Fish-Hawk.Net

Hi all ... Not sure if this is the right place to ask but I need some advice from anybody who knows about trailer wiring.

I have hooked up a different 4-pin trailer and there are no problems, so it's not the tow vehicle.

I have a Lowe trailer and the right side lights are not working properly. The trailer has a side light just behind the hitch (working), a running light on the fender (not working) and the tail lights (also not working).

I was wondering if it was a ground issue and when I removed the tail light, I noticed that it has 3 white (ground?) wires attached at the light. This really has me confused because I assume one of the 3 should connect with either the front light (working) or the other tail lights (also working).

Any ideas or hints would be most appreciated.

Thanks.

Im assuming you have checked to see if the bulbs are burnt out. A lot of times corrosion is the issue.

If your wiring is running through channel it may be some
critters have gotten in there and chewed through the wiring.
(speaking from experience, tried troubleshooting lots of other
things before finally discovering the wee critters home inside
the tubing )

Ugh, I had to do this in the spring. The above should totally be ruled out first, as obvious as it may sound (kinda like tech support asking if you re-booted).

If those are not the issues, diagnostics is easy enough. You will need a multimeter.

Yes each tail light has three wires - Signal/brake, running and ground. Not sure why yours is all white, maybe bought in bulk at the factory. Here is a basic schematic of a 4-post system:



As shown the green wire powers signal and brake, brown is the running lights. But if there are NO lights at all on the right side, my guess is that the two wires (green and the right side brown - or your trailer's equivalent) are severed / corroded somewhere between the side marker light and where the harness enters the hollow frame in the main beam.

To be sure. You said no problem with tow vehicle but rule it out with simple 1 minute test. Turn on your tow vehicle, and hit the right turn signal. Use your multimeter set to DC, black probe to the male post on the tow vehicle and red probe to the green lead (opposite side). If you get the fluctuating voltage you have ruled out problem with tow vehicle.

If passed above test, plug trailer lead to tow vehicle, with vehicle on and turn signal still flashing. Go to tail light. Disassemble. If the back side of the light is user serviceable (i.e. can be unscrewed), expose the metal parts. Identify the ground first, it should be short and terminate to the boat's frame no more than 3-4" from the light. If it disappears up into the cavity, give it a tug - the ground will have the least 'give'. Clamp black probe to it. Then sample both other leads with the red probe. If no action, chances are your right side needs to be replaced. If you do have action, bulb socket may be corroded. If the trailer light does not open, hopefully your multimeter probes have sharp tips to poke in through the wire sheath.

BTW mine needed full replacement and took about 90 minutes with minimal parts and cost - this being the big ticket item. Good luck.

Al

I would plug it into your your truck and turn on the 4 ways. Remove the lens covers on the affected lights. Wiggle the bulbs and see if they flash. If they do remove the bulbs and clean the socket with contact cleaner and replace the bulbs. If they dont flash, remove them and check the filaments, they will be burnt or cloudy , replace them regardless. The rear light tail/stop light will be an 1157. Make sure it is installed correctly. I have seen them jammed in backwards. Failing this replace the 4 pin connecter on the trailer.

Also remember that 80% of trailer lights issues are bad grounds. I would start with that!!!

Probably grounds in your sockets. Shine them in with some steel wool. I use electrical anti-oxidation paste. I bought some at Home Hardware cheap.