Trailer lights not working

H

Hoop

Member
I picked up a used 2017 SR5 a month or so ago, and when I tried to hook up a small boat trailer none of the lights work. When I hooked up a different trailer the turn signals/brake lights work but not the tail lights.

It appears I have two issues. The boat trailer has its own issue that I will need to sort out, but the 4Runner has an issue with the tail light circuit. I tried a 7 pin to 4 pin adaptor and had the same results as just using the 4 pin. Is there a fuse for the trailer lights that I should check? I am stumped...
 
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Get a test light or they have a plug in tester and make sure you're not trying to fix something that isn't broke. I've had this problem in the past and it's always been a trailer issue. Not sure if there is a fuse or not but it'll be on the lid if there is. Good luck.
 
Thanks, and I did plug in a tester and it lights up with the brakes and turn signals but not with the tail lights.
 
I suggest you first get a pin-out of the 4Runner connector. If you can't find one - then get a meter and make your own by operating brake, tail & turn signal lights while probing the connector. Once you have that, you can compare the trailer wiring to the 4Runners connector. Keep in mind that some connectors share wires for some functions. Chances are the trailer wiring doesn't match the 4Runners connector and or the trailer has a problem.
 
There is one pin on the tester that never lights, but the other two will light with the brakes and turn signals. When I hooked up a different trailer I had the same results: brakes and turn signals but no running lights.

There is a large relay in the fuse box that the lid says "towing tail" on. Could the relay go bad and allow turn signals and brake lights but not running lights?
 
Whelp, used a little Google Fu and found the exact problem being discussed on this forum a few years ago. I found a blown 30 amp fuse, which I am sure is the
issue with the 4Runner.

Now I can start trouble shooting the trailer...
 
Hoop said:
Whelp, used a little Google Fu and found the exact problem being discussed on this forum a few years ago. I found a blown 30 amp fuse, which I am sure is the
issue with the 4Runner.

Now I can start trouble shooting the trailer...
Click to expand...

I have this exact problem, which 30 amp fuse is blown? I checked the trailer with another car and all the lights work. So it is the 4Runner that is the problem.

Thank you,
Bill
 
BillyBoost said:
I have this exact problem, which 30 amp fuse is blown? I checked the trailer with another car and all the lights work. So it is the 4Runner that is the problem.

Thank you,
Bill
Click to expand...

Time to grab your manual and find the trailer fuse.
Maybe in the drivers side fuse box left of the steering wheel.
 
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