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Installation instructions

Towed vehicle charge line kit

part number 156-25

ROADMASTER, Inc.    6110 NE 127th Ave.    Vancouver, WA 98682    800-669-9690    Fax: 360-735-9300    roadmasterinc.com

All specifications are subject to change without notice.

Time Tested  •  Time Proven

                                                                                                                               

855407-01  11.17

CAUTION

  Read all instructions before installing or 
operating this device. Failure to understand 
how to properly install or operate the charge 
line kit could result in extensive property 
damage.

This kit requires…

  •  …a 6-wire (or a 6- wire to 7-wire) power cord between the 
two vehicles with matching sockets; and
  •  …an RV charge line kit similar in function to this kit in the 
motorhome. If a charge line isn’t already present in the RV, 
order part number 156-75, the motorhome charge line kit.

Installation instructions

 

1.

  Attach the included length of red 14 gauge wire to the 

center pin (the number 2 pin in Figure 1) in the towed vehicle’s 
power cord socket.
 

  Apply a silicone sealant to the socket terminals where the 

wires are connected; makecertain that all electrical connections 
in the socket are watertight.

  If the socket terminals aren’t sealed, stray voltage may 
energize the turn signal wiring. This will, in turn, activate 
any devices controlled by the turn signal wiring. Road-
master manufactures two supplemental braking systems 
(InvisiBrake and the 9700) which are so activated. Stray 
voltage may also cause inadvertent activation of any other 
device so activated. In the case of supplemental braking 
systems, severe brake system damage, loss of vehicular 
control and other consequential damage may occur.

 

2. 

Route the wire to the towed vehicle’s battery, or if the bat-

tery isn’t in the engine compartment, to the positive battery post 
in the engine compartment. Choose a route that will avoid the 
possibility of a short circuit or other damage to the vehicle.
 

  Cover the wiring along its entire length with the included

Purpose

  Once charge line kits are installed in both the motorhome 
and towed vehicle, they will help maintain the vehicle’s bat-
tery charge while in tow, supplying up to 15 amps of current 
to the battery.

Required tools

•  wire crimper 

•  side cutters

•  volt meter or test light 

split loom.

  Route all wiring to avoid moving parts, sharp edges, the 
fuel lines or hot components such as the engine or exhaust 
systems. Use the included wire tires to secure the wiring 
out of the way.
  Wiring exposed by moving parts, sharp edges or hot 
components may cause a short circuit, which can result in 
damage to the vehicle’s electrical system as well as other, 
consequential damage.
  Wiring which is attached in close proximity to the fuel 
lines may ignite the fuel.
  Failure to follow these instructions may cause property 
damage, personal injury or even death.

 

3.

  Find a suitable mounting location for the included circuit 

breaker — it must be mounted on a flat surface, within approxi-
mately 6" of the vehicle’s battery (the closer the better), at a point 
where it will not interfere with the operation of any components.
    Using the two included self-tapping screws, attach the 
circuit breaker.
 

4.

  Route the red 14 gauge wire to the circuit breaker and cut 

it. Strip ¼" of insulation from the end of the wire and crimp it 
onto one of the #10 ring terminals. 
 

5.

  Attach the terminal to the gold post on the circuit breaker 

(identified as ‘BAT’) with one of the included nuts.
 

6.

  Attach one end of the remaining length of red 14 gauge 

wire to the silver post on the circuit breaker (identified as ‘AUX’) 
in the identical manner. 
 

  Route this wire to the positive post and cut to length.

continued on next page

Figure 1

  

Pin 

Wire 

Motorhome/

 Number Color  Towed 

Vehicle

 1 ..........Blue ...........Brake monitor light

 

 

 

(electric trailer brakes)

 2 ..........Black .........Auxiliary/Charge

 3 ..........Green ........Right Turn/Stop

 4 ..........Brown ........Taillights

 5 ..........White .........Ground

 6 ..........Yellow ........Left Turn/Stop

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