so i just received my team associated sc10b that had a light bar already mounted, but wasn't wired. I soldered a receiver plug and plugged it into the receiver, but it didn't power on. I ended up wiring it directly to the esc plugs, but its not a steady current. So if I have the car at full throttle, the bar nearly turns off completely. After doing some research it appears i need a receiver controlled switch, but these need transmitters with a 3rd channel or aux channel, correct? Seeing as two of my 4 cars already have spectrum receivers, i was wondering, is the spektrum dx4c a good remote to have this setup and have all my vehicles on 1 remote?

One possibility is something like this, to provide enough voltage to the LED bar you have. No switching though. Even with something like a PicoSwitch proper voltage would be needed.

AnyVolt Micro Universal DC-DC Converter

LEDs usually take low voltage in the 2-3v range, in order to get them to run off higher voltages, a resistor is used. Not knowing what type of light bar you have or how the previous owner connected it, it's hard to say what to do.

I suspect there's already resistors somewhere on your circuit. They might be set up for battery power and that's why they don't work off your receiver. But your receiver isn't made for turning devices on and off from the + and -. You need something like the RC Lights 5090 Electronic Power Switch.

You have them connected to the ESC plugs on the battery side? Unusual that the voltage would drop that much. You might have a bad battery.

Just to clarify, which pins did you try on the receiver? Negative (black) to signal (white for many brands) won't give a constant voltage, but negative to positive (usually red) should give 5 to 6 volts with most electric powered RCs.

And the esc plugs, the ones going to the battery?

The previous owner said he only wired it up once and that was straight to the battery. I now soldered them to the ESC plugs on the battery side, and i don't think it's a bad battery, because it did it with multiple batteries. I should have mentioned that it was already fairly dim on 2s, but much brighter when i tested it on 3s.
yes, the ones going to the battery. That's just a temporary solution while i figure something else out. I soldered a receiver plug to the bar (red to red, black to black) and plugged it in to the corresponding pins. It looks sort of like a vanquish bar, but I'm not really sure.

If it is a Vanquish or similar 12v SMD led light bar, they are meant to run off a 3s lipo. They are woefully dim on less than 3s and they won't even light up on less than 8 (or so) volts. Running a 3s light bar through the receiver isn't really an option.

The simplest solution is running the light off a small 3s pack wired to a switch to turn it on and off. If you want to control the light from your transmitter, then get one of the turnigy remote switches, it just splices into the positive wire going to the light and handles 3s voltage. I have one wired up on my SCX10 to control the light bar running a 3s pack.

http://hobbyking.com/hobbyking/store...arehouse_.html

Yeah I noticed it was much brighter when I hooked up my 3s from my mini 8ight. I'll probably just get another battery light that one. So what I would do is wire it directly to the battery through a deans plug, then the remote would plug into the receiver and then I would be able to turn it on and off via the transmitter?

What about a bec?

Yeah that's what I'm thinking. I'm fairly certain it's a Vanquish now after comparing it to my buddies. I might just move it to my exo that has an external bec and get an rc4wd for the sc10b that is meant to plug into the receiver.
Either that or just velcro my small 3s in whenever I want to use the lightbar.