Parts Needed to Re-Wire 18 Foot Car Hauler Trailer with 7-Way Connector

Question

Question:

Im having trouble finding everything I need. Looking to re do all the wiring on a 18foot car hauler trailer with brakes on one axle. So I need all wiring with round, 7 pin connector, I should be able to use existing lights. And also any type of manual you would have to help me with wiring brakes since Im unfamiliar with that. Thanks.

asked by: Mike H

0

Expert Reply:

To re-wire your 18 foot car hauler with electric brakes on one axle, I recommend using a wiring junction box like # 38656 in order to make the connections from the lights and brakes. Then for a 7-way trailer plug, you can use the Hopkins # H20046. This connector has an 8 foot lead. The shorter 6 foot # H20044 or 4 foot # H20043 trailer connectors are also available.

I recommend using a circuit tester like # 40376 to determine the functions for any wires that are not known, as just using the wire colors may not be reliable.

Next you will need ring terminals to make all the needed connections in the junction box for your lights and brakes. For 10-12 gauge wires you will use # DW05741-1 and for 14-16 gauge wires you will use # DW05702-1.

You will then use 10 gauge wire like # 10-1-1, which is sold by the foot, to connect from the electric brakes on your trailer to the junction box. Either of the two wires coming from each brake assembly can be used for grounding to the trailer frame because brakes are non-polarized. You will use the other wire for power. You can use butt connectors # 05732-2 for the brake circuit wire. I have attached an electric brake installation video for you to review. Right around the 5:23 mark in the video you can see the wire connections being made.

I have also included a helpful article on trailer wiring as well as an installation video for the junction box that you may find helpful.

expert reply by: Chris R

0

Answer 1

As a general rule of thumb on a single axle trailer the hanger spacing should be around 3/8" shorter than the spring eye to spring eye measurement of your leaf spring. So for a 23-1/8" long leaf spring like the #e59SR you would want your…

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Answer 2

Spring Hanger location dimensions are normally figured by the manufacturer and provided with the spring hanger kit, that includes all of the parts for installing the springs on the trailer frame. I have provided a chart that shows the spring hanger…

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Answer 3

Spring hangers are intended to be welded on. Although you could drill holes in them and bolt them to your trailer, this would affect their capacity to some unknown degree and so this is not recommended. A local trailer supply shop will be able to do…

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Answer 4

The best way to power the interior lights in your trailer is with its own independent battery. You will not want to use the breakaway battery. The breakaway battery is only designed to operate the breakaway and will drain extremely quickly,…

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Answer 5

Hey Dan. The only DC to DC charger that you might be able to get away with mounting in a battery box is the OptiMate Smart Battery Charger item #MA99JR. It has a weatherproof case but it's still restricted to inside use only. An easier and more…

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Answer 6

Hey John. The tongue weight scale is only available on the Weigh Safe Hitch w/ Built-In Scale for 2" Hitch item #WS88VR or item #WS66ZR. These ball mounts do include both a 2" and a 2-5/16" hitch ball that swaps out quickly with the…

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Answer 7

The best way to get interior lights in your trailer is to have a dedicated 12 volt battery, and battery box like #329-HM318BKS mounted to the trailer. This gives you the power needed while you're not hooked to your truck. For lights I recommend…

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Answer 8

Hey Will, thanks for reaching out. What I recommend for replacing your 7-way is the following: - etrailer Trailer Wiring 7-Way Upgrade Kit w/ Junction Box and RV Style Connector #e99011 Wiring your connections thru the junction box helps keep them…

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Answer 9

According to Blue Ox, it'll take an experienced installer about 4 to 5 hours to complete the installation of their #BX1128 Base Plate Kit on a 2016 Jeep Grand Cherokee. The install isn't what I'd call super-difficult, but the installation…

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Answer 10

I took the measurements of the Multipurpose U-bolt, part #CE15504A, which you can see on the enclosed diagram. You'll note that the length of the U-bolt is 3 inches, which may be too short for your application. The closest sized U-bolt we are…

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Answer 11

It could be a tow package fuse on the vehicle. Use the owners manual to find the locations of fuses/relays related to the tow package wiring to check them and replace as needed. If the issue is not a fuse or relay then you can test the vehicle side…

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Answer 12

You can indeed test a trailer's electric drum brakes by directly applying +12V power from a fully-charged battery. You can apply this power to the hot contact on the trailer's plug (see photo please) or to an individual brake assembly's…

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Parts Needed to Re-Wire 18 Foot Car Hauler Trailer with 7-Way Connector

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