Specifications

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UBS Wiring Harness Handbook
This guide is intended to help end users pick an
electrical system that best fits their application,
while maintaining legal lighting requirements.
Before starting, review the Grote Know How
book, Basics of Electricity to get a general
understanding of current flow, proper wire
gauging and system grounding.
Use the Grote catalogs to determine the lights
and their locations required for your trailer.
Match their termination with the proper harness
and pigtail connections. Note that Grote UBS
plugs are designed to be interchangeable between
LED and incandescent lighting of the same
series. Always refer to the Federal Regulations
and requirements in this guide for proper lamp
position, quantity and color. Determine the length
of the trailer and note any other characteristics
that could effect wire installation, (examples:
sliders and lift gates).
Determine if your method for grounding will be
return ground or chassis ground. Refer to
section on grounding in installation tips section
of the Guide.
Specifying your System
Determine your type of trailer and refer to that
section of the UBS Wire Harness Design Guide.
In each case, Grote has designed optimal systems
for various types of trailers. The systems are
designed to be ground return with limited use of
pigtails.
In each design we have highlighted the required
harness to equip that particular trailer. Because of
the variety of designs and features, modification
may be necessary for some applications. Also,
end users may prefer to use different lamps or
route wires in a different manner, in which case,
we provide options. Along with the
recommended harness we offer various lengths
and plug configurations. Additional options for
rear sills, main harnesses and jumper harnesses
can be found in corresponding sections of this
guide if the recommended one will not meet the
end user’s design requirements.
Use the illustrations provided in the layouts to
see how connections are made and where.
Step One:
Determine trailer length, routing of cables and
wires and lamps and their locations. Now refer to
the section of this guide that represents your
trailer length and type.
Step Two:
Identify the harnesses needed for the “floor” of
the trailer, which would include the main or
mains and the rear sill.
Main harness: Grote offers both molded #10
ring terminals and molded push-on 0.180 female
nose box plugs for connection to the nose box or
front receptacle. Note that on a 28 foot trailer,
Grote recommends using a parallel main that
connects the front receptacle to the rear
receptacle without any interruption. For a 48 foot
to 53 foot trailer, Grote offers the option for
connection to the mid-turn lamps from the main
harness. The connection for the ABS unit is also
incorporated into the main harness.
Note: Additional main harnesses can be
found on pages 37 and 38 of this guide.
Rear sill harness: For this harness Grote has
provided two options. The first relates to the
actual installation of the harness, in that the rear
sill is offset to the roadside of the trailer or routed
down the middle. On the offset version, the
curbside leg is lengthened to route across the rear
of the trailer to the lamps. The second option
relates to the choice of lamps, which may be
female pin or male pin. The drop off of the front
of the rear sill is still the connection for the ABS
Using this Guide