Trailer side lights not working ?

[Slickcraft]

I agree with 8gv, first check the ground connections.

Alan

[Descant]

Originally Posted by Slickcraft

I agree with 8gv, first check the ground connections.

Alan

The ground goes through the hitch to the truck. If the trailer is not connected well to the truck hitch, you won't have a good ground. Some people grease or lubricate the hitch/ball to reduce squealing. OOPS.

[8gv]

I have not seen a trailer wiring set up that relies on the trailer ball to provide continuity for the ground.

In my experience there is a white wire on the trailer side of the connector that gets attached to the trailer frame.

The wiring connector on the vehicle side has a wire that goes to the vehicle ground.

When the two connectors are joined the ground has continuity.

[bigdog]

Originally Posted by 8gv

I have not seen a trailer wiring set up that relies on the trailer ball to provide continuity for the ground.

In my experience there is a white wire on the trailer side of the connector that gets attached to the trailer frame.

The wiring connector on the vehicle side has a wire that goes to the vehicle ground.

When the two connectors are joined the ground has continuity.

I think I may have stated my problem a little hastily, and somewhat (VERY) embarrassed When I tested the lights in the beginning, I just connected the wiring harness from trailer to the truck, I never had the trailer hitch connected to the truck hitch ball as if I was towing.

In your Post you stated 'I have seen wiring set up that relies on the trailer ball to provide continuity for the ground', this may be the reason?
Going to actually attach trailer to truck hitch/ball and see if it resolves my issue. If it does, I feel like such a dumby !

Will report back with results....
.

[jeffk]

Originally Posted by bigdog

I think I may have stated my problem a little hastily, and somewhat (VERY) embarrassed When I tested the lights in the beginning, I just connected the wiring harness from trailer to the truck, I never had the trailer hitch connected to the truck hitch ball as if I was towing.

In your Post you stated 'I have seen wiring set up that relies on the trailer ball to provide continuity for the ground', this may be the reason?
Going to actually attach trailer to truck hitch/ball and see if it resolves my issue. If it does, I feel like such a dumby !

Will report back with results....
.

REREAD 8gv's quote. "I have NOT seen seen a trailer wiring set up that relies on the trailer ball to provide continuity for the ground."

The continuity does NOT rely on the hitch connection. The WHITE wire is grounded to the trailer frame on the trailer side and to the truck frame on the truck side. When you connect the two connectors (truck WHITE TO trailer WHITE) it creates continuity between the two frames.

In fact, if hooking up the trailer "fixes" the lights, it simply exposes the real problem, that one of the WHITE grounds are no longer properly connected at the frame (corrosion/wear/broken wire).

HOWEVER, the ground is NOT your problem. If you have a bad ground, NONE of the lights will work. You have some lights working therefore the ground is working. (Unless the lights are working but dim. That would indicate that the current is grounding through a secondary (poor) path)

I suspect you may have a couple problems. One, a broken connection to your TAIL LIGHTS which also supply the side markers and license plate light. If the back tail lights are working, it is the specific feed wire to the side markers and license light OR corrosion/wear at some point in the loop that is blocking the current.

Two, the flickering could be loose connections at various places along the way, including the ground wire. The first place to check would be the actual car to trailer connecters. Are they clean and fitting well/snugly?

[bigdog]

Originally Posted by jeffk

REREAD 8gv's quote. "I have NOT seen seen a trailer wiring set up that relies on the trailer ball to provide continuity for the ground."

The continuity does NOT rely on the hitch connection. The WHITE wire is grounded to the trailer frame on the trailer side and to the truck frame on the truck side. When you connect the two connectors (truck WHITE TO trailer WHITE) it creates continuity between the two frames.

In fact, if hooking up the trailer "fixes" the lights, it simply exposes the real problem, that one of the WHITE grounds are no longer properly connected at the frame (corrosion/wear/broken wire).

HOWEVER, the ground is NOT your problem. If you have a bad ground, NONE of the lights will work. You have some lights working therefore the ground is working. (Unless the lights are working but dim. That would indicate that the current is grounding through a secondary (poor) path)

I suspect you may have a couple problems. One, a broken connection to your TAIL LIGHTS which also supply the side markers and license plate light. If the back tail lights are working, it is the specific feed wire to the side markers and license light OR corrosion/wear at some point in the loop that is blocking the current.

Two, the flickering could be loose connections at various places along the way, including the ground wire. The first place to check would be the actual car to trailer connecters. Are they clean and fitting well/snugly?

I connected the trailer to the hitch and re-tested, but didn't correct my issues, but then you explained that above.

To review...
- All truck tail lights and Directional lights, License plate lights are working.
- Trailer Directional lights are working.
- Cleaned terminal pins on truck side. Clean all terminal pins on trailer harness.
- Checked ground (white wire) on trailer, all look good, clean tight and no rust.
- Truck to trailer connections are all clean and fitting well/snugly !

Going to purchase trailer/light tester at Harbor Freight, it's cheap and I need one anyway. At least testing in this manner, I can eliminate the truck connections.

Will now begin to look at ALL trailer wiring for issues.

[bigdog]

Originally Posted by bigdog

I connected the trailer to the hitch and re-tested, but didn't correct my issues, but then you explained that above.

To review...
- All truck tail lights and Directional lights, License plate lights are working.
- Trailer Directional lights are working.
- Cleaned terminal pins on truck side. Clean all terminal pins on trailer harness.
- Checked ground (white wire) on trailer, all look good, clean tight and no rust.
- Truck to trailer connections are all clean and fitting well/snugly !

Going to purchase trailer/light tester at Harbor Freight, it's cheap and I need one anyway. At least testing in this manner, I can eliminate the truck connections.

Will now begin to look at ALL trailer wiring for issues.

Bought trailer/light tester at Harbor Freight, and tested Truck plug terminals.
Left and right taillights working fine, lights on tester lit up.
The Running lights terminal tested bad, at least the light tester did not light up!

So now I'm thinking it may be a truck fuse, more to trouble-shoot !

Feedback appreciated.

[TiltonBB]

I believe you misstated. Left and right brake/turn lights are working. Tail lights
and running/marker lights are not working.

You have to have a good ground or the working lights wouldn't work so it cannot be that. All of the running lights and tail lights would not have burned out at the same time so it is either no power from the truck, a bad connection at the plug, or the main tail light feed in the trailer is compromised.

I don't know what your vehicle is but my Tahoe had a separate fuse in a different place under the hood. I think that is true of a lot of GM vehicles and maybe many others too.

[bigdog]

Originally Posted by TiltonBB

I believe you misstated. Left and right brake/turn lights are working. Tail lights
and running/marker lights are not working.

You have to have a good ground or the working lights wouldn't work so it cannot be that. All of the running lights and tail lights would not have burned out at the same time so it is either no power from the truck, a bad connection at the plug, or the main tail light feed in the trailer is compromised.

I don't know what your vehicle is but my Tahoe had a separate fuse in a different place under the hood. I think that is true of a lot of GM vehicles and maybe many others too.

Just a FYI if it helps....Truck is a 2016 Ford F150

[TiltonBB]

See if this helps.

If not, and you are still stumped and you want someone to fix it, call Nick. He is mobile and very good.

Nwmi out of Meredith 100% set up/mobile/full time & insured for this type of work.
603-520-1662.