Question on fused trailer battery wire on 2005 CTD

[seafish]

Well, I am finally tackling a project that involves hooking up a second type of 7 pin trailer plug on my Reunel rear bumper, and more importantly, 2 more par 36, 50w back-up lights on the same bumper. At this point in time, I also have the puny OEM back up lights, as well as 2 additional 50w lamps in my Caravan camper shell. Right now the camper shell reverse lights are hooked up to the oem reverse light circuit with a pigtail wire from one of the oem sockets. You should also know that on my 2005, I thankfully do NOT have the sensitive TIPM to control the trailer harness, but instead have fuses in the underhood fuse box that include --



(1) 20a trailer battery circuit, always hot

(2) 15a fuses, one for each side of the trailer turn/stop,

(1) 30a trailer brake circuit,

(1) 20 amp trailer running light circuit.



Unfortunately, as far as I can tell, the trailer reverse lights at the oem trailer plug are factory wired through the 15a truck reverse light circuit-- (as indicated by when I pull the 15a truck reverse fuse, the reverse light wire at the trailer plug also loses voltage and there is no trailer back-up light fuse listed in the fuse box. )



So my inclination, in trying to keep the wiring safe, yet simple, is to use a relay triggred by the oem back-up light wire to give power from the 20a always hot trailer positive wire to BOTH the New bumper reverse lights, as well as the camper shell reverse lights, which total approx. 16 amps. Obviously, I will first remove the already installed pigtail that connects the oem reverse lights to the campershell mounted reverse lights, but my question is this...



Will I be overloading the 20a trailer positive circuit if I shift into reverse while pulling a trailer that is using the trailer positive to charge it's battery??? Essentially, I need to know ehat controls the current that a trailer battery draws through this circuit. Is it simply battery draw??



I could, of course, always run another 12 ga wire back from the truck battery to the bumper mounted relay, to power the 4 back-up lamps, but I am trying to avoid this if I can do so safely.





The way I am suggesting doing this means cutting and soldering only 2 wires from the trailer plug extension that I am installing, running them 12" over to a back of bumper mounted relay, and then running 1 wire from the relay to each of the 4 reverse lights. It is pretty clean and simple if it will not overload the circuit on the rare occasions when I am pulling a trailer with a battery... most of my trailer pulling is flatbed without a battery.



Whaddya guys think and know???



TIA

 

[HBarlow]

The 20 amp trailer charge line is primarily used to maintain and recharge a trailer battery. If you have plugged in a trailer with a discharged battery the trailer may be drawing fairly high current on this line.

It would probably be wiser to buy and install a Painless Wiring Fuse Block from Geno's and run a new separate power line to the reverse light relays you are planning to install. That's what many of us who pull trailers have done.

Once you have the accessory fuse block with seven power sources, both fused and always hot, you will be able to install several more lights or accessories you may have thought of but never got around to.

I use mine for CB radio, dc to ac inverter, accessory bed lights, etc.

 

[RVTRKN]

I can't comment on the wiring circuits, without looking at your system and the wiring diagram. But I can recommend going with LED lights which take a lot less current and not effect your small AWG wiring. If you change the tail lights on your truck to LED, you will have to install a resister so your turn signal failure chime won't activate. Hope this helps.

 

[seafish]

Thanks for the reply guys.

HB, the scenario which you describe was exactly the concern that prompted me to ask the question. I do have a painless kit already on the shelf in the garage ( and even the TDR issue that includes the install article) , just do not quite have the time to install it right now. I guess what I'll do is just continue hooking up the trailer plug, but leave the back-up lights until I can hook up the painless kit.

Thanks to both for the advice!!!