Bought a trailer, 5x10 to haul mulch, dirt, rocks, toys ect. Good deal could not pass up. First hiccup was the position of the plug in for the lights on the trailer. I was a hair short. So after a couole runs to auto zone i got what was needed to bridge the gap i was missing.

Somplugged in the trailer, and no light. Ran the multi meter and tested for continuity and all was cool. Got fed up after a hour or so and threw in the towel. Looked up possible reasons why and found posts in the 30 amp trailer tail fuse to blow. So in the morning i went and checked the fuse and yep it was blown. So back to autozone for a new fuse. Installed, and this time hooked up,the trailer with truck turned off and lights off. Plugged in the trailer turned on the truck. No lights. Wtf?

Now the dude said all lights work so i am assuming they work, am i needing to replace something else to get these to work.? At a loss here

Mike

The lights not working sounds like a grounding issue, especially if it's the 4 wire flat plug. If the receiver or slide are new the powder coat doesn't allow it to ground thru the hitch. Separate ground wire is an option or create metal to metal contact. Not sure why the fuse is popping.

Is this a used trailer? 7 pin or 4 pin? Did you buy from a dealer or an individual? How old is it? What is the condition of the wiring? How did you "bridge the gap"?

Can you try plugging the trailer into the truck without your extension cord (gap bridger) to rule out your extension cord?

I suggest that before you connect to the 4Runner again that you inspect all the trailer wiring. Make a drawing so you can refer to it in the future. Indicate what is connected to what. If wires are different colors then indicate that too. If they are all the same color then make labels and label each end and indicate that on your drawing. Then look at the drawing to see if it's correct.

Look at the condition of the sockets and bulbs. Use your meter where necessary to check each wire from the plug to where it terminates and ground. When you're done, and everything checks out, you might want to use an external 12v source to check each run lighting the appropriate light (tail, turn signal and brake). Then check your 4Runner fuses again. Finally connect to the 4Runner and try again checking all lights.

Ditto the above - check the ground on your trailer.

Trailers can be headache, especially if they're older. Most are used infrequently and spend their time outside. Some good advice above. Check for a good ground, inspect wiring harness for any worn insulation / bad connections. Trailer light kits are pretty cheap, might be easier to replace with new than chase gremlins in an old harness.

I think "the dude" was being less than truthful. I was told the same thing about a trailer I bought years ago. The guy said the lights worked. Hell, one bulb was completely missing. We eventually found a bad ground as the reason the rest of the bulbs didn't work.

Ok sorry i am at work a d am getting to this just now.

Ok so it is a four pin flat on the trailer. I was just shy by 4 inches of being able to plug in so i bought a extension from autozone. Checked continuity of the extension all was good. It is a new reese hitch but i did not have it connected to the truck. I had the truck close and plugged it in. I will try connecting the trailer to the truck next time for the ground. I did check all the wires. They look in good shape.

I need to check under the wire nuts and see what the connections look like there. I was thinking of hooking a battery to the system to see if they do light.

Thanks for the ideas. Will report back next week after i get home from work

I doubt the hitch to ball mechanical connection is used as an electrical ground because (at best) it is a poor one. One of those 4 wires you mentioned should be a ground. Easy enough for you to check.

I had the same issue. Come to find out, I bought the wrong extension. Make sure the extension cable you bought has the ground connected at both ends. Some just come with a dead hole at one end where the ground wire has an eyelet instead.

Good to know. I will be checking on that when i get home. Seems wierd that there would be no ground but who knows

Try running a jumper wire from frame to frame then try hook up. If it still no good or blows fuse replace it all.

"Knock on wood"...I haven't had this much trouble with my second (or third) hand trailer. The lights were pretty busted up so I just replaced them with some cheap LED replacements from Amazon (like $40 for the kit). The designer in their infinite wisdom had made the mounts about an inch higher than the sides of the trailer. When loading anything bulky from the top (furniture, etc.) the lights occasionally took a hit. I got some scrap steel plate and made some "drop" brackets to move the new ones farther out of harm's way.

Definitely do the continuity checks across the trailer harness before plugging it back into the truck. If you can get a buddy to help maybe do a continuity check from the harness plug right to each bulb socket. The 4-wire setup is really pretty simple: ground, brake, left turn, right turn...that's it. I didn't trust trying to use the chassis as a ground so I ran a separate ground lead to each light fixture (just in case). No ground or a really poor one means nothing will light up or will be very dim. If you're popping fuses I'd imagine it's the other way around. One of the bulb sockets might have become so corroded you've got a straight path to ground (socket full of rust/corrosion).

I ran out of time when I installed my new lights and one of the old markers on the sides now flickers. It will be out and give it a sharp tap with my finger and it blinks into service (classy, right???). I've got the replacements in the garage but just haven't had the time/inclination to install them.