Trailer lights

[Mark]

I have been battling the lights on my trailer. The driver side brake/blinker doesn't work, but the tailight does with the lights on the truck on. I have switched bulbs, bought a new adapter, and recently put a new wiring system on a smaller trailer with the same resluts. Tried it on a different vehicle with the same results. I am 100% confused. If anyone has any ideas, I would really appreciate it. Thanks.

[caznik]

Make sure it has a good ground. At the tung end and at the light assembley where your problem is.

Rich

[Mark]

Will do, thanks for the advice.

[LongLine]

After 22 yrs, finally had trouble with my lights 2 months ago. Have never run a separate ground wire as ball is through a step bumper. No blinkers, no taillights. Had them on Saturday, nothing on Sunday.

Replaced bulbs…no improvement. Replaced the flasher in the fuse box…no improvement. Replaced trailer connector…no improvement. Replaced light coupler/harness under the truck with one I got on sale last year…no improvement. Ran to store & bought a new one (figuring the sale one was a dud)…no improvement. Replaced light fixtures…no improvement. Replaced all wiring on trailer…no improvement. Soldered all connections…no improvement. Took truck in for annual inspection and had dealer check out electrical system…no improvement.

Manually repositioned the trailer in my driveway and grabbed the ball/tongue. Oh, $hit…loose. Took it off & down to my workshop. Spit polished inside of ball locking area with rotary wire brush, then did same to trailer area where it attaches. Sprayed with WD-40 & torqued it back on.

Now the trailer lights are almost as bright as my truck headlights. :D

Duh! GROUND…

Tom B.

(LongLine)

One tip for bulb/socket longevity - (waterproof or not) Unplug your lights at the trailer before you back it into the water.

[Mike]

what kind of vehicle are you using to tow.

The reason i am asking this is: Vehicles with separate brake/signal bulbs(usually an amber colored lense) require a logic module to sort out the distribution of voltage to the lights on the trailer.

Also check the lights at night and see if:

with the running lights on, are the taillights on the trailer about the same brightness.

When you step on the brake pedal , the one side does not work does it not work at all, is it dim, does the side that works go dim.

Most wiring problems are caused by a poor ground connection usually on the trailer.

I am assuming you are using a standard 4 pin connector>>

To isolate wether the problem is the vehicle or trailer do this:

discinnect the trailer from the vehicle plug.

Tools needed>>> Testlight

>>> 12 volt battery( take the battery out of the boat)

>>> 2 long pieces of wire or "test leads"

4 prong trailer connector:

white = ground

brown = running lights

green = right rear brake/signal

yellow = left rear brake/signal

hook the clip end of the test light to ground( white wire)

turn on lights/ touch testlight end to brown wire.

turn on brake lights/ touch testlight end to green and then yellow wire

turn on left signal/ touch testlight end to yellow wire

turn on right signal/ touch testlight end to green wire

test light should illumanate brightly on all circuits, with the running light circuit(brown) being noticably dimmer than the brake/signal circuit.

To verify the ground on the connector with the test light clipped to the white wire of the connector, touch the positive post of the battery( need test leads). if the ground is good test light will illuminate brightly.

If the vehicle is ok. proceed to the trailer.

Trailer:

set a 12 volt battery near the connector, use test leads to connect battery to trailer plug.

connect neg battery lead to ground on connector(white wire)

connect positive lead to brown wire, running lights should illuminate.

connect positive lead to yellow wire, left signal/brake lights should illuminate.

connect positive lead to green wire, right signal/brake lights should illuminate.

example: If the left rear doesnot illuminate.

leave test leads hooked up.

ground the test light securely, remove bulb, touch thest light to the connector in the socket.

If test light does not illuminate, you have no power getting to the bulb(bad wire)

If test light illuminates you have a bad ground.

I am assuming that bulbs are ok.

Left side = driver

right side = passenger

Good luck, pm me if you are still having problems, or if this helps you out

Mike

[Mark]

I have a 99 Chevy 1500 that I tow with. Thanks Mike, and eveyone else for their help in this matter. I will be fishing Frankfort this weekend and will report on Monday.