No power to the trailer running lights.

[Don_in_VA]

I'm scratching my head on what should be a simple problem. On the way home from our last trip the back-up camera quit working. I put it on late last summer and we've had no issues. The error message says "No Signal". After a few minutes of trouble shooting I found the problem but not the cause. It seems when the truck is connected to the trailer the turn signals work on the truck and the trailer but the running lights on the trailer don't work (they do work on the truck). That explains the lack of a signal as the back-up camera is powered off the same circuit as the running lights. My immediate thought was a blown fuse. When I checked, all the fuses appear good. I removed each one, got a light showing an open circuit and returned the fuses one by one and the open circuit lights went off but the running lights don't work. The 12v disconnect switch is on and I'm running shore power to the trailer. We have another trip coming up next week and I expect we're legal since we'll be traveling during daylight and the turn signals work....nonetheless, I want to fix this issue. Any thoughts on what I might be missing will be appreciated.

I think this is all in my signature but the trailer is a GD 22MLE and the truck is a 2023 Tundra SR5. TIA.

 

[Bungy]

I'm scratching my head on what should be a simple problem. On the way home from our last trip the back-up camera quit working. I put it on late last summer and we've had no issues. The error message says "No Signal". After a few minutes of trouble shooting I found the problem but not the cause. It seems when the truck is connected to the trailer the turn signals work on the truck and the trailer but the running lights on the trailer don't work (they do work on the truck). That explains the lack of a signal as the back-up camera is powered off the same circuit as the running lights. My immediate thought was a blown fuse. When I checked, all the fuses appear good. I removed each one, got a light showing an open circuit and returned the fuses one by one and the open circuit lights went off but the running lights don't work. The 12v disconnect switch is on and I'm running shore power to the trailer. We have another trip coming up next week and I expect we're legal since we'll be traveling during daylight and the turn signals work....nonetheless, I want to fix this issue. Any thoughts on what I might be missing will be appreciated.

I think this is all in my signature but the trailer is a GD 22MLE and the truck is a 2023 Tundra SR5. TIA.

The running lights are powered by the truck thru your 7 pin umbilical - they have nothing to do with the fuses or anything else in your trailer.

 

[Don_in_VA]

So you're saying there's a problem with the wiring of the trailer's umbilical? This is sounding like more fun than I was planning on....

I went back out and followed the umbilical cable to the trailer and there were 2 fuses, both good based on a visual inspection. I've got brake lights and turn signals. I don't believe the trailer has backup lights. So it's just the running lights. I feel like there ought to be another fuse in the circuit that I have not found.

 

[Bungy]

So you're saying there's a problem with the wiring of the trailer's umbilical? This is sounding like more fun than I was planning on....

I went back out and followed the umbilical cable to the trailer and there were 2 fuses, both good based on a visual inspection. I've got brake lights and turn signals. I don't believe the trailer has backup lights. So it's just the running lights. I feel like there ought to be another fuse in the circuit that I have not found.

The running lights are on the same circuit as the tail lights (pin #3 I believe.

 

[kb0zke]

Our new Furrion camera has started the same thing. I have a thread on it elsewhere, but, basically, my camera worked fine in January and February. We landed at The Ranch mid-February and headed out mid-May. About a month before we left, the monitor would come on by itself and say "no signal." When we hooked up, no signal. With lights on (marker lights actually shining) I could see the blue power light on the camera, but still no signal.

If someone is at Escapade and wants to look at it they can. Otherwise, I'm tossing the Furrion camera and monitor and buying something better.

 

[Bungy]

So you're saying there's a problem with the wiring of the trailer's umbilical? This is sounding like more fun than I was planning on....

I went back out and followed the umbilical cable to the trailer and there were 2 fuses, both good based on a visual inspection. I've got brake lights and turn signals. I don't believe the trailer has backup lights. So it's just the running lights. I feel like there ought to be another fuse in the circuit that I have not found.

I forgot to mention that the brake lights and signal lights (on the same side) are on the same circuit.

 

[tfgd21bhe]

Last year I had a problem with my trailer brake lights and turn signals. Truck brake lights worked but trailer didn't. Turned out to be a fuse in the truck. The are separate fuses for the trailer connection.

 

[huntr70]

So you're saying there's a problem with the wiring of the trailer's umbilical? This is sounding like more fun than I was planning on....

I went back out and followed the umbilical cable to the trailer and there were 2 fuses, both good based on a visual inspection. I've got brake lights and turn signals. I don't believe the trailer has backup lights. So it's just the running lights. I feel like there ought to be another fuse in the circuit that I have not found.

There should be separate fuses in the truck (either under hood or in cab) that power the trailer circuits.

Just because the truck has lights, doesn't mean the trailer will. Check the fuses in the truck.

 

[Don_in_VA]

I found the problem. tfgd21bhe's suggestion made me double check whether the problem was with the truck not supplying power or the trailer losing it somehow. I got out a multimeter and found a pinout online for trailer plugs and sockets (mirror images of each other). Testing the socket on the truck, I could identify power for the turn signals and brake lights but not for the running lights. That strongly suggested the problem was with the truck. I broke out the owners manual (2023 Tundra SR5) and found 3 locations for fuses. Under the hood on the passengers side I found two likely candidates and tested the first fuse, a 30 amp low profile mini. It failed - no continuity. Toyota was kind enough to include an extra 5, 10, and 20 amp fuse but no 30 amp. A quick trip to Advance Auto to buy a new fuse and the problem was fixed...at least for now. All I've got to do is get the back-up camera sync'd to the monitor...which is proving difficult. Thanks for the help.

 

[FatTire]

Try using that electrical connection cleaner in a spray can - get it at automotive stores. Solved a
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