description it does not sound like you have a grounding issue. Since you are not familiar with how to use a multimeter I would highly recommend you find a friend who understands electrical stuff. When you deal with wiring it is very easy to compound a problem.

[RoyBraddy]

I'm not able to determine where you are talking about on not having a frame ground. What is not working...

This is a diagram of my Power Distribution Center which should be typical to yours.


As you can see i have a few actual connections going from a component to the trailer frame ground which is a solid copper wire except at the battery terminal which are all 4AWG cables going to an individual frame ground lug. None of my battery negative terminal cables are wired to the same frame ground terminal lug.

In my wiring concept the 12VDC side of the Power Distribution Panel shows the 12VDC wiring that goes to components, appliances, or lighting items all use two conductor WHITE and BLACK boat wiring... All of these 12VDC items have both a Positive and Negative wiring cable going to them. None of them uses the frame ground for connectivity. They all have two conductors feeding them that comes from the 12VDC Fuse panel.


This is the way most thing are wired today. Years ago alot of 12VDC component only used a single "hot" wire and the ground was picked up by connecting to the closest chassis frame. This practice is wide open for bad connections so not used much anymore for connecting up the 12VDC appliances etc...

The only units in my trailer setup that uses a single heavy copper ground wire is the Converter/Charger unit, The Inverter Units, and the Power Distribution Panel unit. I also have a frame ground cable going to one side the Electric Brakes and one of the pins coming from the Tow Vehicle 7-way cable. Everything else that is 12VDC is fed by two conductor (White and Black) Cables coming from the Power Distribution Center. Even my trailer lights all use two conductor cables to each trailer light to prevent bad connections.

Also please note the 120VAC Wiring only has the GREEN WIRE going to frame ground. Both the "HOT" wire and the "NEUTRAL" wire are routed back to the SHORE POWER PEDESTAL and are above GROUND potential. The SHORE POWER CABLE WHITE NEUTRAL WIRE pick up its grounding at the SHORE POWER Source. It must be floating at the trailer side (NOT CONNECTED TO FRAME GROUND). For wiring to 120VAC appliances the BLACK WIRE and the WHITE WIRE are floating and connected only to the SHORE POWER connection. the GREEN WIRE however is wired to the trailer FRAME GROUND as shown in the diagram above.

Just passing on info here (Food for thought)... *may not be like your setup at all...

This pretty much describes my 2008 Starcraft 14RT POPUP trailer 12VDC wiring...

Roy Ken