Left turn signal and brake light malfunction

[Sloughpump]

Left turn signal and brake light malfunction

2013 Laredo TT 296 RL; 2011 GMC 2500 Denali

I reviewed another string on this subject that didn't help me. Bulb was replaced and also checked on right side. It works there. Checked circuit fuse box under the truck hood. It was blown. I replaced it again. I used a test plug on the truck recepticle. All lights appeared to work as normal. Plugged into the trailer and tried left signal and brake. Still out. Rechecked truck fuse, it was blown again.

I believe the problem is in the trailer wiring, for the trailer-side plug back.

Is there a powered, test recepticle available to check the trailer lights without it being plugged into a vehicle?

If the fuse blows each time, I don't know how to check the wiring, other than a painstaking visual, and a short may not be visible. And correct me if I'm wrong, but doesn't that also require dropping the coroplast on at least the left/street side?

Thoughts? Thank you all.

[flybouy]

Left turn signal and brake light malfunction

2013 Laredo TT 296 RL; 2011 GMC 2500 Denali

I reviewed another string on this subject that didn't help me. Bulb was replaced and also checked on right side. It works there. Checked circuit fuse box under the truck hood. It was blown. I replaced it again. I used a test plug on the truck recepticle. All lights appeared to work as normal. Plugged into the trailer and tried left signal and brake. Still out. Rechecked truck fuse, it was blown again.

I believe the problem is in the trailer wiring, for the trailer-side plug back.

Is there a powered, test recepticle available to check the trailer lights without it being plugged into a vehicle?

If the fuse blows each time, I don't know how to check the wiring, other than a painstaking visual, and a short may not be visible. And correct me if I'm wrong, but doesn't that also require dropping the coroplast on at least the left/street side?

Thoughts? Thank you all.I'd start with easy to access places first. Use a VOM and check umbilical. Typically it runs into a connection box under the front. Then remove tailight and see if the short to ground clears. Good luck.

[hankaye]

Sloughpump, Howdy;

Normally I don't get in to electrical as I'm not happy dealin' with it.
Some folks have used a round "Blinker" relay to 'Light up their units for
emergencies or just a decoration by way of pluging it into the Trailers plug end.
Now this from what I remember just does the "Running Lights" so perhaps may
not allow the Brake/Turn light to light Y might get them to illuminate by using a
test light with the griping end (alligator clip), in the power slot then stick the
probe into the problem slot. Might be good to have someone there to let ya
know one way or the other it works or not.

However from what you are saying I'd be checking from the Tow vehicle's outlet
plug back to the fuse that keeps blowing. Chances are that you've got a section
of wire that's rubbed and is shorting out.

Anyway, Please let us know what ya find...

hank

[Ken / Claudia]

Good news, it's a short. Bad news where. As mentioned start at the taillight.

[FlyingAroundRV]

If it repeatedly blows the fuse, there's a short.
Don't be tempted to try to brute force it by powering it directly from a battery etc. Fuses are there to stop shorts from causing fires. If you bypass that safety mechanism, the fire department may be the ones to tell you where the short was.
There is no shortcut for this. You'll have to remove some covers etc to find the culprit. My bet is a wire has been laying across a sharp edge going through a pass through hole in the frame and the insulation has chafed through.

[UsTwo]

I agree that its probable a short.. I just went through this and found out mine was the fuse.. I replaced bulbs and the truck plug in.. then went to Harbor freight and bought a Curt Seven way round plug tester. it was cheap but I felt it let me know it wasn't the trlr nor the plug in on the truck..

[Sloughpump]

Thanks. I'll give it a try....

[Sloughpump]

Will do... She's stored now...winter in Minnesota!

[hankpage]

On the A-frame is a junction box at the trailer end of the umbilical. I would start there and look for connection that has come apart and grounded. The problem is in the left turn circuit. There is no "brake light" wire, it is left and right turn combined. JM2¢, Hank

[hornet28]

Just so there's no confusion. hankpage meant the brake/turn is combined for each side.

[Wing-in-it]

beleive it or not it could be as simple as the bulb, I’ve seen it happen before.

Easiest fix too if it is the problem.