An Extra 100mA on the TAIL circuit. Potential Issue?

I need to ask a potentially inflammatory question. I know a lot of people have had electrical issues trying to patch in electrical accessories in the Gen5s. I've seen all the raptor light warning posts. So I'm definitely in tune to the fact that adding load to a circuit can cause the vehicle's computer(s) to have a stroke.

What I've not been able to successfully research is: Does anyone know WHICH circuits are susceptible to causing an issue if a load is added? And maybe even HOW MUCH? (It's a 2023 SR5P)

Specifically, I've got an accessory I want to turn on with the tail lights. I plan to power it with a relay wired directly to the battery and using an add-a-fuse on the TAIL circuit to power the 86 (coil) terminal on the relay. The relay I've got needs ~100mA to energize the coil. So it'd only be an additional 0.1A of load on the TAIL circuit.

I can't imagine a world where such a small additional load would cause an issue. However, I've seen enough horror stories for it to give me pause. Any insight would be appreciated.

 

FYI: It would be helpful if you can identify circuits that are CANBUS…which opens up another can o’ worms studying how that system works.

 

I’m not an electrical engineer so take this with a grain (or more) of salt.

SPOILER: I run my grill lights with relay, switch & fuses. My draw is minimal so I did use the TAIL circuit with an add a fuse.

IMHO from past experience if you use a relay to trigger a circuit it will only dray minimal.
That’s different than tying straight into a circuit with something that draws more amps than very minimal.
I always use relays and fuses and if I have to run a separate power source to the other side of the relay from an auxiliary power source to actually power your accessory.
Hope that makes sense!

 

If I had to guess, I’d say that anytime you tap into an existing OEM circuit(s) you are risking potential electrical problems. Seems most of the people here that have successfully added additional electrical circuits, do so by using a relay control circuit and powering the item directly off the battery.

 

Thank you so much for the response. Sounds like you've done exactly what I plan to do without issue. Obviously anecdotal evidence is only that, but it still gives me some confidence.

 

I would agree. The problem becomes though how to do you automate it? I'm already pulling the power for the device directly off the battery using a relay. I just need the small 100mA signal to activate the relay. I could wire up a manual switch (again, directly to the battery), but then my wife would have to turn on her neon pink grill rope lights (yeah, that's what I'm doing. lol) every time she wanted them on. That just seems tacky. haha. Sorry, typing it just made me realize how dumb of a project this is. It's gonna look cool though.

 

Thank you. This is the type of info I was looking for.

 

Since all you need is a small amount of current perhaps just tapping into one of the dash backlight (control switch(es), console illumination, etc.) circuits would suffice. That way when the ignition circuit is energized and DRL/Headlights are enabled you’d have a control signal to send to your remote relay.