A couple of years ago I did trailer light wiring on my 2001 Ram 1500.
I did a bunch of research to be sure that everything would be as I
desired. One thing I did learn is that all the automobile
manufacturers did some things their own way and did not follow the
normal industry wiring norms.
Among the things about Dodge wiring schemes is that according to their
specifications there is only a capacity for one additional filament
for each lamp circuit. As in just one additional brake light etc.
Anything more would supposedly void any manufacturer respoponsibility.
Expressed or implied. Accordingly I found relays that drew less
current than one bulb filament. I properly added a fuse to supply 12
VDC to 5 relays and used this as a source of 12 VDC for the trailer
lighting. I ran the control of each relay from the nearby wiring above
the spare tire. I made a small box/chassis for the relays and was able
to tuck it up in the frame near where the rear bumper attaches. It is
held in place with a foam block that I fashioned for a "jam" fit. I
also added a separate 12VDC circuit to supply 12 volts for any
possible use on any trailer. I located the brake light trailer brake
wiring and added the wiring for it to my 7 pin connector wiring. I
also wired the trailer ground, thru the 7 pin connector, from the
frame ground where the factory ground wiring attaches. A web site that
appears to have it together emphasises that a faulty ground is the
most common failure of trailer lights. A total of 4 additional #10
wires from the area of the underhood fuse block. I physically ran the
wires inside of the frame to an opening near the fuse block under the
Now with all this I have tested and used the 7 pin connector wiring
with several different tailers and it has worked everytime. I do go
above the minimun needs in all my electrical wiring. Most commercial
trailer and RV businesses do just enough to get your money. The choice
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