Troubleshooting No Running Lights Functioning on a Trailer While Other Circuits Work

Question

Question:

Hello.. i just bought a 1987 Jerico 19 ft trailer trailer. . The guy said he got it rewired a month ago. I have a 2013 silverado hauling it all of the lights work great EXCEPT the running light tail lights dont work... I have a utility trailer also and all lights work when I haul it with the silverado. Please help. Going camping in a week

asked by: Daved G

0

Expert Reply:

Based on what you described it sounds like the running light circuit is somehow shorting out between the trailer connector and the light assemblies. A lot of trailer lighting issues are ground related, but since your brake lights are functioning the problem has to be somewhere on the taillight circuit itself.

I would start at the connector looking for any corrosion (fix as necessary) and then work your way back from there looking for any cut or exposed wires on the circuit to each light assembly. Since the wiring is allegedly new I would look for any wiring oversights on this circuit as well such as maybe the circuits was never even connected to the light assemblies.

I attached a couple FAQ articles on troubleshooting trailer wiring that you might find informative as well.

expert reply by: Jameson C

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Answer 1

This could certainly be a grounding issue. When a circuit does not have a sufficient ground, it can cause many different issues. If possible, I recommend checking all of the grounds for your trailer taillights. You will want to make sure the ground…

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Answer 2

It could be a tow package fuse on the vehicle. Use the owners manual to find the locations of fuses/relays related to the tow package wiring to check them and replace as needed. If the issue is not a fuse or relay then you can test the vehicle side…

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Answer 3

When you test the 4-Way on the Curt T-Connector Wiring Harness, part #56016, at the rear of your vehicle, it should show now power on all 3 pins with the lights off. If you have the vehicle head lights on, you should have around 12 volts at the…

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Answer 4

You should be getting 12 volts from each function when that function is active. The amperage will be less and can vary between functions. You can use a multimeter like #PT89ZR to check this. If you have a specific part number you want me to check…

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Answer 5

You will first want to check the fuses on your tow vehicle. Some vehicles could have fuses for operating the turn signals and brake lights of a towing package. You will want to check if they are installed and working properly. The next thing is to…

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Answer 6

Finding continuity to ground on the running light circuit of your trailer indicates that the circuit has a short to the frame of the trailer most likely and is your problem. What you'll need to do is trace the circuit starting at the…

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Answer 7

Generally you see this situation on a vehicle that has LED lights because there is a power bleed coming from a different circuit into the lighting circuit. LED lights require a lot less power than incandescents, that's one of the biggest…

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Answer 8

It sounds like the ground connection often in the mounting hardware of your lights is not connected well. This ground needs to be bare metal to metal and free of all corrosion and debris. If with a clean ground you still are not getting the desired…

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Answer 9

It sounds like there was a short or there is still a short that is causing some problems. To determine if the problem is on the vehicle side or the trailer side there is a test you can do. First unplug the trailer from your 2008 Dodge Nitro. Then…

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Answer 10

The first thing I would check is your trailer to vehicle plug. Check to see if any of the pins in the connector look corroded. If the pins look good, make sure that there is plenty of dielectric grease #LT37534 in the connection. The grease will help…

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Answer 11

The first thing we need to figure out is if the problem exists on the truck or trailer. To do this you will need a circuit tester such as #PTW2993 or a meter if you have one. Disconnect the trailer from the truck and have someone sit in the truck to…

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Answer 12

Since it sounds like you have narrowed the running light issue down to the trailer, I do have some tips for you but horse trailers don't typically have fuse boxes. If you trailer has separate turn and brake signal lights, I would first check the…

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