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  1. #1
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    NO BRAKES! Or Lights! Or Turn Signals! 399TH

    Hi!

    I have a 2021 399TH that I've just sold. The new owners came to pick it up, plugged it in, and there's no lights, brake lights, or brakes turning on or responding on the RV. Their truck (a 2018 Ram I believe) says "check trailer brake wiring"....any thoughts? (I haven't tested with my vehicle, I'm on my way to do this presently...took place late last night...well, by the time we got that far). Thanks so much in advance! (Keeping the post up, but posted my reply well below. Not sure why, but it's there truck.)
    Last edited by mrbicycle; 11-13-2022 at 09:48 AM.

  2. #2
    Site Sponsor
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    With all of that stuff wrong, it’s likely either that they haven’t pushed the 7-pin in far enough, or maybe the trailer module in their truck. I’d guess the 7-pin.

    Edit: If they have a newly installed 7-pin in the bed, that installation is suspect too.
    Last edited by jkwilson; 11-13-2022 at 07:18 AM.
    John & Kathy
    2014 F250 Lariat FX4 6.2L SBCC
    2014 Reflection 303RLS
    SW Indiana

  3. #3
    Paid my dues 😁 FT4NOW's Avatar
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    Might want to plug it into the bumper 7 way and see if that change anything. Or plug it into your truck and show everything is good.
    2023 Momentum 398M-R
    2023 Ford F-450

    SOLD - 2021 Reflection 311BHS
    SOLD - 2017 Momentum 399TH

  4. #4
    Big Traveler
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    Quote Originally Posted by FT4NOW View Post
    Might want to plug it into the bumper 7 way and see if that change anything. Or plug it into your truck and show everything is good.
    Ya, plug it into your own truck before digging into your trailer wiring.
    2018 Dodge 3500 6.7 Cummins SRW w/Aisin
    2021 Reflection 303RLS
    New to RV'ing since 1997

  5. #5
    Rolling Along
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    You can actually plug the 7 way in upside down. My Ram was 180 out with my Titan. Check with your vehicle for sure before tearing into it.
    Randy and Kris

  6. #6
    Seasoned Camper msutoad's Avatar
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    Quote Originally Posted by Scott'n'Wendy View Post
    Ya, plug it into your own truck before digging into your trailer wiring.
    All good ideas, to check what you know worked which is with your truck. I have seen the bumper wiring work, but the bed wiring not, so another good place to work.

    One more involved thing I have seen with the newer trucks is the way it detects the trailer is connected. The brakes on one of my trailers needed new backing plates as as a result, the computer would not detect the system was connected. LIkely not your issue with a 2021, I highly doubt you smoked the brakes already. However this is food for thought for others here given the newer trucks rely on the computer so much to enable the trailer wiring to work. Just some info, not suggesting that’s your issue right now.

    I would go connect your truck first!!
    2023 Momentum 397TH w/Gen3 Goosebox
    2020 GMC Sierra Denali Duramax
    2020 F-450 Limited PowerStroke

  7. #7
    Long Hauler
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    Quote Originally Posted by stroguy View Post
    You can actually plug the 7 way in upside down. My Ram was 180 out with my Titan. Check with your vehicle for sure before tearing into it.
    Our last two plugs only connected in one position, a big lug makes sure of that. Tab A, Slot B type of thing.
    Howard and Peggy
    2019 Momentum 351M, and 2018 RAM Cummins dually 6-speed.
    His: 1999 Honda Interceptor
    Hers: 2013 Spyder ST-S

  8. #8
    Fireside Member daltontrio's Avatar
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    On my Ford, sometimes it won’t detect a trailer if I plug it in with the truck running. Have to shut it off, plug in the trailer, the start the truck. Sometimes, not always.
    2021 F350 CCSB 4x4 SRW with Air Lift springs
    B&W Companion Slider
    2021 Solitude 375RES-R w/ disc brakes
    Formerly REI 6 man tent


  9. #9
    Rolling Along
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    Quote Originally Posted by Hoopy Frood View Post
    Our last two plugs only connected in one position, a big lug makes sure of that. Tab A, Slot B type of thing.
    I agree but it sure did go in upside down and I got limited functionality. Forget what did and don’t operate but the spouse on her light check spotted it.
    Randy and Kris

  10. #10
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    Thanks everyone! Took my truck up to the RV...worked right away. So must be something with the truck as you're suggesting. Now they get to get their truck tested and figure out from there. Thanks again!

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