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.

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. Time to get out your voltmeter and do some checking - here are the pinouts for the 7-pin Bargman connectors.

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.

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.

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

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.

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

15 Replies

dewey02
Explorer II
May 23, 2016
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
Explorer
May 23, 2016
Start by checking the continuity of the ground line, it's the common one to all of the above.
asullivan920
Explorer
May 23, 2016
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
Explorer
May 23, 2016
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.
SoundGuy
Explorer
May 23, 2016
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. Time to get out your voltmeter and do some checking - here are the pinouts for the 7-pin Bargman connectors.

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

15 Replies

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