Trailer wiring problems

[Rahlow]

You have a ground issue, you will “see” the 12v with a meter, but without the ground there is no “flow”.  If you un-hook the trailer but plug in the harness you would have no ground for the trailer lights, same principle if it is on the hitch but there is a issue with the ground wire somewhere around the connector,,,,, maybe the reason the indicator light goes out when you plug the trailer in.

 

edit to say: should be a fairly easy fix if the problem isn’t internal to the plug, the grounding points should be easy enough to check.

[haggard]

My guess is bad ground. As others said, make sure the ground connection is clean (between the ground wire coming out of the truck and where it connects to the trailer frame, if that's how you're set up) - scuff it up with a wire brush or sand paper so you see bare metal. 

[mtsaz]

 go to this page---https://www.easternmarine.com/em_store/lighting/

scroll down so you can see the wiring color codes/what wire/plug location does what.  Then start checking continuity.  You can put the meter on the vehicle ground (somewhere--not painted metal) and on the trailer (not painted) when the lights are plugged in and you should get near zero resistance (ohms).  if you don't then you have a ground issue between car and trailer--and they have to be one and the same potential-- since the car battery is powering the lights on the trailer.  

 

Make sure that is resolved before you do anything else.  Once you have a good ground- between the trailer- and the car or truck- you can start isolating each individual light circuit- but it sounds like once you get your ground straight this will solve most of your problems.  

 

Once you know you have good ground, check for 12v.  Put the parking lights on and make sure the 12 v is coming thru ---even if the lights dont work- just make sure you have 12v.  If not- then its shorted or ---once again- there is a fuse or wiring problem to the connection between trailer/truck.   Once you get SOME light working- then its much easier to sort out the problem and get the right colored wire to the right light.  You don't know if your lights are all good, fuses all good, ground, or connections--so start with most likely (ground) and work thru the list. 

 

This is not complicated---frustrating at times yes- but not complicated.  Don't over complicate it.  Just think about it and study the diagrams on the website I sent you too--that is the standard for all boat trailers so once you get it right- your truck will properly light any boat trailer.  

 

 The ground has to be first or nothing will work.  Then- the powerIf you need help, we are here.  I am new to this forum, but I am an electrical engineer and it sounds like the other guys are equally as or much more knowledgeable than me- so there is plenty of help.  

Edited June 4, 2018 by mtsaz
typos

[12poundbass]

4 hours ago, mtsaz said:

 go to this page---https://www.easternmarine.com/em_store/lighting/

scroll down so you can see the wiring color codes/what wire/plug location does what.  Then start checking continuity.  You can put the meter on the vehicle ground (somewhere--not painted metal) and on the trailer (not painted) when the lights are plugged in and you should get near zero resistance (ohms).  if you don't then you have a ground issue between car and trailer--and they have to be one and the same potential-- since the car battery is powering the lights on the trailer.  

 

Make sure that is resolved before you do anything else.  Once you have a good ground- between the trailer- and the car or truck- you can start isolating each individual light circuit- but it sounds like once you get your ground straight this will solve most of your problems.  

 

Once you know you have good ground, check for 12v.  Put the parking lights on and make sure the 12 v is coming thru ---even if the lights dont work- just make sure you have 12v.  If not- then its shorted or ---once again- there is a fuse or wiring problem to the connection between trailer/truck.   Once you get SOME light working- then its much easier to sort out the problem and get the right colored wire to the right light.  You don't know if your lights are all good, fuses all good, ground, or connections--so start with most likely (ground) and work thru the list. 

 

This is not complicated---frustrating at times yes- but not complicated.  Don't over complicate it.  Just think about it and study the diagrams on the website I sent you too--that is the standard for all boat trailers so once you get it right- your truck will properly light any boat trailer.  

 

 The ground has to be first or nothing will work.  Then- the powerIf you need help, we are here.  I am new to this forum, but I am an electrical engineer and it sounds like the other guys are equally as or much more knowledgeable than me- so there is plenty of help.  

As of right now things are working. We didn't do anything different they just started working.