Safety precautions before starting
- Park the trailer on level ground in an area void of all traffic.
- Chock front and back of at least one tire.
- Disconnect power source to trailer lights.
A thoughtful approach
- Check the vehicle’s trailer light connector before proceeding to
make sure it is working properly to minimize trouble shooting should you
experience trailer light issues upon completion.
- Remove/replace lights in respective pairs, to stay focused and
knowing the second one is always easier.
- Study each light before removing, observing housing, wire colors,
wire connections, and to make sure replacement light is correct.
- Keep all tools and parts together in a common carrier (bucket,
cardboard box, etc.).
- Fully complete each installation before moving to the next.
- Make written note of anything needing further attention upon
Get to work replacing those lights
Okay, it’s time to get those lights replaced. Although the process
won’t take long, be sure to start it when you have time and aren’t on a
schedule. It’s not the kind of job you want to start when getting home at
5:30 p.m. on a Friday afternoon with intentions of rushing through it so
you can go to the lake that night. However, it is a good project for just
about any other weeknight.
Here are a few steps to follow in their simplest from. Repeat the same
process for each light being replaced.
Either undo the wire connector or cut the wire, making sure to leave
enough length to reconnect the trailer wire to the new light’s wire.
Remove the old light and base (depending on style).
Attach new light and base to trailer frame, according to mount type
(grommet or screws).
Match and connect light’s wires to trailer’s wires. Ground to trailer
frame, if required.
If the light is a model that has its own plug, lubricate the male and
female connectors with the white grease provided and complete the
Once all lights have been replaced, also apply white grease to both the
vehicle’s trailer plug and the trailer’s plug to help protect each
against moisture and corrosion.
Give a walk-around inspection of all newly installed lights, making sure
all connections/plugs are connected.
Reconnect to vehicle power to test all trailer lights. Check trailer
lights for all the same functions of the vehicle’s lights: parking,
brake, turn signals and reverse (if the trailer has this function).
Make a final walk-around inspection, this time making sure no wires are
hanging down but are as close to the frame as possible so they won’t
snag on road obstacles.
Head to the lake with lights on and both you and your trailer beaming
Most Common Troubleshooting Fixes
* None of the trailer’s lights work
Re-check the vehicle’s trailer plug. An inexpensive circuit
tester is a good way to do this. It plugs into the vehicle’s trailer
socket and will indicate if power is reaching the plug. If the tester
indicates power at the vehicle’s trailer connection, then the problem
likely exists in the trailer’s plug. Inspect it for damage and replace
* Certain trailer lights don’t work
The problem is most likely at the light’s connection to the
trailer’s wiring. Check wire connections and/or the light’s own plug if
it has one. If after that it still doesn’t work, use a 12-volt test
light to make sure the trailer wire feeding the light does have power.
If it doesn’t, trouble shoot the trailer wire back to all connections
leading to the trailer’s main plug.
* Certain lights are dim, while others are bright
Definitely a grounding issue at the light itself. If you used
the old light’s base and just plugged the new one into it, check how the
base is mounted to the frame. If riveted, the rivets have likely
vibrated loose and contact with the frame is poor. Drill out the rivets
and replace with stainless or brass screws. If screws, they likely are
corroded and should be replaced. In either case, now go ahead and also
install the new base.
* All trailer lights are dim, or fade in and out
It’s a grounding issue at either the vehicle’s trailer plug or
the trailer’s plug to the frame. In both cases, make sure the white
ground wire is attached to the respective frame with a screw.
* After trying everything, one light still doesn’t work
It is rare, but is a possibility that the light was damaged
during shipment or has simply failed for some reason. If an Optronics
light, all you need to do is contact Optronics’ customer service and
explain the situation, and when and where the light was purchased, to
get a prompt replacement.
* Trailer wiring is a total mess
Don’t waste your time trying to patch and fix problems that come from
old, weathered wiring or from someone else’s makeshift patchwork when
you can easily run a brand new Optronics trailer wiring harness instead.
A helpful tip for doing this is to not pull your old wiring out first,
but use it to help feed your new wiring through the frame. Simply fasten
each side of the new wire to the old wire up at the farthest point
forward (basically the trailer’s plug), and then go to the farthest
point at the rear of the trailer (typically the ID light bar) and pull
the old wire out and the new wire into place. Repeat on the opposite
side. You will need to splice accessory wires at the appropriate
locations for side markers and such, but it is a much quicker and easier
fix for problematic wiring issues.