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

The correct way to wire your breakaway battery, like the Hopkins Engager #20400, is to have the black wire from the battery connected to the 12V power on your trailer, and then the blue wire to your breakaway switch which, in turn, connects to the…

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Answer 2

The etrailer #CA-5400-B weld-on coupler you were looking at would be a great replacement for your current Parker Performance A-frame coupler. This coupler has a 2-5/16 inch ball and a weight capacity of 14,000lbs. I have linked this product to this…

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Answer 3

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 4

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 5

We have a large selection of trailer hubs with a 6 on 5-1/2 bolt pattern. In order to determine if any of these will fit onto the spindle for your trailer, you will need to remove one of the hubs and check for the bearing numbers on the existing…

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Answer 6

It's definitely possible to upgrade a trailer's axle rating to a higher rating by just swapping the axles. To pick out the correct axle you'll need to measure the distance between the hub faces and the spring seat centers and you'll…

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Answer 7

Thank you for reaching out! The best thing for your situation is to go with the 3,500 lb Dexter Axle #T3584F-8974 you are looking at. While you can upgrade your axles to the 5,200 lb #e55GR, you won't really see a benefit from it unless you also…

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Answer 8

In order to upgrade from a 205/75-15 tire to a larger size, the 225/75-15 which is what we offer you will need to account for the reduced clearance. The new size is 1.2" larger in diameter and .8" larger in width but you only need to…

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Answer 9

To charge the battery in the Engager Trailer BreakAway Kit, #20099, you can attach the wire from the 12 volt circuit on the trailer side 7-Way (1 oclock position on the back of the trailer side 7-Way where the wires attach) to the input wire on the…

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Answer 10

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 11

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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Answer 12

That's a very good question, we tend to be extra cautious and say to use 10 gauge wire because that would be more than enough. When you get into longer trailers that will end up using a lot of wire the heavier gauge wire becomes more necessary.…

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

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