1) With the headlights on, the right side rear yellow light doesn't light up. If I signal a right turn, that same bulb blinks as it should.
2) With the headlights on, if I signal a left turn, the left turn (yellow) light doesn't work, but it does blink with headlights off.
Any ideas?
Lynn

 

You probably have a bulb with a shorted element or a corroded bulb socket.

 

The bulb that doesn't work when the headlights (& rear lights) is on works when I signal a right turn, so that tells me the bulb is OK. I also swapped bulbs during the test & saw that the bulb works fine on the left. There is no visible corrosion in the socket.

When the headlights are on, & I'm not signaling a turn, the left turn arrow stays lit, but doesn't flash.

Lynn

 

I posted this in another section, but I think this is a better place.

1) With the headlights on, the right side rear yellow light doesn't light up. If I signal a right turn, that same bulb blinks as it should.
2) With the headlights on, if I signal a left turn, the left turn (yellow) light doesn't work, but it does blink with headlights off.

When the headlights are on, & I'm not signaling a turn, the left turn arrow stays lit, but doesn't flash.

I could only locate a small set of fuses under the hood on the passenger side. Are there more fuses elsewhere?

Any ideas?
Lynn

 

A bulb can be bad and still work; sometimes the filament will break and fall onto another filament [happens with multi filament bulbs].
This or a corroded socket [could be the rear of the socket] or corroded connector can cause this, it doesn't have to be the actual bulb that's acting funny.
The corrosion or filament changes the circuitry, causing funny things to happen.

You need to take a look at ALL the bulbs, bulb sockets and bulb wiring connectors.
Don't forget the tow harness, if you have one.

 

Sounds like either a bad ground

A trailer conversion box problem some where wires are wired wrong or grounded wrong not a fuse problem

 

My vote is trailer conversion box. Very very common. Try unplugging your trailer lights, and just plugging the stock plugs into the lights. If the problem persists, its likely in your column switch. However, in every truck I have ever seen, its the trailer lights box.

As for your fuse question, there are fuses drivers side behind the kick panel.

 

I haven't towed anything for a few years. Does the trailer wiring harness disconnect from the rest of the wiring? If so, where do I disconnect it?
Lynn

 

you find where it splices into your wiring and remove the splices.

 

Depends on how it was wired in. Sometimes a kit is used, where you can just unplug the kit and plug the wiring back into the lights. "Plug and play"

Other times people cut/splice wiring, or piggyback wiring off themain harness, and its a mess. Only way to tell is remove your taillights, and see what has been done.

 

Thank You! Thank You! Thank You!

I disconnected the tow wiring harness & the lights work as they're supposed to.

I appreciate the help I've received here on this forum. You guys rock.

Lynn