Forum Discussion

Carrera_man's avatar
Carrera_man
Explorer
Mar 18, 2015

Right LED tail light staying on

Here's an unusual problem that has cropped up in the past week. Can't get my right LED tail light to shut off. The trailer is not plugged into my truck. The only way I can get it off is to disconnect the house battery. I thought 12 volt house current is separate from truck 12 volt. I did hook it up to my truck and all lights work, except still can't shut off the right rear.
Its not as bright as it normal would be, almost like its picking up residual current from something. The right LED taillight is the only light that has this problem Any ideas?
  • RLS7201's avatar
    RLS7201
    Explorer II
    Mar 18, 2015
    What you are experiencing is an electromagnetically induced voltage. I had the same problem on my MH when I added LED tail/stop lights. A little resistance between the hot leads and ground will bleed off the induced voltage. I added a 912 incandescent bulb to each side behind the tail lights to bleed of the stray voltage. In my case the stray voltage caused the cruse control and torque convert clutch to malfunction.


    Richard
    95 Bounder
  • Carrera_man's avatar
    Carrera_man
    Explorer
    Mar 18, 2015
    Great info here.
    I'll check these suggestions this weekend, hopefully the weather will be decent enough for me to do so.
    Thanks everyone, I'll post what I find.
  • wnjj's avatar
    wnjj
    Explorer II
    Mar 18, 2015
    This guy was having the same issue (but without LED) lights. Like his, I'm suspecting an issue in the 7-pin plug. In your case, it only takes one loose strand of wire to touch the 12V pin and light up an LED bulb.

    The power for the turn and tail lights normally comes only from the TV but the connector also has the 12V charge wire from the truck which is connected to your trailer battery.
  • Artum_Snowbird's avatar
    Artum_Snowbird
    Explorer
    Mar 18, 2015
    enblethen wrote:
    I would check your connector to the TV on the trailers umbilical cord. You may find corrosion between the 12 volt line and the right "brake" light.
    The other place other than wiring is the junction box where the umbilical cord connects to the trailer wiring.


    I agree with this diagnosis. The 12 volt feed is right next to the right turn/brake feed. LED's take so little current that the opportunity to sneak across if the insulation breaks down is quite likely.
  • enblethen's avatar
    enblethen
    Nomad
    Mar 18, 2015
    I would check your connector to the TV on the trailers umbilical cord. You may find corrosion between the 12 volt line and the right "brake" light.
    The other place other than wiring is the junction box where the umbilical cord connects to the trailer wiring.
  • ScottG's avatar
    ScottG
    Nomad
    Mar 18, 2015
    donn0128 wrote:
    Ground issue!


    This.
    Ground is the only connection between the two circuits.
  • Bobbo's avatar
    Bobbo
    Explorer II
    Mar 18, 2015
    All the grounds are common. Every one. They all ground to the frame.

    I agree this is a ground problem of some kind.

    It would be interesting to check the light fixture's ground to trailer ground to see if you have current. Then check the light fixture's hot to trailer ground to see if you have current. THEN check whichever one is hot for polarity, to see which way the current is flowing.

    I bet you are showing reverse polarity between the trailer ground and light fixture hot.
  • Carrera_man's avatar
    Carrera_man
    Explorer
    Mar 18, 2015
    Thanks for the replies. If it was a ground issue wouldn't I have a problem with it when plugged into the truck?
  • j-d's avatar
    j-d
    Explorer II
    Mar 18, 2015
    Wild guess. Bad connection, corrosion, rusted ground somewhere. I think your problem is not on the hot side...

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