Trailer lights

[cargotrailer]

I have a problem with my boat trailer lights. Blinkers and brakes work but no tail-lights when i turn on the truck lights. The connector on my truck is the standard connector ( I think) It has 1 male/3 female connections. I think the male is ground (negative). I hooked my voltmeter up to the male and turned on my left blinker, checked the 3 female connectors and found #2 blinking, approx. 12 V. Then found the right blinker connector #3, it had 12V. Brake lights worked (#2 and #3 together constant 12V). So, connector #1 is the tailights, which makes sense, since it has two wires exiting on the boat connector side. When I checked #1 with my truck lights on I get no voltage, (i also checked every other connector with my lights on and nothing). I even went as far checking on the backside of the connector to make sure i didn't have a loose wire inside that little plastic housing. (I bet this is all confusing)
I always assumed that the trailer hook-up just piggy backed off of the truck tail lights. Is there a fuse some where between the truck lights and trailer connector? Or am I totally missing something on the boat side of the connection?

Each trialer light has a single bulbs with two filaments per bulb, all filaments looked to be intact.

Hope somebody can help. I read CFF everyday, don't post much. (Hope this is the right category)

Thanks in advance.

 

[Buoy-Master]

Check your white ground wire on the truck and trailer. Make sure they are getting a good ground. Running lights work off 1 hot and the main ground. The rest pretty much work off hot and designated grounds. (stop , turn ect..)

 

[cargotrailer]

I checked the hot for the running lights directly to the ground on the connector. ( All of this was checked without the boat hooked up) If the blinkers and brakes worked with that ground then it must be good, right?

 

[Buoy-Master]

have you checked your truck plug with a voltage meter?

 

[cargotrailer]

Everything in my first post was just checking the truck plug,,,,,,sorry if that wasn't clear. I figured I would start checking voltage at the source, I got voltage on the blinker/brake light terminals #2 and #3, but nothing on #1 of the truck plug with the truck lights turned on.

 

[Buoy-Master]

Not really sure what the problem is...</p>

If all connections under the truck and on the trailer are fine...could very well be a truck fuse. Some new models have 2 seperate fuse boxes. Might try looking at them. I know Fords have fuses just for running lights!(been there , done that)</p>

Hard to say without being able to look at it.</p>

 

[TheFisherman]

If the lighting system worked correctly before then it can only be a connection or a fuse problem... I'd strat with the easy part - the fuses, then start looking for a broken wire, poor ground, broken connector, etc.

 

[Triton4Bass]

i have kind of the same problem, except my brakes and blinkers work all the time, but my running lights on the left side only work sometimes. can anyone figure that out? ..... and yes BBass, my ford loves those little fuses too! emoScratch

 

[hl&s]

Hi Cargotrailer,

Add on trailer plugs are generally piggy-backed onto the existing wiring and are not additionally fused. The original factory fuses will protect the additional circuits.
Factory tow packages sometomes have additional fuses and relays to protect the circuit and supply additional current to the trailer bulbs.
Plug wiring colors are usually green and yellow for left and right turn signals, white for ground, and brown for taillights. Do the truck taillights work? What kind of vehicle is it?
If all factory fuses are good, look for additional fuse boxes and check them. Trace the taillight wire back to its connection to the vehicles wiring and check for voltage.
Some later model vehicles also use a power convertor to supply the extra voltage to the trailer lights thus protecting the factory wiring and components from overload. It's usually wired in where the trailer plug wiring is added to the original wiring.

Good Luck,
hl&s

 

[cargotrailer]

My truck is also a Ford, 2002 Sporttrac (sort of a truck). The wiring is as you described hl&s. The truck lights work fine. I tried to trace the wiring back from the truck connector, but they all sort of run together with other wire harnesses inside those black plastic tubing things. I did find a black plastic cylinder shaped thing with wires running to it. It is about 1" in diameter and 3" long. Looks like it comes apart in the middle. Could this be a fuse housing? My owners manual doesn't have a single word about fuses and I can't find a diagram anywhere.

 

[bosco]

Did you rule out the connector as being faulty. I know you checked for a loose wire but it may be some corrosion down in the bottom of the connector.

 

[cargotrailer]

Just found and corrected the problem. I decided since I couldn't find a fuse box diagram that I would just check them all. About halfway through the process I found a blown 15A. Ran to the auto parts store, replaced the fuse, and lights are working now. Thanks for all the ideas, nothing like a good brainstorming session. Hopefully in the future I can contribute more to CFF, but keep up the good work. I look forward to reading new posts every morning with my coffee.

 

[Buoy-Master]

 You wont find a Ford burning down because of wires. They have enough fuses to protect a house!</p>