Towing light works only when hitting the brake

I was working on my friends trailer lights. I made it work but then the ground connector on the adapter broke. After that the lights did not work until i hit the brakes. While the brake pedal is on the lights are up, once the pedal is off so are the lights. It is most likely one of the fuses. Just not sure which one. Any advice is welcome. Thank you

 

Um, have you tried fixing the ground ?

 

I am not typing much tonight .
Therefore .....read your bible my son
https://www.tacomaworld.com/threads/the-tacoma-towing-bible.4031/

 

If it is a fuse.
I’d look at the 30A Trailer Tow Fuses.

 

Im pretty sure it is not the ground issue, since the lights show when i hit the brakes.

 

I checked out all the towing and tail related fuses. In both fuse boxes. They are all fine. None is blown.

 

Check the bulbs.

These are typically dual element bulbs. One element for running lights, the other for brake/signal lights. It is plausible that when the GROUND was broken that it blew the running light element.

Oh.....fix the ground.

 

Buddy, i need to find an answer to a simple question, what could cause the trailer lights not work in regular mode but work when i hit breaks. And you are telling me to browse Brittanica Encyclopedia. If you dont know the answer, it is ok but dont make me read through bunch of irrelevant posts on how much my trailer or Toyota can haul or what load can damage my transmission.
Otherwise thank you.

 

I tried it on my boat and jetski trailers, same result. It just drives me nuts, since the answer would be pretty simple but i cant figure it out.

 

I dont know the answer without asking you to perform some simple tasks and answering some simple questions .
Golly , I apolgize for upsetting you . Ty che, bylad . I have always passed the towing bible on to " NEW " members .
99% of the time ,all the answers are in that thread and I can promise you that your answer is on the first page
You mentioned any advice was welcome .

You mentioned you were working on your friends trailer . Does this mean you were using your truck to test the trailer lights on your friends trailer ?
You mentioned a ground wire on the adapter broke ? was this a 7 pin to 4 pin adapter or does your friends trailer have trailer brakes ?
You then said after the ground wire broke , the brake lights only come on when you hit the brakes . What lights ? the truck brake lights or the trailer brake lights ?
Are you running a brake controller ?
One of the guys asked if you fixed the ground . You replied that you were pretty sure its not the ground because the lights show when you hit the brakes .
The ground needs to be fixed or your voltage will backfeed through another circuit .

What lights are illuminating when you hit the brakes ? the running lights or the brake lights ?


Do you have an OEM manual for your truck ?
Do you have a test light ?
Do you have a volt meter ?

If you have a test light , with your lights on ,what happens when you probe the brown wire at the vehicle connector ?
With your right signal light flashing , what happens when you probe the green wire at the vehicle connector ?
With your left signal light flashing , what happens when you probe the yellow wire at the vehicle connector ?

 

Are you saying your turn and stop lights work?
But the RUNNING lights do not?

If so, you need to see if the Pin marked TAIL Lamp on the connector is getting power.
Turn your tail lights on, use a test light to see if this pin has power.
If so, your problem is the trailer adapter, or the trailer wiring.
Might as well check the Ground Pin while you are at it.




If it does not have power, I would check the Towing Tail Relay.
Remove the Relay, turn ON the Tail Lights.
CHECK Pin 2 and 5 for POWER.
CHECK pin 1 for Ground.

 

Thank you guys, that gave me the starting point, of where to look for an answer. Sorry for a brush response gearcruncher, i was just getting frustrated and honestly speaking, did not think logically. I was just driving my friends trailer at night and noticed no running lights, while there was light turning on when brake pedal was pushed. And i know the trailer lights were working before because i did change the rear lights on this trailer, replaced the broken one and I used this trailer twice for towing 3 or 4 loads with all lights working well. Upon check the adaptor's ground connector was broken, but the lights were still dead and getting lit when break pedal was pushed. I tested it again on my boat trailer with exactly the same result. But again i did rush and did not test what was lit exactly. Will check them with my friend to see exactly how do the lights work and then check the voltage on the trailer hook-up connector and then on a new adapter