Trailer lights going bonkers

[trob445]

I put a T-connector on my pathfinder this past weekend and here is the issue. **Note** My buddy and I picked up the boat with his truck and the lights worked fine on his Highlander... I have taken checked my connections on the tow vehicle and traced everything to make sure the connectors are correct. (kind of hard to screw these up as they are just in-line connections to the existing plug)

With the lights on the tow vehicle off and vehicle running - my driver side trailer blinker and brake lights work
Turn tow vehicle lights on - blinker stops working and no brake light when brake is pressed

Tow vehicle lights on - passenger side trailer light red and good to go - brake light works when brake is pressed - BUT no blinker

running lights under trailer work regardless of lights being off or on. - Ground is connected to ground screw in tow vehicle and ground has good clean connection to trailer via bolt on tongue.

Sanded down male and female connections at the hitch and tongue. With conduit tester I get light on ground from both connectors.

Has to be a ground issue.....

Thoughts?

 

[Loggerhead Mike]

If all is working at your trucks harness disconnected, how is your trailer grounded? White wire free or grounded to trailer frame? Wich ever way it is, switch it.

Had same thing when I first baught my rig

Vehicles are either frame or circuit ground, most new are circuit.

 

[user 7806]

Bad ground can cause all sorts of strange things to happen. Don't rely on the ball & coupler for the ground.

To make sure the plug on the truck is working correctly get a plug tester, they are a few bucks at a auto parts store.

 

[Wallijig]

X3 on ground issues.
I had same problem on trailer I borrowed from guy. Would work on his truck, but then would not on mine. However my boat worked on my truck, and his truck both. We first redid all grounds to frame of trailer at lights and at hookup, did not help. Instead of relying on trailer frame, I run a ground wire to tie in all grounds as well, it took care of problem. Frame built up some type of resistance somewhere causing issues.

 

[AB14]

I had an 05 chevy half ton that had fuses for every light that would hook to the factory wiring harness. I also put a "T" in my harness and not many of the lights worked on the trailer until I found the blown or missing fuses under the hood. Look in your owners manual or under the hood. The fuse boxes should have a diagram of each fuse in that box on the lid. Good Luck.

 

[Zum]

If they worked(trailer) with your buddies truck,most likely not the trailer.
Use a mutli meter to test(or test light) and check at your truck connector.
Maybe ground or fuse.
If you want to test your trailer for fun...you can use a battery charger.
Neg.terminal to trailers ground--
Pos.to brown wire(use a small nail)running and side marker lights...
then try the green and yellow wires...brake and turn signals,normally brighter.

 

[Sawdust Farmer]

If they worked(trailer) with your buddies truck,most likely not the trailer.
Use a mutli meter to test(or test light) and check at your truck connector.
Maybe ground or fuse.
If you want to test your trailer for fun...you can use a battery charger.
Neg.terminal to trailers ground--
Pos.to brown wire(use a small nail)running and side marker lights...
then try the green and yellow wires...brake and turn signals,normally brighter.

+1. Yellow = left, Green = right; New electronic battery chargers may not work for this as they have to sense at least a slight voltage before they will put out power. You can just use jumper wires from a battery (tow vehicle, lawn mower, boat, etc.) be sure to fuse one of the jumpers in case you find a short circuit somewhere.

sf

 

[lovedr79]

Another vote for bad ground. Seen it many times.

 

[nlester]

I rewired my trailer and installed new lights. One light blinked, the other did not. After spending a lot of time trouble shooting wiring, I discovered someone at the factory had jammed a lightbulb in the wrong way I got the light out, turned it 180 degrees and pluged it back in. Everything worked except one prong on the lightbulb was damaged too badly to hold the bulb in securely. Oriley's auto parts said that could not have happened at the factory.

 

[GYPSY400]

I put a T-connector on my pathfinder this past weekend and here is the issue. **Note** My buddy and I picked up the boat with his truck and the lights worked fine on his Highlander... I have taken checked my connections on the tow vehicle and traced everything to make sure the connectors are correct. (kind of hard to screw these up as they are just in-line connections to the existing plug)



Thoughts?

What year is your vehicle?? The newer vehicles with a body control module that control the lights may be the issue.. Although you might have a kit that fits the plug you tee'd in, the BCM may think somethings faulty thus giving mixed signals.. Usually a bad ground on a trailer causes the signal lights to work, but not the running lights, it would use the running light circuit as ground when using the signals.
So check to make sure your vehicle is putting out the proper signals at the trailer plug, and make sure it's properly grounded at the vehicle - which is not necessarily the frame ground.

 

[trob445]

Thanks for the input, fellas! Hoping to get back on the issue this week. Its been crazy busy here.

**and make sure it's properly grounded at the vehicle - which is not necessarily the frame ground.

Other than the existing ground available where my taillights are grounded. What am I looking for? (I know.. I know.. I should know this)

 

[sawmill]

I vote for a ground issue also. Did you get the wire from the plug to the trailer that matches you tee you put into the wire harness on your truck. If you used one that is not the same brand this could be your problem. I had one on a new Chevy truck that the white wire was not the ground and it caused all kinds of fuse problems.

 

[Bob Landry]

Why is anyone troubleshooting lights on a trailer that works on one vehicle? If the lights work when connected to ANY truck, the the trailer is fine. Also, it's unlikely that the trailer is depending on the connection at the ball and hitch to get ground. That's what the white wire on the plug does.

 

[Frogman Ladue]

I put a T-connector on my pathfinder this past weekend and here is the issue. **Note** My buddy and I picked up the boat with his truck and the lights worked fine on his Highlander... I have taken checked my connections on the tow vehicle and traced everything to make sure the connectors are correct. (kind of hard to screw these up as they are just in-line connections to the existing plug)

With the lights on the tow vehicle off and vehicle running - my driver side trailer blinker and brake lights work
Turn tow vehicle lights on - blinker stops working and no brake light when brake is pressed

Tow vehicle lights on - passenger side trailer light red and good to go - brake light works when brake is pressed - BUT no blinker

running lights under trailer work regardless of lights being off or on. - Ground is connected to ground screw in tow vehicle and ground has good clean connection to trailer via bolt on tongue.

Sanded down male and female connections at the hitch and tongue. With conduit tester I get light on ground from both connectors.

Has to be a ground issue.....

Thoughts?

I had to read this a few times, and Im still not getting the whole picture. Does the tow vehicle have any issues with it's light functions, when the trailer is attached and connected?

Did the harness you install have a turn signal isolator? I know you need one for the Xterras, which is almost the same vehicle.