Switching truck/trailer reverse lights manually

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

MoParts

Member
Supporting Member
Joined
Jan 1, 2022
Posts
42
Reaction score
21
Location
Boulder Creek, CA
Ram Year
2018
Engine
Cummins 6.7 HD
Mods, please move if this is not the right sub-forum.

I am planning out some lighting upgrades for my truck and dump trailer. I live on what is essentially a narrow, windy logging road in steep terrain. I would like to be able to see where I am placing the wheels of the trailer as I maneuver even if I am operating in poor light. I don't expect that to be the norm but it will happen and I want to be able to see what I'm doing.

My thinking is that I can add downlights in the steps that are attached to and just fore/aft of the fenders, wire them to the reverse circuit and they could maybe light up the wheels and a few square feet around them plus be out of direct spray from the wheels. Of course I would have rear-facing lights too but it's the downlights that are my motivation for a switching scheme.

At this point I have upgraded reverse lights on the truck plus a bright LED strip over the plate. I live over 10 miles from the nearest street light and the upgrades are VERY effective, actually overexposes the backup camera in full dark. As a starting point I would like to be able to toggle this myself regardless of what gear the truck is in, for example to hitch/unhitch a trailer, look behind at how things are riding, etc.

Somewhere around the end of the month I am taking delivery of a dump trailer that will have reverse lights (plus) added and I would also like to control these manually.

It looks like the BCM outputs positive current for the reverse light circuits in the taillights, and the BCM grounds a wire to trigger the relay for towing backup lights which in turn feeds power to the 7-pin connector on the bumper. So, if using a brute force approach of just grounding or powering various pins I can find my way there with the diagrams attached. That's really not the way I want to do it though.

As an aside, while researching this I did find that the 7-pin connectors on the bumper and in the bed are wired directly together, so as a workaround I could wire up a spare 7-pin female connector with no connections except pin E shorted to A, and that would keep the trailer reverse lights lit as long as the shorting plug is installed. That would get me from my gate to the house along the twistiest 1/3 mile. I'm greedy though.

I would really love to control the truck's reverse lights manually too, and I want to explore the route of just telling the BCM what I want it to do, and not rewiring anything(except to set up the trailer).

I have seen CAN bus switches and read a bit about "upfitter" kits. Am I right in ASSuming that there ought to be a way that I could map an existing or new switch to control whatever functions like this? Or is it just a very narrow range of functions that can be controlled?

I don't want to give up any of my existing switch functions. I am not sure what approach to take, what options are there to pursue this goal, how to determine what codes need to be sent to control the BCM, and so on.

I'm opening this up to the hive mind since I'm sure many of you have solved at least a piece of this problem, or could point to some info that would help and I would be most grateful to learn from those who have been down this road. I think I am good on the basics like finding the lights themselves; etrailer.com seems to be a decent source. I'm technically pretty good too, lots of past electrical/electronic/industrial control experience so please no DMM how-tos... :D

ReverseLights.jpeg
TrailerReverseLights.jpeg
 

18CrewDually

Senior Member
Joined
Nov 17, 2019
Posts
2,012
Reaction score
2,583
Location
U.S.- New Jersey
Ram Year
2018
Engine
Cummins 6.7 H.O.
For less than $20 on Amazon you can get a remote control harness with FOB and wire it in the tongue box of the trailer to the battery. Then wire all your aux lighting to it. You can also "train" your overhead garage buttons in the truck to turn the lights on/off.
Glaretek Wiring Harness for LED Light Bar with Remote Control 12V 40A One Line Kit ON/Off Switch Relay for Fog Light Off-Road Work 10FT Length (Remote Control), https://www.amazon.com/dp/B07B3Y2D1X/ref=cm_sw_r_awdo_navT_g_S93H7FK37DD7MZMJFYTR

I used one of these kits for a transfer fuel pump on my truck and it works great.
 
OP
OP
MoParts

MoParts

Member
Supporting Member
Joined
Jan 1, 2022
Posts
42
Reaction score
21
Location
Boulder Creek, CA
Ram Year
2018
Engine
Cummins 6.7 HD
Interesting idea, thanks. Doesn't help with the truck reverse lights, and I'll be needing the extra opener buttons within the next year or two but I'll keep this in mind alongside the shorted connector idea. The truck reverse lights would be helpful for hooking/unhookig any of my several trailers so that's still important to me.
 
OP
OP
MoParts

MoParts

Member
Supporting Member
Joined
Jan 1, 2022
Posts
42
Reaction score
21
Location
Boulder Creek, CA
Ram Year
2018
Engine
Cummins 6.7 HD
Sorta thinking something like the CM-Series or VM-Series here: https://www.carlingtech.com/electronic-switching-products

They allow mix and match of direct switching or CAN/LIN bus operation. Anyone BTDT? I already had to bypass my security gateway to enable the cargo camera, I've been pondering whether I should move the gateway to a more accessible spot. It might be necessary for this project so that may be just what I need to get it done.
 
Top