lights on trailer acting funny

[treegump]

To begin with - when I originally bought the truck, it had a 7 pt plug and a 6 pt plug on the hitch, and a 6 pt plug in the bed for the gooseneck. The 7 pt plug was corroding in the back of the plug, the 6 pt plug on the hitch was corroding inside at the terminals, and I never pull a gooseneck...and I don't have an extension, so its never used.

I pulled a 18' car hauler back to my house around Christmas time and the 7 pt plug went to crap - it melted the aux & the other top terminal together on both the truck side and trailer. I have since ripped out all the misc/extra wires and am have correctly wired a new 7 pt receptacle on the hitch (as the multiple diagrams show), and the trailer is wired correctly -as far as I can tell. (wires match to the correct terminals). ( I know that the truck side is wired correctly because I took my voltmeter and attached my black wire to the ground, and with my truck shifted in reverse, with the left turn signal on, with parking lights on, I received current from all 3 of those terminals).

My problem - when I turn on my left, right turn signals, all the lights blink - the marker lights, turn lights, brake lights, license plate lights - ALL blink. When I apply the brakes - they appear to work fine. When I turn off my parking lights to the truck, my trailer lights stay on.

Where should I start looking? Is there a fuse somewhere that could have blown and causes the lights to stay on for safety purposes? Please advise - thanks!!

 

[whatnot]

Are you sure you didn't wire it backwards? If you did get the ground and aux backwards it would probably do that but would blow the fuse as soon as the trailer hitch and truck hitch touched. Do you have a meter to check it? If the lights are staying on, find which pin has 12v on it.

 

[treegump]

Are you sure you didn't wire it backwards? If you did get the ground and aux backwards it would probably do that but would blow the fuse as soon as the trailer hitch and truck hitch touched. Do you have a meter to check it? If the lights are staying on, find which pin has 12v on it.

wow...I didn't even think about checking for 12v when my parking lights were off but the trailer's weren't. This is what happens when you start testing stuff at 1 in the morning, haha. And as far as the ground and auxiliary - I'm sure, because I don't even have the aux hooked up in the engine compartment - blew a fuse trying to figure out my brake controller (which is also not hooked up yet).

 

[whatnot]

If it wasn't for the lights staying on then I would have said to check the ground.
I would start by checking what the plug on the truck is putting out when the brake is applied, when everything is off, signaling, etc.
It should match the picture on the right side if checking inside the plug.

 

[trouttrooper]

if you have a poor ground the current will sometimes try and use a different route to complete the circuit which can result in some straaaange things.

I had an old horse trailer that looked like I had wig-wags for the taillights when I had the hazards on.

99% of the time weird acting trailer lights is from a bad ground somewhere.

 

[trouttrooper]

oh, also. Does the trailer have the emergency brake away cable that locks up the trailer tires? I had one of those gizmos go bad internally that really screwed with me for the longest time. It physically didn't look bad so I never checked it, but I had the weirdest light issues with the trailer. I about chalked it up to evil spirits.

 

[NVW]

I"ve had a bad ground cause every light to flash when the turn signals were activated.

 

[SfcJones]

I am with the ground issue too. Strange things will happen for sure

 

[treegump]

ground was messing up and the wiring diagrams (I was using 3 different sources that seemed to be showing the same thing) was telling me to wire it differently then seen here: http://www.etrailer.com/faq-wiring.aspx . So...now I need to rewire both the trailer and my truck because I changed the trailer to make it work with my truck. yay...