7 Pin Connector Questions/Issues - Trailer Interior Lights

(cross posted from ask a Toyota mechanic)

I need a little help with the 7 pin connector for the trailer. I have a car trailer with interior lights that don't work. They didn't work with my Tacoma either. BUT, I wanted to make dead sure the truck isn't the problem (trailer is offsite right now). Pin on the connector 4 appears to be hot when the engine is on. Pin 7 never appears to be hot.

I read on some horse trailer forum, they had a similar issue with their truck (not a Tundra) and a fuse needed to be installed to make the trailer interior lights work. I don't know which pin my lights work from (will investigate later) but how do I get a signal out of Pin 7?

thanks!

 

Pin 7 should be the reverse wire. You should have the trailer side interior lights to pin 4.

https://www.ajtnt.com/7-way-rv-plug-diagram/

 

Multimeter and a second person to test functions.

I worked at a rental company with trailer mounted pumps and generators. Somewhere north of 100 total trailers. When I first got there I swear every truck and most trailers were all wired in a different configuration. But then I also found about 5 different 7-pin diagrams laying around from different trailer and lighting manufacturers.

The only real way to be sure is to test your truck and your trailer, pin for pin.

 

Perfect! Thanks.

Yeah, I tested with a multimeter and my 12 year old son stepping on the brakes and working the lights. No way would I be behind the truck testing it in reverse. (and didn't think to do so!).

I possibly have an issue in my trailer (it's old), but I wanted to make sure I knew where it was supposed to get power from first.

 

Ditto

 

To test reverse turn key to on, apply brake, and throw shifter in reverse . Engine does not need to be running. Did this when I installed LEDs and when I installed back up lights on trailer. Came to me over a beer.