wiring question?

I have a wiring problem right now on my tandem axle car hauler. I'm doing the wiring job myself. My question is does the dual filament light share one filament for turn signal and brake while other filament is used for running light? Because thats the way I have it wired. I'm assuming the tow vehicle will control the brake light and turn signal.

The problem right now is both right and left running lights are working, so are the brake lights. But when I try the turn signals only the lift side works. The crazy part is when I disconnect the left side and power up the right side the left side still works???? Some how power is back feeding to the left side while disconnected and still getting power.

Does anybody know what is causing this. I'm thinking a turnsignal is shorting to ground.... maybe.... or the light assembly is junk on the right side.

Any help would be great, Thanks in advance.

Dual filament bulbs share the same filament for turn/brake signal.

You're testing this using your tow vehicle, right?

Pull the bulb out of the offending socket and start testing the nodes without it in there, it could be a FUBAR bulb-I've seen filaments short against each other, illuminating the brake/turn circuit when it shouldn't be hot.

Dual filament bulbs share the same filament for turn/brake signal.

You're testing this using your tow vehicle, right?

Pull the bulb out of the offending socket and start testing the nodes without it in there, it could be a FUBAR bulb-I've seen filaments short against each other, illuminating the brake/turn circuit when it shouldn't be hot.

I swapped bulbs with the side that works. The problem didn't move with the bulb. I'll get new bulbs tomorrow and test all the wire for shorts to ground. I will also by pass the ground with a jumper wire back to battery. Just to double check my grounds are sound.

My gut feeling is the right side assembly is fubar. When I wiggle the light socket it flickers like a mofo. The lights came with the trailer when I bought it but that don't mean their any good. They are cheap ass made in China lights. I should just bite the bullet and get LED like the marker lights I've got for the sides.

I have a wiring problem right now on my tandem axle car hauler. I'm doing the wiring job myself. My question is does the dual filament light share one filament for turn signal and brake while other filament is used for running light? Because thats the way I have it wired. I'm assuming the tow vehicle will control the brake light and turn signal.

The problem right now is both right and left running lights are working, so are the brake lights. But when I try the turn signals only the lift side works. The crazy part is when I disconnect the left side and power up the right side the left side still works???? Some how power is back feeding to the left side while disconnected and still getting power.

Does anybody know what is causing this. I'm thinking a turnsignal is shorting to ground.... maybe.... or the light assembly is junk on the right side.

Any help would be great, Thanks in advance.

Yes, the bright filamant is brake and turn. In reality, wire it like "left brake and right brake", dont parallel them together. Only the running lamps can be paralleled together. On most domestic trucks (without amber turn) when you turn on the left blinker, it shuts off the left brake and coverts it to a blinker. This is done at the trucks turn signal switch. But if the tow rig has a seperate bulb for turn, and doesnt share the brake light, you will need to install a tail lamp converter.

And of course, make sure you are wired for a good ground, extra heavy if you are using electric brakes. Dont rely on the tongue for this.

As for your chinese lamp assembly, I'd certainy be suspect. LED's are nice.

What make and model truck and do other trailers work right when hooked to you truck. The other posts have gave some good info but if we knew the info I asked about we could do better.

What make and model truck and do other trailers work right when hooked to you truck. The other posts have gave some good info but if we knew the info I asked about we could do better.

Trailer wiring is standardized. Some backwoods person may hook it up any old way, but he can only tow his trailer with his truck. As for which dont need the converter, be any who doesnt have a seperate bulb for brake and turn on the truck. I dont know which models. In the beginning, it was imports who used the amber turns, now some domestics are now using a seperate bulb for turn, and its not always amber in color.

Trailer wiring is standardized. Some backwoods person may hook it up any old way, but he can only tow his trailer with his truck.

I know folks who have done this on purpose-that way they don't have to seem like a dink when people want to borrow it-"The wirings FUBAR, sorry":busted:

Everything my cousin has uses a pintle hitch-aluminum 2 place sled trailer and all. Not everyone's got a pintle setup.

Many vehicles are fused seperately for left and right blinkers...does the right taillight work on the truck when the trailer is disconnected? You may have popped a fuse wiring it...

On most domestic trucks (without amber turn) when you turn on the left blinker, it shuts off the left brake and coverts it to a blinker. This is done at the trucks turn signal switch. But if the tow rig has a seperate bulb for turn, and doesnt share the brake light, you will need to install a tail lamp converter.

I got the wiring figured out today. My ranger has a factory 4 pin and shares one bulb for turn and brake. I wired it to a 7 pin and tried it on my brother inlaw's new Tacoma and it worked. His tow package doesn't have an electric brake box but does have the converter built in I guess.

I'm going to be towing the trailer with my parents cummins turbo diesel. It to has a separate bulb for turn signal. Hopefully their OEM tow package has the converter built in too. Most likely does because they have it set up for towing their 5th wheel plus it can tow a dinky little utility with the plug adapter.

Before today I knew nothing about trailer wiring.... learning is cool:thumbsup:

Glad you solved it.

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