Towing Blinker Not working

On my RV everything works but the left blinker. The running lights are working, just not the blinker. To eliminate the RV I plugged my other truck into it and the blinkers worked normally. I checked all the fuses in the box under the hood. Has anyone seen this and know what might be the problem.

 

Does the turn signal on the truck function properly? Is it only the turn signal, or does the left hazard not work either? I know it's the same bulb, but it's usually wired as a separate functionality in the plug.

If it does, then I'd guess it's something in the plug on the truck. Check to be sure it's clean and free of corrosion. Hell, I've had dead earwigs and other bug corpses cause issues in vehicle trailer plugs before. Barring that, you might check the voltage to the plug. Loose or damaged wires on the back side of the plug would be the first thing I'd check.

 

the turn signal on the truck does function properly, it's just the trailer. I have not checked the hazards. I'll definitely try that. I have checked the fixture on the RV. it appears to be fine.

 

Check wiring behind the bumper for rodent damage. As said above, check the pins on the plug for voltage using a test light or meter. Pretty sure you have a bad connection at the plug or a damaged wire leading to the plug. Is the ground connection getting lost? Check that too.

 

I should clarify, in my previous post when I said the "plug" I was referring to the truck side.

 

BTW Walter, welcome to the forum!

 

Thanks, I practically stole this Tundra from a car dealer in full panic mode at the beginning of the lockdown in 2020. I should be ashamed of how little I paid for it. But.... at that time none of us knew if we'd be living in caves in a few months.

 

My trailer plug only has left and right. Blinkers and hazards are on the same wires. I have never seen it any other way. When I have problems with blinkers I use the hazards to diagnose because they work without the key on.

 

Unless I am mistaken the turns are also the brakes on these trucks. That is how mine is anyway.

 

Correct

 

Gratitude to you folks for helping, I did another trip this weekend and tried the hazards and as you say the hazard on the left side does not work. I have checked every fuse under the hood three times, the plug itself appears to be undamaged. Any further suggestions?

 

Did you check for voltage at the pins? Set meter to dc volts and turn on the lights to verify you can find a good ground and the meter responds. Then turn off parking lights and turn on flashers. Check for voltage. It should go up then to zero with each pulse or flash if not the problem is in the truck wiring if it does you have trailer wire or bulb poblem. To check for bulb problem move good bulb from other side or check socket for voltage with the meter. You will obviously need to plug in the plug and turn on the lights again to verify meter response and so on.

 

I checked it, there is voltage measuring at the pins, but it seemed really low. like it shows 0.04 then zero then back to 0.04. I tried the same test on my chevy which has a similar plug and I know does work with the trailer. It shows 4.0 something blinking on and off. so it seems like the tundra is not producing enough voltage, what would cause that?

 

A dirty or corroded plug connection somewhere along the harness could be the issue.

 

Check your pin voltage for opposite side to compare

 

Nix the idea of using a meter for troubleshooting these types of circuits. Use the test probe with a light in the handle and alligator clip on the lead for grounding. Words from a wise mechanic (my Dad) " You can read voltage through horse piss but you'll never see any current flow." The test probe tests for current capabilities.