This New Owner Is Worried About The Lights?  What About The Defective Hitch Latch Pin And The Un-Rated Safety Chain.

New-boat tinkering

August 17, 2013 - 7:20pm By KELLY TAYLOR




Kelly's new boat and trailer behind his 1997 Ford F-150. (Kelly Taylor)

We ventured into our first experience with trailering this month.

We bought a boat.

Of course, there were all sorts of issues with the used boat and trailer we bought: It’s why the boat we bought was about $16,000 less than the $19,000 a new one would cost.

Which for someone who likes to tinker is half the fun.

The first issue was figuring out why the trailer lights didn’t work. Sure, when we put on the turn signal, the tiny and far too dim marker light would flash, but that’s far from the ideal outcome.

Check the bulbs first. For this and step two, you need a DMM — digital multimeter. Set it to check resistance (mine has a setting for continuity — the meter beeps when the circuit is complete) and put the test leads across the bulb connections.

If you get very low resistance or a continuity-check beep on each filament, the bulbs are fine. Most trailer bulbs have two filaments — each goes to ground (the outer shell on the connector) and has its own connection in the centre of the back of the connector. Test between each connection and ground.




The second logical step in troubleshooting trailer lights is making sure the turn-signal and brake-light voltage is getting to the trailer plug at the back of the truck.

To figure out which connection is which, go back to your Sesame Street days and play “Which one is not like the other?” That, on a standard four-prong trailer light connector, is ground.

The other three are brakes and turn signals. Turn your DMM to check for voltage and set it to about 20 volts DC (exact settings will depend on your meter).

Put the black test lead on ground and touch the others as you apply brakes and turn on the turn signals.

If you get a flashing voltage on two prongs with the turn signals on and a steady voltage on the other with the brake pedal pressed, that part is working fine.

If these don’t work but the car lights do, check your owner’s manual: On my truck there are separate fuses for the trailer lights. If that part is fine, then the problem is in the trailer.

The first thing to do is check the ground connections. Trailer lights will typically take only voltage in on the wires and return the current to the truck through ground, or the body of the trailer.

This connection is almost always made through each light assembly’s mounting bolts. Also, check where the ground wire, typically the white one, connects to the trailer chassis at the front. This connection is as crucial as any.





Because the lights are often dunked into water when launching boats, they get wet. They also pick up crud flying from the wheels when driving and the result of both is corrosion that can cause the ground connection to break.

Unfasten the mounting nuts and scrape the connection behind that to bare metal. Put the nuts back on, tighten well and then try the lights again.

If they still don’t work, give up.

I mean, of course, give up trying to fix what’s there. You’ll save yourself a world of hurt by simply going to your local auto parts emporium and for about $14, buy a new wiring harness.

With the connector already installed, this harness was cheaper than a four-prong plug and 20-feet or so of four-conductor wire.

You could spend the rest of the week trying to find out where the bad connection is, or you could spend about half an hour running new wires. Your choice.

In my case, the previous owner used crimp-style butt connectors to connect the trailer wiring to the harness with the four-prong trailer plug.

Repeat after me: crimp-style butt connectors suck. Big time. The mechanical connection is iffy, water easily gets in and in short order, there’s so much corrosion there’s no electrical connection.

Worse, that water migrates via capillary action up the wires, causing those wires to get all oxidized and brown. I cut off about two feet of the old harness and still didn’t get to clean copper.

If you have to connect, use solder and heat-shrink tubing. But of course, the best connection is no connection at all — a continuous piece of wire will always be better than any kind of connection.

By the time I was done, I had unbroken pieces of wire from the front of the trailer to each light.

It was way easier than trying to troubleshoot each connection.








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