RVing Drives Me Nuts ---- Electrical Issue

Hoppypoppy wrote:
...Again pardon my dumbness....when you say a "single bulb system" are you saying one of the three bulbs could be out, and that is taking down the whole trio of lights?

Are you saying you actually know there are three bulbs in the suspect light? I looked at a trailer similar to yours online and it looked like a single bulb design. I could be mistaken.

In either case the problem is still similar to my earlier statement. If there are indeed three separate bulbs that sorta rules out the sockets and bulbs themselves and would indicate a problem with the ground wire for those bulbs as it is unlikely all bulbs and/or all sockets are bad.

Actually I would be surprised if you do have three separate bulbs but confirm and let us know.

Hoppypoppy wrote:

handye9 wrote:
What is your tow vehicle?

Some trucks have seperate fuses/relays for left and right stop/turn signal lights. Certain years of F250's are wired like that.

Check your owners manual. Maybe your problem is in the truck.

It's a 2003 GMC 2500HD. All the truck lights are good.

The fuses I'm talking about, have nothing to do with truck lights. They only control trailering lights.

Mine are in a fuse/relay box under the hood.

Look at this . It's a GM truck type forum. A fellow is describing a problem just like yours. The recommended fix was a fuse/relay in a box under the hood.

Look here, 03 GMC Sierra, on page 5-111. It shows seperate fuses for left and right stop/turn trailer lights. The fuse box is on the end of the instrument panel (driver side).

handye9 wrote:
What is your tow vehicle?

Some trucks have seperate fuses/relays for left and right stop/turn signal lights. Certain years of F250's are wired like that.

Check your owners manual. Maybe your problem is in the truck.

It's a 2003 GMC 2500HD. All the truck lights are good.

What is your tow vehicle?

Some trucks have seperate fuses/relays for left and right stop/turn signal lights. They also have a seperate fuse/relay for trailer running lights. It's possible to have tail/running light and no turn/brake light, on one side or the other. It's possible to have turn/brake lights and no tail/running light. Certain years of F250's are wired like that.

Check your owners manual. Maybe your problem is in the fuse box of the truck.

Generally the ground wire in the plug goes to the frame.. Then ground leads on the assorted other things also go to the frame.. It is possible for the light socket to have a bad ground.

That said, Some folks the ground lead runs all the way to the lights.. On my car, when I'm towing, the tow lights are 100% independent from the rest of the ride. They only ground via the motor home.. and a dang poor job of it they did too (till I fixed it).

jmckelvy wrote:

Hoppypoppy wrote:
Please forgive my ignorance, but I am an electrical illiterate. I went back to the 5er and tried all the suggestions I had received at that point. More came in later, and I hope to go back again today. (little under the weather) My latest question.....is it possible, the ground wire in the power cord is itself grounded to the pin box itself? This may be the ultimate in stupid questions, but I want to eliminate all possibilities before I tear into the light fixture itself. One of the problems I am having in locating a ground wire is, the trlr is an All Season so no access from underneath. Thanks again for your help and patience.

The three posts prior to yours are the most accurate. This problem is not related to your 7-pin connector given the symptoms you report. It appears you have a single bulb system. The only things common to the tail, brake and turn lights are the bulb itself, the socket with the ground (common) connection and the ground wire to wherever it connects to the ground for the rest of the lights that do work.

Start by removing the bulb and ensure a good clean connection to the socket. Make sure you have a good bulb. Let us know what you find.

Again pardon my dumbness....when you say a "single bulb system" are you saying one of the three bulbs could be out, and that is taking down the whole trio of lights?

Hoppypoppy wrote:
My latest question.....is it possible, the ground wire in the power cord is itself grounded to the pin box itself?

Yes that is possible. Easy to check continuity from the 7-pin ground terminal to frame. Does not matter where it connects just so that it does.

Hoppypoppy wrote:
Please forgive my ignorance, but I am an electrical illiterate. I went back to the 5er and tried all the suggestions I had received at that point. More came in later, and I hope to go back again today. (little under the weather) My latest question.....is it possible, the ground wire in the power cord is itself grounded to the pin box itself? This may be the ultimate in stupid questions, but I want to eliminate all possibilities before I tear into the light fixture itself. One of the problems I am having in locating a ground wire is, the trlr is an All Season so no access from underneath. Thanks again for your help and patience.

The three posts prior to yours are the most accurate. This problem is not related to your 7-pin connector given the symptoms you report. It appears you have a single bulb system. The only things common to the tail, brake and turn lights are the bulb itself, the socket with the ground (common) connection and the ground wire to wherever it connects to the ground for the rest of the lights that do work.

Start by removing the bulb and ensure a good clean connection to the socket. Make sure you have a good bulb. Let us know what you find.

Please forgive my ignorance, but I am an electrical illiterate. I went back to the 5er and tried all the suggestions I had received at that point. More came in later, and I hope to go back again today. (little under the weather) My latest question.....is it possible, the ground wire in the power cord is itself grounded to the pin box itself? This may be the ultimate in stupid questions, but I want to eliminate all possibilities before I tear into the light fixture itself. One of the problems I am having in locating a ground wire is, the trlr is an All Season so no access from underneath. Thanks again for your help and patience.

Hoppypoppy wrote:
Brought my 2002 Cardinal home from storage last Fri. Checked lights - everything fine. 5er sat in front of my home til this morning. (Tues) Hooked it up, ready to go, no tail, brake or turn signal lights on right side only. Left side fine. First thought was a ground issue. Now the dumb question.....is the only ground on these rigs the ground included in the power plug to tow vehicle? Any other suggestions? Thanks all.

The 7 pin does not have a "right side" pin and a "left side" pin. Neither does it have a "right side" ground or a "left side" ground. If the problem was in the 7 pin, it would not just affect one side.

While the brake light and turn signal are one circuit, the tail light is a separate circuit/filament. If it was a hot wire, only the tail light, or, only the brake light/turn signal would not be working. It is unlikely that both the hot wires would fail at exactly the same time. (Unless a critter got in there and chewed them.)

The evidence (2 separate circuits, with one of them only affected on one side) points to a bad ground on the light fixture. Try running a temporary separate ground wire from the light fixture to a known good ground. I'll bet that solves the problem. If so, you can attach a permanent ground wire from the light fixture to ground.

If the ground between the 5er and the tow vehicle was the problem, it would not be only that one light fixture.