Marker lights on

[Deb & Chuck]

A friend contacted me when she arrived home last evening her Bigfoot 19 marker lights were on. The trailer is not hooked up to shore power or tow vehicle. Any ideas?

[Ron F]

I suspect that there is a short circuit between the 12V line and the tail light line. I've known that some people accomplish the same thing (for decoration) by placing a jumper wire between pin 3 and pin 4 on the 7-pin trailer connecter.

The problem could be a short within the connector or anywhere along the wiring run in the trailer.

[Jim Bennett]

Another thing that has happened to me, along the line of what Ron is saying, is that somehow the cable on the trailer to the plug got pinched, and shorted out the one brake/turn light wires. Something else to do a quick check on.

[Francesca Knowles]

In my experience, nearly ALL such weird electric anomalies on RV's are caused by bad/insufficient ground.

Case in point:

Something very similar to the O.P.'s problem here happened to me last year while drycamping alone out in the California boonies. The first night I was unhooked from the car and went to use the interior lights, they didn't come on- but the running lights did!! I wouldn't even have noticed except for the strange red glow outside....well visible since I had NO lights on the inside.

I started in all the wrong places, so it took me days to track the cause down. The culprit (only stumbled on by process of elimination) turned out to be insufficient ground at the taillights. I won't go into the l-o-o-o-n-g technical explanation of how that led to a "connection" between the interior light switch and the running lights and why the problem didn't occur when the trailer was hooked to the tow vehicle...

Point is, as soon as I installed a good heavy groundwire between the taillights and the trailer ground, the problem was solved.

And it only took me five (dark) days to figure it out!

[Thomas G.]

Originally Posted by Francesca Knowles

.......... The culprit (only stumbled on by process of elimination) turned out to be insufficient ground at the taillights................
Point is, as soon as I installed a good heavy groundwire between the taillights and the trailer ground, the problem was solved..................

Thanks for sharing this. I know that I've said this before repeatedly, but using the frame as a ground vs running a separate ground wire seems to be a constant source of problems.

[Francesca Knowles]

Originally Posted by Thomas G.

Thanks for sharing this. I know that I've said this before repeatedly, but using the frame as a ground vs running a separate ground wire seems to be a constant source of problems.

Just to clarify:

The as-built ground connection on my 1978 Trillium is on the trailer frame, under the wheel well by the converter.

In the case of my taillights, they'd been installed directly on the aluminum box that I carry on my trailer bumper, and at the time my ever-helpful husband believed that the box itself was sufficient ground for the lights.

It isn't, as he found out when I got home from that trip...

[Thomas G.]

Originally Posted by Francesca Knowles

............
It isn't, as he found out when I got home from that trip...

It starts out OK, but time and corrosion always seem to degrade the ground connections.

[Darwin Maring]

The only thing in common with the (interior and camper battery) and the running lights is the ground. There has to be a path between the positive and negative to have the running lights light up. How can this happen with the tow vehicle disconnected? There has to be a short between the Positive source of the battery and the Positive wire to the light.

Or, You just found a free source of power.

[Francesca Knowles]

Originally Posted by Thomas G.

It starts out OK, but time and corrosion always seem to degrade the ground connections.

If you're stressing the importance of maintaining/cleaning those connections, I certainly couldn't agree more! My own original ground is a case in point- the first time I cleaned it, it crumbled. Had to retap and go to a bigger screw etc...

Check those groundpoints, folks!

[Raz]

Originally Posted by Darwin Maring

The only thing in common with the (interior and camper battery) and the running lights is the ground. There has to be a path between the positive and negative to have the running lights light up. How can this happen with the tow vehicle disconnected? There has to be a short between the Positive source of the battery and the Positive wire to the light.

Or, You just found a free source of power.

Yup. While I certainly can understand how a bad ground can turn things off, I can't think of a way a bad ground could turn things on, at least not without some creative wiring having taken place. I would disconnect the battery and put an ohmmeter on the seven pin connector between the battery pin and the light pin and wiggle the wire. Raz

[Francesca Knowles]

Originally Posted by Darwin Maring

The only thing in common with the (interior and camper battery) and the running lights is the ground. There has to be a path between the positive and negative to have the running lights light up. How can this happen with the tow vehicle disconnected? There has to be a short between the Positive source of the battery and the Positive wire to the light.

