View Full Version : I am having some trouble with my trailer lights

03-18-2012, 02:04 PM
It is a 4 pin (flat), I have power to the back of the truck, I plug in the adapter, and my parking/head lights don't work, blinkers work, brakes work... I have tried 3 different adapters its the same thing...I don't think it would be a fuse, since I can get power to the back of the truck? ...any ideas would be greatly appreciated.

Town Line Lawn Care LLC
03-18-2012, 02:16 PM
Bad Ground?

03-18-2012, 04:04 PM
well, my thought is, the adapter would still be ground through the truck, which seems to be working fine..?

03-19-2012, 10:07 AM
I would double check the ground on the trailer. A bad ground can make your lights do all kinds of crazy things! I just spent 5 hours last night on what should have took an hour replacing my lights with LED's and rewiring my trailer. I took where each ground was and ground it to bare metal with with an angle grinder, smeared dielectric grease all over it and bolted my ground wire down. I also replaced my plug that was very corroded. All lights are now working great! Before, my brake lights on the trailer would only work when the truck headlights were off. If the truck headlights were on, the trailer running lights would work but when I hit the brakes, EVERYTHING on the trailer went out!!

03-19-2012, 10:19 AM
Check your fuses. I had a similar problem after I fixed the ground issue.
Posted via Mobile Device

04-02-2012, 10:32 PM
You sat adapter. Do you have a 7 pin at the truckside? If so that plug may not be configured right. The adapters only pick up the power off certian blades,if you test at the adapter and have nopower on the brown wire but do at the truck that is your problem. It is not ground as you say your brake and turn lights work.

grandview (2006)
04-03-2012, 05:51 AM
Sounds like the ground to me.I have to clean mine every year from sitting out all winter.

04-03-2012, 10:19 PM
First test would be cking parking light pwr at the adaptor. Make sure you have it there. If you do, then your loosing it downstream of the trail plug. If your turn and stop work....i highly doubt it gound,,,,due to they all use the same ground.
Posted via Mobile Device

grandview (2006)
04-03-2012, 10:24 PM
Clean the inside of the 4 pin,sometimes you need to put some fresh scrapes on it work.If the trailer has a separate ground clean that up also.