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Trailer Wiring

Last Changed 5/26/2010

One wiring trunk distributed from the Electrical Compartment is the wiring to the trailer jack.

TruckTrailertoRVTrailerCabling To start, here is a comparison with the standard Truck Trailer cable jack and the RV Trailer cable jack.  Only three wires are common.

The biggest difference is a truck trailer has separate turn and brake lights while an RV trailer has combined turn/brake lights.
Trailer Wiring You cannot just tie the circuits together because doing so would activate the right and left lights with any of the three signals (stop, right turn, left turn).  We could have used a couple of power diodes to provide the isolation needed.  However diodes drop .6 volts across them.  The wiring for the Volvo supplied enough current but following the basic rule of overkill in wiring, We decided to use a power tail light converter to insure full power to the trailer lights.
click on image to enlarge

We copied most of this from Jack Mayer.  Jack has a lot of good information on his site.  We will be coping a lot of the things Jack has done.

Hoppy 46255 We copied Jack Mayer and used a Hoppy 46255 powered tail converter.  The Hoppy converter takes the right turn, left turn, and stop signals in and puts out the combined stop/right and stop/left signals.  The Hoppy 46255 is powered so whatever we drive off of the Hoppy is not a load to the truck circuits.  We also used two terminal strips but we used the standard styles.  We find it easier to stack multiple connections using screw connections then stuffing multiple wires into the sleeve of the European style terminal strips.  We have the advantage of an isolated electrical compartment so the terminal strips are less prone to shorts.  We will probably put plastic covers over the terminal strips when we are done.

Note - there are cheaper non-powered versions of the Hoppy. The ones you will usually find in retails stores are the cheaper versions.  We found the powered Hoppys on the Internet. People who have tried the non-powered versions of the Hoppy have had very bad luck.

Hoppy 46365
The Hoppy 46255 lasted until it became a victim of TIF (Technician Induced Foul-up).  In other words, until Mark crossed a wire while checking lights.  The Hoppy 46255 is designed to protect the truck wiring but necessarily itself.  We acquired a Hoppy 46365 which cost a few dollars more but the 46365 is designed to protect itself as well as the truck.  The size of the 46365 is a little larger but it easily fit where we had the old Hoppy.
A new option for the Hoppy is a more resilient relay based unit called the Jackalopee from the makes of the ETHitch.  It comes with a cord to just plug into the regular truck trailer jack.  You add one additional wire.  It also comes with the trailer cable jack.

It is weatherproof so it can be mounted near the hitch.  It has indicator LEDs to easily troubleshoot any problems.

The Jackalopee costs a little more than the Hoppy 46365 but it comes with the cables and the weatherproof case.
click on image to enlarge

The Volvo trailer wiring is brought into one terminal strip.  The trailer wiring is brought into the other terminal strip.  The Hoppy converter is connected to the two terminal strips as well as the brake controller wiring.  This gives us a common place to connect the add-on lighting of the rig like the headache rack cabinet.

We mounted a circuit breaker on the distribution to control the +12 volt power circuit to the trailer and that is also attached to the trailer terminal strip.  We may add a Battery Combiner to the +12 volt trailer circuit to provide battery protection for the truck batteries while maintaining a good charge voltage.

Disclaimer: The information in this site is a collection of data we derived from the vendors and from our personal experiences.  This information is meant as a learning guide for you to  make your own decisions  Best practices and code should always be followed.  The recommendations we make are from our personal experiences and we do not receive any compensation for those recommendations.
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