Or, You just found a free source of power.

Confounding, isn't it? There's no doubt that the taillight ground was the problem- but why would that light up the running lights and interfere with the interior light???
I was so perplexed by that question that I posed a what-the-heck happened question elsewhere...and I got an answer, too, especially once I figured out that it's important to reveal that on my trailer, only the running lights are LCD's.

And I'd bet that any one of you guys with real electrical knowledge can explain why that matters-and what happened- much better than I can!



P.S.
It's understood, of course, that the trailer has its own on-board battery, right?

[Thomas G.]

Originally Posted by Francesca Knowles

If you're stressing the importance of maintaining/cleaning those connections, I certainly couldn't agree more! My own original ground is a case in point- the first time I cleaned it, it crumbled. Had to retap and go to a bigger screw etc...

Check those groundpoints, folks!

No, actually my viewpoint is that the 12 volt lighting system should have a separate, copper negative wire running from each electrical device, eventually connecting all the way to the plug at the tongue. Using the steel in the frame for a conductor is a false economy, as it is so fraught with corrosion issues and copper wire is so cheap.

Some people tilt at windmills, this is my mission.

[Francesca Knowles]

Originally Posted by Thomas G.

No, actually my viewpoint is that the 12 volt lighting system should have a separate, copper negative wire running from each electrical device, eventually connecting all the way to the plug at the tongue. Using the steel in the frame for a conductor is a false economy, as it is so fraught with corrosion issues and copper wire is so cheap.

Some people tilt at windmills, this is my mission.

Am I then to carry a six foot steel post to be driven into the ground whenever I wish to disconnect and use the tow vehicle???

[Raz]

Originally Posted by Francesca Knowles

Am I then to carry a six foot steel post to be driven into the ground whenever I wish to disconnect and use the tow vehicle???

There are two "types" of ground, chassis ground and earth ground. Earth ground becomes important in power and radio applications. Chassis ground is when you use the metal chassis as a wire. In a fiberglass trailer there's little value in using the chassis as a wire. A separate return wire is a much better solution. Raz

[Francesca Knowles]

Who said anything about using the chassis as a wire???

All my electricals- now including the taillights- are directly connected to the trailer ground by means of #10 white ground wire. (White is ground in Trilliums of that vintage).

Location of the single trailer ground is less important than that there be only the one connection. In my case, and as designed by the mfr., the trailer ground is located near the converter.

I guess I misunderstood Thomas to say that the ground is achieved by connection to the tow vehicle's ground...my mistake!

[Darwin Maring]

In Answer to P. Raz: There are two "types" of ground, chassis ground and earth ground.

Thanks for your post. I've decided to put a coffee can of dirt under the dinette seat near the converter for the earth ground.

[Raz]

Originally Posted by Darwin Maring

In Answer to P. Raz: There are two "types" of ground, chassis ground and earth ground.

Thanks for your post. I've decided to put a coffee can of dirt under the dinette seat near the converter for the earth ground.

Don't forget the 8 ft ground rod.

[Darwin Maring]

P. RazDon't forget the 8 ft ground rod.

I just coiled up 8 ft of copper wire in the can B 4 filling it with earth.
I'm wondering though if I should connect a wire to the frame.

[Darwin Maring]

I am thinking that because the light is a Light Emitting Diode (LED) and is getting it's power from one wire that is somehow a faulty ground that they got Cold Fusion up and running.

[Thomas G.]

Originally Posted by Francesca Knowles

.................In the case of my taillights, they'd been installed directly on the aluminum box that I carry on my trailer bumper, and at the time my ever-helpful husband believed that the box itself was sufficient ground for the lights..............

Originally Posted by Francesca Knowles

Who said anything about using the chassis as a wire???..........

I misunderstood you. I thought in the first post above you were saying that you were using the aluminum box mounted on the bumper as an electrical conductor. I would consider the aluminum box / bumper as an extension of the chassis.