Need a battery in your TT for your tail lights to work?

[2lazy4U]

I have a feeling this is a dumb Q, but so be it. I have a bad battery in my TT, and the taillights/blinkers etc. don't work. I removed the battery, but the lights still don't work when plugged into my 7 pin car connector with the car on. My car lights all work fine.

Should the lights work directly from my car's 7-pin plug even w/o a battery in the TT, and I therefore have two separate issues? Thanks.

[Mark_and_Linda]

Thanks for the follow up on your problem...don't jump to conclusions, check the fuse. If mine does this...I will surely check the easy thing first.

[2lazy4U]

Aha - it was a blown fuse. Thanks everyone, I learned a lot here.

[thomasmnile]

bigrigfixer wrote:
Have you checked the fuses in your truck yet?

X2. First and easiest thing to check. If blown replaced and blown again, the detective work with the multi-meter begins searching for the 'why'.................

[2lazy4U]

My trailer weighs 1500# and my truck is rated to tow 5000# and weighs 2 tons. But I'm selling the trailer anyway, so won't be pulling it, just want to get it all operational. It all worked fine when I parked it, so I suspect it's in my truck, as I have a small cargo trailer and the lights in it are suddenly not working also. Thanks, y'all.

[beemerphile1]

2lazy4U wrote:
Yes, I'm getting a new battery ASAP, though Colorado state law says you don't need brakes if your trailer weighs under 3000#. But I prefer to have brakes, having had to make a couple of quick stops in the past, which wouldn't have turned out so good w/o brakes. Thanks, all.

Quite likely true but we have no idea what you have since your signature and your profile are blank.

The law probably also states that if you do have brakes, required or not, all parts of the system must be functional and the breakaway is part of the system.

[2lazy4U]

Yes, I'm getting a new battery ASAP, though Colorado state law says you don't need brakes if your trailer weighs under 3000#. But I prefer to have brakes, having had to make a couple of quick stops in the past, which wouldn't have turned out so good w/o brakes. Thanks, all.

[beemerphile1]

Old-Biscuit wrote:

2lazy4U wrote:
Thanks for all the replies. I'm going to check fuses and all in the morning. I've been down lots of dusty roads the past month and dirt may be a contributing factor. After checking fuses, I'll spray it with contact cleaner and check ground wire continuity. Thanks again, everyone. This forum is great.

And hopefully buy/install a new fully charged battery in your TT!!

Federal Law requires a battery to provide FULL 12V DC Voltage to trailer electric brakes for at least 15 minutes in the event trailer should become disconnected from tow vehicles umbilical cord (brake controller input)

I second this, Please insure that your breakaway braking system is functional with a good battery. It is the law and a service to other road users.

[Old-Biscuit]

2lazy4U wrote:
Thanks for all the replies. I'm going to check fuses and all in the morning. I've been down lots of dusty roads the past month and dirt may be a contributing factor. After checking fuses, I'll spray it with contact cleaner and check ground wire continuity. Thanks again, everyone. This forum is great.

And hopefully buy/install a new fully charged battery in your TT!!

Federal Law requires a battery to provide FULL 12V DC Voltage to trailer electric brakes for at least 15 minutes in the event trailer should become disconnected from tow vehicles umbilical cord (brake controller input)

[2lazy4U]

Thanks for all the replies. I'm going to check fuses and all in the morning. I've been down lots of dusty roads the past month and dirt may be a contributing factor. After checking fuses, I'll spray it with contact cleaner and check ground wire continuity. Thanks again, everyone. This forum is great.

[bigrigfixer]

Have you checked the fuses in your truck yet?

[dewey02]

This is not an unusual circumstance in areas of the country that have bad winters. A lot of road grime and salt can get into the connector on your tow vehicle and cause bad contacts. I usually spray it down real well in the spring with electronic contact cleaner (and spray and brush the contact on the male end as well). This often takes care of the problem.

[horton333]

Start by checking the continuity of the ground line, it's the common one to all of the above.

[asullivan920]

Your trailer lights are not connected to the battery and should work when the 7 pin is connected to your vehicle. But I believe you need a charged battery for your trailer brakes to work in the event of a brake away.

[2lazy4U]

SoundGuy wrote:

2lazy4U wrote:
Should the lights work directly from my car's 7-pin plug even w/o a battery in the TT, and I therefore have two separate issues?

Yes to both ... your trailer battery, or lack thereof, has nothing to do with the trailer's running / brake lights.

Thanks, I was afraid of that.