Went to use t he combo the other day and no lights. Thinking my connection at the plug was not making contact I switched plugs and wiggled it a bit. Now I have brake lights and turn signals. No tail lights.

Tried another rig and all works as it should. Wiring on trailer is good to go.

My Tundra has two plugs. A flat four prong and the larger round plug. Look factory.

I had a front parking light out on the truck recently. replaced it. But now I have a door ring when I open the drive door. Never had it before so I am thinking something is not right.

All the lights seem to work on the rig. It is a previous gen Tundra.

Any help?

Thanks guys.

If one trailer works properly and the other trailer doesn't, the problem would seem to be in the trailer. I have multiple trailers and insufficient grounds often seem to cause strange problems which go away after a short drive when the trailer ball and coupler get polished up. Trailer wiring is always problematic because of infrequent use and corrosion and cheap wiring and light sockets. I try to solder all possible connections and use anti corrosion paste on bulbs and sockets.

Gene, its the truck, not trailer. We switched trucks and the second unit verify's the trailer is good to go. At least I believe so.

Yes, that is correct
bek.

Corrosion is not an issue as far as my inspection went.

Thanks.

Sounds like the plug you wiggled may be the problem. Could be the plug contacts or inside where the wires attach to the contacts.
The short version is: you'll need a test light and volt/ohm meter if it's something you can't see and obvious.

Use a test light on the plug "socket" on the truck. See if the taillights pin lights the test light. Put your taillights and 4 ways on. Two of the terminals will flash (yellow is left, green is right on the trailer wire) and one should be on solid (brown). I also concur with Gene Hillman. You might tow it around the block and fix the problem.

I don't have an answer (other than trailer lights can be very frustrating) but will add another scenario while the topic is being discussed.

I rewired a new light kit onto my trailer several weeks ago. When towed with my truck (2017 GMC) turn signals and brake lights work but running lights do not even when I manually turn my truck lights on. When my brother-in-law hooked up to the same trailer with his truck (2008 Chevy) the running lights work but brake lights/turn signals do not. I've relocated the ground wire and also tried a different hitch insert on my truck with no success.

Any suggestions?

Thanks,

Michael

Another possibility to check.
See if the ground is connected to both sides of the plug (trailer end)and socket (truck end). Sometimes someone takes a shortcut and lets the hitch and ball be the contact and after it moves around and cleans the rust or gunk off it makes the ground contact.

I sure that the ground from receptacle to truck is good. Not just test light good, all those light need to ground through that point.

I chased a similar issue and that is where it lead me. Remove the screw sand down the frame where the ring attaches and button it back up. You’ll have eliminated most trailer light issues.

Using the flat or round plug?

Both give me the same result. Matter of fact I have several of the round to flat adapters and they pretty much give me the exact same result. No tail lights but brake and blinkers.
My Tundra has the round and flat receptacles side x side with covers.

Have a multimeter?

Check the flat truck receptacle.

Odd one (white) is your ground.
Next one (brown) is tail lights/side markers.... you should be missing 12 volts on this one.
Next one (yellow) is left turn/stop.
Next one (green) is right turn/stop.

I should know whether I have one . I think I do. Will need to locate. Thanks for the direction on what to do and look for Excam Man.

Do I need to have the key on for that test? I am assuming so.

Yes, key on, lights on.

You always want to check to see if the 'odd pin' (white/ground) is still connected to the vehicle chassis ground (continuity).
I would say you do, as the other lights are working. But there's always a chance the trailer is pulling ground through the ball hitch connection.

But in your specific case, I'd say you just lost the 'power' side (brown/next to odd pin) for the tail lights.

Iirc, trailer running lights are on a separate fuse than turn/brake. I always check fuses first, then check for power coming out of the plug. if fuses are good, and no go at the plug, then I start heading upstream. There should be another multi pin connection under the bed that feeds your trailer plugs.
I had an '05 Tundra until recently, the trailer plugs used in those trucks are pretty solid and not usually a problem.

Thanks guys, once I find a multi meter I am going to check fuse's. I got the Toyota manual out of the rig and need to figure out how to get the fuse box open

I know this sounds least likely, but check the bulbs themselves first. There are two separate filaments in most of those bulbs.
Several times I've chased a problem or watched others do so, that was something really simple and wasted a lot of time before finding the problem. I know it seems unlikely that both would be bad at the same time but it happens.
While your at it maybe take this opportunity to put in LED bulbs.

When I had the trailer re-wired last year they used Led lights. So no bulbs. Thanks though.

quote:

Originally posted by 220-9er:
I know this sounds least likely, but check the bulbs themselves first. There are two separate filaments in most of those bulbs.
Several times I've chased a problem or watched others do so, that was something really simple and wasted a lot of time before finding the problem. I know it seems unlikely that both would be bad at the same time but it happens.
While your at it maybe take this opportunity to put in LED bulbs.

Did they somehow fix themselves when tied to the other rig?

What year is the Tundra?