$25 question

starcrafttom · Posted: Mon Oct 13, 2008 12:49 am Post subject: $25 question

Ok so here's the clue's to the question. I have a f350 king cab. with a camper on it and towing the boat behind. all lights work but the left turn signal on the camper and the boat. The left turn on the truck works fine. so wheres the problem? yes I found it but it took over a day and it surprized me.

Sea Wolf · Posted: Mon Oct 13, 2008 1:06 am Post subject:

Tom-

You're saying that the left turn signal (front and rear) on the truck work fine, but that the separately mounted turn signal on the camper body and the turn signal on the boat (which is also the brake light, right?) don't work?

Are the trailer lights and camper lights connected to the same trailer wiring harness (tow package) on the truck?

If so, this connection could be faulty, or one or the other of the camper or trailer lights for this circuit could have the hot wire grounded out somewhere, perhaps (through corrosion) in the light bulb socket, which would not light that bulb and also take all the voltage and current to ground so that the other bulb doesn't light up.

So how's that for a wild guess?

Joe. Teeth

starcrafttom · Posted: Mon Oct 13, 2008 1:16 am Post subject:

nice guess. but you dont quite have it. yes the truck lights front and back work, but the turn light on the camper ( not a trailer but a camper) do not work and when you hook up the boat trailer the turn signal does not work. and all the light bulbs work fine if mover to other sockets. Sorry forgot that part

Sea Wolf · Posted: Mon Oct 13, 2008 1:51 am Post subject:

Tom-

Do the camper lights run off taps into the light circuits on the truck, or do they connect to the trailer tow harness/package installed by the factory for the towed vehicle?

And how are the trailer lights tied into this? Into the factory trailer tow harness or to the lights on the camper?

How are the camper and trailer grounded? Just through contact of the metal bodies, or are there positive connections through wire connections everywhere?

Are all the pin connections intact in the plugs, and are all the wires connectded to the right pins (instead of a brake wire connected to a back up light circuit, for instance.)

You (or me at least) usually need a continuity tester and a digital volt/ohm/ammeter to track down this kind of problem unless visual inspection shows up some glaring error.

Of course, there always some crazy possibilities, like someone having connected the camper and trailer lights in series rather than parallel, but there are a lot of strange possibilities behind those kinds of doors.

One thing that sometimes happens is that a poorly grounded brake/turn light bulb in corroded socket will run current back through the tail light filament in the same bulb and wind up lighting it up and the tailing light bulb on the other side, and even perhaps the side marker lights, which are on the same circuit.

Things can get weird in a hurry!

Guessing about this is difficult to the degree that I don't have physical access to all of the information and the ability to test out each circuit for correct or possibility erroneous circuitry/connections.

Joe. Teeth

Swee Pea · Posted: Mon Oct 13, 2008 7:17 am Post subject:

Test the connection from the trailer to the truck. Mud daubers deposit mud in the connectors making it a bad connection. I had the same problem. Clean the mud/insect crud out. It worked for me.

John
Swee Pea

Minnow · Posted: Mon Oct 13, 2008 8:02 am Post subject:

My Chevy has a separate fuse for the trailer signal lights. Same for Ford?

Sea Wolf · Posted: Mon Oct 13, 2008 11:17 am Post subject:

Minnow-

Good guess!

I had forgotten about the extra fuse panel under the hood!

My Durango has a "user available" fuse panel under the dash, like everything else, but also a major "electrical distribution box" under the hood. It has more re-settable circuit breakers than fuses, but some of both.

I remember I had to replace a brake/turn signal fuse from the factory tow harness once, myself. Took about an hour or so to figure out why the outlet terminal at the trailer lights plug was dead, while the lights still worked on the tow vehicle.

Joe. Teeth

Dreamer · Posted: Mon Oct 13, 2008 1:04 pm Post subject:

Tom,

I seem to remember that Ford used relays for the auxiliary lighting on the trailer wiring harness. If the one for L. turn and brake light was bad... there you go!

wailedcentipede · Posted: Mon Oct 13, 2008 1:38 pm Post subject:

replace the bulb Razz

Will-C · Posted: Mon Oct 13, 2008 1:50 pm Post subject: 25 dollar question

Tom,
I would ask Jonny myself. You know the guy blowing out the C-Dory's at not so good prices. He seemed very knowledgable and willing to help.
Laughing

D.D.

ccflyer · Posted: Mon Oct 13, 2008 1:59 pm Post subject:

I have this problem on my Tundra. Both lights checked out on the trailer but when I hooked up, the left directional on the trailer doesn't work Cry

Since I only use the trailer to launch/retrieve once a year I try to just make right turns

Grumpy · Posted: Mon Oct 13, 2008 2:21 pm Post subject:

I have a Chevy connected to a 3 axle trailer with electric over hydraulic brakes. It took several hours of web research of user groups to determine that I had to dig around in the engine harnesses to find two separate wires that I had to connect to two separate bolts (no nuts supplied !!) in order to make it all work.

Nothing in the vehicle manual.

Hard to imagine on a truck that has a full "Towing Package".
Also hard to imagine WHY. All they saved was two nuts and a bit of newsprint in a manual that is already 80%, genetic diversity reducing CYA to avoid litigation.

My bet is something of that nature Beer

Merv

starcrafttom · Posted: Mon Oct 13, 2008 2:52 pm Post subject:

Joe was hitting around it like a shot gun toting drive by gang member but I think Minnow hit it right on the head. I already fixed this problem but it took two days of banging my head against a trailer hitch and finally having my dad stop by and goes over it all again. My dad got under the truck with his volt meter and tester to start the long process of find a bad ground. He got to looking and noticed that the trailer lights were not spliced into the truck lights but a whole different wiring harness coming from the front of the truck. Which, you guessed it, goes to its own fuse box. When I saw that the truck lights worked I never looked for a blown fuse. I did not know that ford and others used a totally separate harness for the trailer lights. Good idea, that way if the trailer blows out a light you still have lights on the truck, I just did not know of it. So Minnow is the winner and the first guy I call the next time I have trailer issues.

Grumpy · Posted: Mon Oct 13, 2008 3:08 pm Post subject:

Tom,

The two wires I mentioned in my post go to separate fuses on the Chevy so in my case I have a fuse for the brakes and a fuse for the lights.

All designed by Confucious, and good to know.

Merv

CW · Posted: Mon Oct 13, 2008 8:19 pm Post subject:

Pretty sure it is haunted. Better exorcise the bad demons out of there.... C.W.