How To Troubleshoot and Fix Boat Trailer Lights that Don’t Work | BoatUS

You plug in your trailer lights every time
to test them before you tow your boat, right? What happens if they don’t blink when they’re
supposed to? Or, worse, they blink when they’re not supposed
to. We’re going to show you how to troubleshoot
them and fix what’s wrong. First, you want to physically disconnect the
tow vehicle from the trailer, including the chains. Otherwise you may be masking a ground problem,
which we’ll get to in a minute. The next step is to plug a tow vehicle tester
light into your vehicle’s connector. You can get these for as little as $10 online. If the tester shows a problem, you know it’s
with the vehicle, not with the trailer. Note the trailer wire color code. White is ground. Brown is the taillights. Green in the right turn and brake light. You can remember that green has an “r” in
it for right. Yellow is the left turn and brake light. And you can remember that because yellow has
an “l” in it for left. If the tester says the vehicle’s lights are
OK, the problem is with the trailer. But before we go any further, we’re going
to clean these contacts off with a little bit of emery board or sandpaper. And we’re going to squirt some contact cleaner. And finally, apply a little dielectric grease. Now we’ll try it again. Still no luck? Might just be a bulb burned out. We’re going to remove the bulb, clean these
contacts in here with the back of a pencil eraser or some sandpaper, spray with a little
contact cleaner. We’ll put a little dielectric grease on the
back of the new bulb, put it back in, and try it. If you still can’t get the lights to come
on, especially if it’s just one side of the trailer, it may be a break in the wiring. Folllow each wire and look for a break or
damage. On this trailer, the wires run inside the
frame, and we can’t see every inch of it. If you can’t find a break in the wire or you’re
not sure, you’re going to need to run a jumper wire. What we’ve done, the other end of this wire
is connected to the green wire at the front of the trailer. We’ve connected this to one end of our meter,
the other end of the meter is here. We’ll check for continuity on this green wire. And there we go. We have continuity, so we know this wire is
good. You can check each wire the same way until
you find a wire that’s not good. If you find a break in the wire, cut it and
use a heat-shrink connector to repair it. If the lights are dim or there’s other strange
stuff going on, like the brake lights flashing when the turn signal is on or they only work
sometimes, that may be a ground problem. We’re going to take the ground strap off here
and see if that fixes it. Find the ground screw on the trailer. It’s almost always a white wire. We’re going to take it off, clean it with
a little sandpaper or emery board, spray it with some contact cleaner, and put a little
dielectric grease for good contact. So now the next time your trailer lights act
up you’ll know what to do, and you won’t have to pay someone else to do it. Now let’s hit the road!

17 thoughts on “How To Troubleshoot and Fix Boat Trailer Lights that Don’t Work | BoatUS

  1. I also have a brown with yellow strip coming from left side of trailer light…5th wire??

  2. THANK YOU! I've gotten increasingly frustrated with bad troubleshooting videos. Yours is very well done. I appreciate you taking the time to make this. God bless!

  3. I've been working on mine for a week and it has been frustrating. Think I've made every mistake possible. Good to know there's a tester for the plug in at the rear of the vehicle. Thanks. Great video.

  4. Great video, now I know where to start with my dim right side stop and turn light.

  5. Thank you….most of the other videos only show the vehicle end…you went the extra mile and showed where the real issues usually are. . thanks

  6. LED LIGHTS are CHEAP so get off your wallet and put a completely new set on and move on.

  7. The video was good, probably one of the better ones I've seen, HOWEVER, you miss the mark on 2 items. 1) NEVER leave a bulb in place when performing continuity readings- the meter WILL READ THRU the bulb element. 2) when cleaning up grounds, clean EVERYTHING, that includes the bolt and or washer that pinches the solderless connector to the frame. These connections should be as clean as possible and look brand new. For the record I'm a licensed electrician and have wired dozens of trailers a d other DC related items on tractors and research equipment over the last 50 years…

  8. 1:10 1:30 , 2:50 ….you just applied di-electric grease on the metal contacts…which is not recommended unless you don't want your lights to work. Di-electric grease is an insulator, and should only be applied on the plastic/rubber mating surfaces, not on metal contacts. Check out these links for more info

  9. All my lights work except the left signal. The brake works though. (same bulb) What could the issue be?

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