Trailer driving lights do not work, what I've done so far...

[wolfee]

Left Turn, right turn, brake all work fine. Driving lights do not work.
1. I tried a different (new) trailer tail-light, same thing.
2. Cleaned the ground near hitch as well as the ground at the tail-light. (same thing)
3. Ran my own trailer wiring harness from the truck, grounded to trailer. (same thing)
4. Bought a new connector (7- connectors at truck to 4-flat) (same thing)
5. Bought at 4-flat tester that you plug into the connection at the truck. The tail light connector does NOT light up. Left turn, right turn light up.

So it's on the truck side?? I've never dealt with this before and have spent all day troubleshooting this. I know Auto Zone has a universal 7-connector piece for the truck but how do I know that's the problem? Can anyone give me some steps to figure out where the problem is? I'm going to Canada next weekend and this is getting annoying. Any help appreciated.

 

[alldodge]

What Truck?

 

[jimmbo]

To the Tail Lights work on the Tow Vehicle?

If they do, could be a Misswired Connector on the Tow Vehicle, or a Broken wire to the Connector

 

[Scott Danforth]

Many trucks have separate fuses for trailer lights

 

[wolfee]

It's a 2014 Chevy Silverado, 4x4. Yes the tail lights work on the Truck. I turned the headlights on, tail lights come on, do not turn on on the trailer. I did have to bring the truck in for wiring issues (mice) maybe 1/2 year ago. Not sure how to find where the failure would be on the truck.
Note: the wiring issues were on the truck's engine area, not trailer/connector issues.

 

[jimmbo]

Follow the Wires from the Connector back
Check the 7 pin Connector for Power when the Tail/Running Lights are on. Perhaps the Wire is on the Pin for you Adapter to work
Worse comes to Worst, you can always, splice into the wire that feeds the Tail Lights.

 

[alldodge]

Have a look here
https://www.gm-trucks.com/forums/topic/189264-trailer-lights-dont-work/

 

[04fxdwgi25]

Fuse #15 in the engine compartment fuse box is for trailer parking / running lights.

Fuse Box Diagram Chevrolet Silverado (mk3; 2014-2018)

Fuse box diagram (location and assignment of electrical fuses and relays) for Chevrolet (Chevy) Silverado 1500/1500HD/2500HD/3500HD (mk3; 2014-2018)

fuse-box.info

Your owner's manual should have all the info.

 

[dingbat]

The 7 pin on the truck is wired to the AISE standard. Look on the spring loaded cover of the connector to identify which wire (typically brown) is powering the tail and running lights.

To eliminate the 4 pin being the problem, probe the appropriate pin in the 7 pin and ground (white) for power in

If you have no power there, remove the harness connector from the back of the seven pin.

If not there, move to the connector on the next harness up the chain.

This document contains the schematics for the entire trailer connector circuit. Includes fuse identical and locations. Should be a piece of cake to troubleshoot from here

https://www.gmupfitter.com/wp-content/uploads/2021/06/Sierra_Silverado_Electrical_Body_Builders_Manual_Service_Manual_2015_en_US.pdf

 

[wolfee]

Thank you all, trying to work this out today. @dingbat I have a 4-flat tester that plugs into trailer-side of the 7 pin connector. The tail light blade is dead. The L-turn, R-turn both work. Trying to figure out which fuse is which atm. Checking the URL listed above.

 

[wolfee]

Finally found fuse #15 and it IS blown. That's good and bad. It's a 20 fuse, gotta go get some but then I might find out why it's blown. Thank you all so much! Gotta get this done!

 

[jimmbo]

One way to reduce the Odds of it blowing again, is to unhook the Trailer Lights, just before you put the Trailer in the Water. Regardless of how "Water Tight" the wiring is supposed to be, it rarely is, and undistilled Water, is an excellent Electrolyte.

 

[airshot]

Even with LED water proof lights I still unplug when backing into water, old habits die hard and some old habits are still good !!

 

[Lou C]

They make led trailer light receptacle testers that are nice to have, I made up a couple of 4 flat harnesses for my trailer with this built into the end of the harness so you can see if the trailer lights are getting voltage without walking around the back of the trailer.

 

[wolfee]

Wow, I've never unplugged the lights before backing the trailer into water. I'm an idiot, doh! Awesome suggestion, I'm always thinking of something else at that point.

 

[JASinIL2006]

About the only good reason to unplug the trailer us if you have incandescent bulbs, which might pop from temperature shock. I’m guessing most trailers get pretty much of the time, and I don’t believe everything will dry out that quickly after having been dunked. I don’t know of anyone who unplugs their trailer when launching, and all of my friends are exclusively trailer boaters. Maybe it’s different if you boat in super salty water, but I don’t believe that would make that big of a difference either.

 

[roscoe]

About the only good reason to unplug the trailer us if you have incandescent bulbs, which might pop from temperature shock. I’m guessing most trailers get pretty much of the time, and I don’t believe everything will dry out that quickly after having been dunked. I don’t know of anyone who unplugs their trailer when launching, and all of my friends are exclusively trailer boaters. Maybe it’s different if you boat in super salty water, but I don’t believe that would make that big of a difference either.

Same here.
True, you may get a little electrolysis if the water is in a connection ( a poor connection ) for a long enough period of time.

But it will not cause a short and blow a fuse.
Fresh water is simply to poor a conductor to do that.

You could set your battery in the lake, or flood the battery compartment, and nothing would happen, except embarrassment from forgetting to put the plug in. What ? Who? Me?

 

[tpenfield]

Wow, I've never unplugged the lights before backing the trailer into water. I'm an idiot, doh! Awesome suggestion, I'm always thinking of something else at that point.

I usually forget, but it is a good idea.

 

[roscoe]

I kind of like my electric trailer brakes to work while backing down the ramp.

 

[alldodge]

Once the weight of the boat is enough to pull it elf down the ramp I put tranny Drive and let it cost. All ya have to do is give it the slightest bit of gas to stop or slow the decent