Lighting Troubles-Need a bit of help

[Capebuild]

Hello. I just installed all the lighting (left and right brake/turn signals, 3rd brake light and license plate light). I had checked all prior to installation and all worked great. Now that I've got it all installed on the hatch the 10 amp fuse keeps blowing.

A few things I can offer in looking for suggestions to check:

1) When a new fuse is inserted and I put the emergency flashers on, they work on the tail lights and half the 3rd brake light (the other half is missing a wire hook up as I forgot where it goes but that is most likely not the root of the main problem).

2). When I step on the brakes the tail lights and 1/2 3rd brake light work as they should.

3). When I go and turn on the headlights, fuse blows.

4). If I hook up a stray 12 volt battery to the wires that feed the license plate light, that light illuminates.

It seems putting on the TV's headlights causes issues. So that's one thing.

There is one common wire (other than the white ground wire) that goes to a both tail lights and the 3rd brake light. If I put a meter set on continuity and touch the white wire and that other common wire, I get a beep sound. Is that the way it should be? Any other wires touched while also touching the white ground, no beeping. This other common wire goes to both tail lights (both have 3 wires) and the third brake light (which has 4 wires).... so is it normal there's continuity with that common wire and with the white ground wire?

I know without being here it's probably difficult to help diagnose, but any suggestions to try would be a help.... especially using the meter to check the wiring (which I don't really have much experience with).

Thank you very much.... I appreciate any help offered.

John

[pchast]

Continuity is not going to help find the problem. Please first unhook the trailer and see if the TV lights fault by themselves.

Now rig a battery supply to the trailer through a fuse and test each circuit to the common ground back to the battery. You should be able to identify which circuit is faulting, if one is.

Otherwise,,, your head light switch supplies the running lights and tail lights directly. The turn signals and brakes and flashers are secondary systems and may not be involved with the problem.

The most common problem is crossed wires that bypass the individual light unit causing a short. This can be caused when it's attached to the trailer right at the back of an individual light unit.


Let us know what you find please so that we can provide more pointed suggestions.

[Capebuild]

Pete, thanks so much for replying to my post.
As I was lying in bed last night at 1am with insomnia thinking about this and wondering why the fuse blowing when the headlights were illuminated.... DUH... then it hit me.
There are four sets of wires, two sets coming off each side of the trailer, to feed the marker lights. I had taped up those wires when the aluminum siding was installed and hadn't unwrapped them. The ends of those wires were cut back and I'm sure in one of those sets, if not all 4 sets, those bare wires are touching and probably causing the short when the headlights were turned on (those marker lights are not yet installed. I'm just testing the light fixtures on the hatch for right now). I'll have to unwrap those wires and spread them apart and try all this testing all over...... if that's not the issue I'll be very surprised..... but hopefully that is what's causing the problem and not something more mysterious.... at which case I'll run through your suggestions.

Thank you again for your help.... I do appreciate your responding.

John

[Capebuild]

Just a follow up (and a happy one, at that). I removed the tape that was holding the marker light wiring together and, lo and behold, one of the sets of marker wiring's bare wires were contacting one another. Separated those wires and tried all the hatch lighting once again. All worked great! An easy solution, although yesterday was frustrating as can be going through half a dozen fuses.


John

[pchast]

Yes it can be frustrating...
Glad you worked it out.

[troubleScottie]

You might need another piece for this puzzle.

Generally, the 3rd stop light bar takes a common, a stop, running lights, a left turn and right turn.

The connection to the trailer has a common, running lights, left/stop and a right/stop ( for a 4 wire feed; and 12v auxiliary, brake, reverse for a seven wire feed )

There are devices that separate out the stop from the turn signals. Like "Tekonsha 2 to 3 Taillight Converter for Connecting Tow Vehicles w/2 Wire Systems to Towed Vehicles w/3 Wire Systems" https://www.amazon.com/dp/B001GKQZQG/?coliid=I2UGR7OKXUDYSO&colid=1VCAM73QMKAG8&psc=1&ref_=lv_ov_lig_dp_it There are others. Not promoting any particular brand.