I'm assuming this is a wiring problem. I had a fast blinker on one side, sometimes...replaced the bulb. Still fast sometimes. Now I have both left and right fast blinkers, but only occasionally. I'm assuming wiring, but my electrical trouble-shooting skills are pretty weak. I have a volt meter.

Where should I start looking, and how do I track this down?

 

Try pulling the fixtures off the truck, and check the ground to the body on the back? They are prone to corrosion. and thus you get the rapid flash.

Worth a look...
Pat☺

 

Thanks! I'll check the connections soon. Been rainy and I don't have access to a garage right now. At the same time, I've been noticing my brake light coming on now and then, which is what made me think it might all be connected and be wiring, but they may be separate issues.

 

Hard to say for sure what the blinker issue was but I cleaned all the connections in the actual blinkers, and replaced the front right assembly since the lens was cracked a moisture was getting in. That solved the occasional fast blinker. Brake light was from slightly low brake fluid. It all seemed to happen at once so I was thinking there was something bigger going on with the electrical system, but luckily not.

 

Didja add the required blinker fluid?

 

I check that before every drive.

 

Try disconnecting the trailer wiring 5 wire to 4 wire converter, maybe it is effecting things, they do go bad as an add-on over time.

 

Thanks Malcolm. I actually remember reading the reviews for the trailer wiring before I bought it, and a few mentioned their experience that they go bad every few years, so to expect it. Mine's going on 7 years so it's likely time...

But so far, my issue seems fixed.