Trailer Harness issue

I have a 2000 SR5 4x4 with a factory installed 4 pin trailer harness. When I hook up the trailer harness to the truck harness everything works but the right turn signal. The trailer harness checked good, any ideas what could possible be the issue?

 

Check the ground. Then wiggle the connection. Then pull bulb on trailer to verify it's good.but like 90% of trailer light issues is ground.

 

so you tested the plug at the back of the truck and all wires/connections tested good?

^ check the connections on the trailer wiring.

 

I had the same issue....I had to put a new tail light converter in. It is what is tapped into the tail light and connects to the 4 pin

 

Time to break out the Meter and do some trouble shooting

So many things it might be .

the bulb

a corroded socket. Not allowing a good ground.

corroded plug

damage to wiring someplace.

 

Do you have a meter and a safety pin? Pierce the coating on the green wire before the plug on the truck. If that one is not showing voltage, then the above is the correct answer. The converter boxes are the weak link.

Do these test, a digital multi meter is not your friend. Ghost voltage will mess with the meter. They are just too sensitive. I like the good old fashioned analog multimeters for this application.

 

Might check the fuses that run off the converter box also. I have the whole set up on here for sale and didn't realize there were fuses on the lines. each one has it's own fuse.