Trailer Wiring Troubleshooting
hand turn signal and brake light
hand turn signal and brake light
and marker lights
4- Way plug
|With the lights on, when you
apply the brakes, all the lights on the trailer go out.
The ground connection is strong enough to
provide some lighting functions but not all. This is called a
weak ground. When the taillights and brake lights are used at
the same time, it creates the maximum amp load of the lights on
the trailer. Check the following to restore proper ground:
NOTE: It is not recommended to ground thru the trailer coupler
to hitch ball.
- The connector on the vehicle should have a ground wire
secured tightly to a clean surface on the frame. A wire
attached to the body or a surface with undercoating or rust
can cause a ground problem
- The connector on the trailer should have a wire from the
connector secured tightly to a clean rust free surface on the trailer.
- Each tail lamp assembly at the back of the trailer also
must be grounded. This is done in one of two ways. The first
is by a separate wire coming from the back of each tail lamp
assembly being secured to the frame. The second, and most
popular, ground is achieved through the bolts of the tail
lamp assembly. In this case, the lamp housing must be
attached to the frame of the trailer. There must be a
solid (clean and rust free) electrical connection.
- The last possibility to explore is in the trailer design.
If the trailer has a tilting bed, it is possible the ground
is not passing through the pivot point resulting in a poor
ground. The solution to this is to route a ground wire from
the connector at the front of the trailer to each lamp
assembly at the back of the trailer bypassing this pivot
|Wrong turn signal blinks.
|This is usually related to one of three things.
The first could be a short somewhere in the system. All wiring
and the vehicle connector should be checked and tested.. The
second, which is the most common problem, is a weak ground in
the system. Refer to "GROUND PROBLEM" above.
Third, the left (flat four yellow) side and right (flat four
green) side are connected in reverse.
|Always unplug boat trailer
when backing trailer into water.
|You should always unplug your boat trailer when
backing into the water. When the trailer lights are submersed in
water, it can create a short causing the vehicle fuses to blow
and/or result in damage to your wire harness and vehicle.
|Blowing fuses on vehicle.
|The first thing to check is that you are using
both Part 1 and Part 2 of the system. Both pieces, if a second
piece is included with your T-Connector, are crucial for correct
operation. The back up light fuse will burn out if part 2 is not
used. If Part 2 is being used, the fuse burn out is a direct
result of a live wire shorting to ground or an overload of too
many lights on the trailer. Check all wires for bare copper or
places where a wire could be pinched and calculate the amp load
your trailer is pulling. Most vehicles are equipped to handle
only standard lighting on trailers; one turn / brake signal on
each side and one marker light on each front corner. Check your
vehicle owner's manual for specific ratings.
|Turn signals are dim and
|When you add trailer lights to a vehicle system,
the turn signal amp load basically doubles. Most vehicles have a
flasher that controls the blink of a turn signal. The standard
flasher provided in many vehicles will not handle this extra
load. You should replace your flasher with a heavy duty flasher
(8 to 10 amps) and make sure the vehicle engine is running. The
flasher will slow down your turn signals and a running engine
will increase brightness of the lamps.
|Check all wiring insulation as it runs from the
front to back of trailer, concentrating on where the wire
enters/exits the frame or passes over ends of frame rails or
edges. Road vibration can wear thru the wiring insulation
at these points, shorting out the wire.
Major causes of lighting failure - http://www.grote.com/tech/maintenance/major_causes.html
Tips to prolong equipment lighting - http://www.grote.com/tech/maintenance/tips.html
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