Both blinkers flash for right and left

[dmussell56]

On my Flagstaff T12rb when I turn on either the right or left turn signal, both right and left flash. It has a 7 pin connector as does my truck. I tested the truck to make sure that side sends iut the correct signal for right and left and it does.

When I look at the wires coming from the trailer harness there are only six wires running to the trailer. I can see the yellow wire (left turn) was cut off and is not connected to the trailer.

Is there anyway this ever worked without that wire being connected.

BTW, it was this way when I drove it off of the lot in 2021.

If they refuse to fix it under warranty is it as simple as connecting a wire to the yellow and run it back to the left rear light? Not that getting at the back light will be easy.

[dougrainer]

dmussell56 wrote:
I am learning from you people and the interweb. After a few searches I see the ESCO KAL wiring harness has 6 wires (yellow being aux), with red(LT&B) brown(RT&B), green(tail lights).

The harness wires go in to, (I wish I was smart enough to know what every part was called) a rectangular rubber "thingy", and a red, brown, green set of wires comes out the other side and goes to the back of my trailer.

Anyone who has forgotten more that I will ever know is laughing at my ignorance.

Anyway, it looks as if the right wires are indeed going to my tail light modules.

BINGO, That box is your problem. Once they went to LED trailer lights(low amp pull), some OEM's installed that box to allow the SIDE clearance lights to flash when turn signals ON. Left turn signal Left side markers flash. Right turn signal, right side markers flash. That box is defective. There should be a Brand and P/N on the box and if you are still under warranty, the OEM will replace. Doug

[BB_TX]

Can you post a picture of the “rectangular rubber thingy”?

[Tyler0215]

Why did you drive it off the lot if the lights didn't work properly??

[opnspaces]

Carefully check the cord between that box and the 7 pin plug. Is the cord or the plug cut or damaged in any way? Is the actual plug end a molded one piece Or has the end been cut and replaced?

[dmussell56]

I am learning from you people and the interweb. After a few searches I see the ESCO KAL wiring harness has 6 wires (yellow being aux), with red(LT&B) brown(RT&B), green(tail lights).

The harness wires go in to, (I wish I was smart enough to know what every part was called) a rectangular rubber "thingy", and a red, brown, green set of wires comes out the other side and goes to the back of my trailer.

Anyone who has forgotten more that I will ever know is laughing at my ignorance.

Anyway, it looks as if the right wires are indeed going to my tail light modules.

[wnjj]

BB_TX wrote:
Probably going to require pulling both taillight assemblies and do wire tracing. Somewhere both sides are tied together. Where ever they tied the left taillight to the right taillight they likely also tied the left stoplight to the right stoplight.

Agreed. I would first check up front where the 7-way cable breaks out into individual wires. Some manufacturers do this inside of a little box on the tongue frame.

[dougrainer]

I think you need to state more clearly. DON'T say flashed. If you connect 12 volts to either the Left or Right, they will NOT flash. They will be lit, but not flash. If they DO flash, with constant 12 volt, that is a whole other problem. You can have a smashed/cut 7 way cord from the trailer. Have you check that? Most common cause is the Wrong bulb/s in the rear trailer light assbly UNLESS you have LED trailer rear lights. Doug

[BB_TX]

Probably going to require pulling both taillight assemblies and do wire tracing. Somewhere both sides are tied together. Where ever they tied the left taillight to the right taillight they likely also tied the left stoplight to the right stoplight.

[dmussell56]

Tested as you said. Put wire from 12V to right blinker and both right and left lit up. Put 12V to left blinker and both lit up. Not sure what that means. 🙂

Also did same with running lights and they all came on as they were supposed to.

[dmussell56]

Tested as wnjj suggested above. Touched 12V to right turn signal and both flashed. Same with left turn signal, both flashed.

[dmussell56]

Tested as you said. Put wire from 12V to right blinker and both right and left lit up. Put 12V to left blinker and both lit up. Not sure what that means. 🙂

Also did same with running lights and they all came on as they were supposed to.

[BB_TX]

Good info above about some differences in 7 pin wire color coding.

If your clearance lights also flash then it is definitely a grounding issue.

[wnjj]

Yellow is probably reverse lights, which isn’t wired up on your trailer. Check for a good ground, the lack of which often causes the problem as one side grounds back through the other via the tail light filaments.

The 7-way cord probably follows the “RV standard” shown on this page (scroll down to the pictures): https://www.etrailer.com/faq-wiring.aspx

Test the trailer itself with the cord unplugged from the truck by jumping from the +12v pin to each of the turn signals with a paper clip.

[Grit_dog]

Check all grounds.
Yellow is aux in the other wiring convention. There’s 2 different wiring color conventions.

[Lwiddis]

If you attempt a repair the dealer may decline to fix what he/she says you broke.