Befuddled: Trailer Lighting Question while switching to new tail lights

[SeattleBob]

Hi All,
I decided to change out my existing trailer lights with LED's to get better lighting and to try to fix a fading blinking problem. The old lights worked fine as running lights and the right blinker worked okay but the left blinker was dim. I changed out the lights with the new LED taillights and now no lights work anywhere on the trailer (no side lights closer to the middle of the trailer, no tail lights, no blinkers). I am using the same wiring in the back as was their previous but am getting nothing. I checked the 4 pin connector with a test light on my tow vehicle and am getting juice through there. I tried the same test light on the wires on both back lights on the trailer and am not getting any juice through them. It is driving me crazy. I am towing it with a 2008 Honda Pilot. Could it be a bad ground connection? A bad fuse somewhere? Something else?
Any help or thoughts would be much appreciated as I am going a little nuts with this thing!
Thank you in advance.

 

[Silvertip]

Exactly why I recommend NOT changing lights just because there is a problem with the existing lights. Chances are a novice with electrical work creates more problems. Current needs a path TO each lamp from the tow vehicle as well as a good ground all the way BACK to the tow vehicle. Since nothing works at this point you either wired the lamps incorrectly or there is a bad ground. The ground is common to all of the lamps. Two of the other three wires feed the right & left stop/turn lamp and the third wire (brown) feeds the running lights (side markers and tail lights). Brown wire feeds the DIM (non-brake/turn) lamps. The brake/turn wires feed the BRIGHT lamps.

 

[lckstckn2smknbrls]

Replace all the wiring.

 

[ihc1470]

Silvertip is probably correct on it being a ground issue. That could be either at the towing vehicle or the trailer. Normally it will be the white wire that is used as the ground wire. You said you have power at your 4 pin connector on the towing vehicle. Where did you have the ground clip connected when doing that test? I would try it on the open pin at your connector. If you show power there at your other 3 terminals when connected that way, than the first place I would check is the grounding of the white wire on the trailer. The thing you have to remember with automotive wiring is the frame is one big wire so all connections that you make to it need to be clean. A star washer and some dielectric grease goes a long ways in making long last ground connections. Keep us posted as to what you find.

 

[Silvertip]

The trailer frame makes a good ground ONLY if every inch of the frame from wherever the white wire connects to it, to the frame area where the lights are mounted. In other words, if this is a tilt trailer, or the tongue is not welded to the remainder of the frame, any junction can present a bad connection point. A jumper wire around those joints can fix those types of problems.