I anticipate having to use a relay to power multiple devices using the remote turn on wire at B3 on the factory harness. I have never worked with relays and have never seen them installed. It is my understanding that if I would like to connect multiple devices to wire B3 then I should use a relay. I found THIS site very helpful.

I intend to power the following: two amps (daisy chained from one amp to the other), rca line driver and antenna amplifier.

1) Is a relay the correct way to connect the components or should I just connect everything to wire B3?
2) Can I use 18 gauge wire for everything?
3) What size fuse from constant 12 volt positive to terminal 87 (no clue what the draw is on any of the devices)?
4) Should I get constant 12 volt positive from my positive distribution block?
5) Should I ground to negative distribution block (which is grounded to seat pillar bolt)?
6) Would you use fuses between terminal 30 and the accessories?
7) Should I mount the relay to something? Any ideas where to mount it behind the head unit of a C6?
8) How should I split up the power from terminal 30 to the components? Wedge three wires into a butt connector?

Apologies for all the questions, but I do not want any electrical fires or other mishaps. Thanks in advance.

-Lucas

 

Do I need to use a relay or can I safely get away without one.

 

Use a relay if the devices that you are connecting draw more power than the circuit is designed for. When in doubt, just connect the relay.

You need to know what the sum of the power requirements are for the devices you'd like to power off the relay. Once you know that, you can choose the correct size wire to supply the power, and the correct size fuse to protect the wire.

Ground the relay to a ground point under the dash. (No need to take it back to the battery.)

Here's a handy chart that shows what size wire you should use based on the load requirement:



Don't let the USCG tag fool you... it's a good reference for DC circuits in cars, too.

A decent relay will cost about $5 and if you want to get a pre-made harness for it, that's another $2.50 out of your pocket.

You can mount the relay behind the dash, or use a tie wrap to tie it off to a wire bundle... just keep it from flopping around in there. When I had multiple devices to power from one relay, I would use a terminal board to distribute the power. In my truck, I used a fused distribution block that I mounted under the hood... but that's just one of a few different ways to do it.

I wouldn't try to put three wires into a butt connector unless it's designed to do that. Instead, I'd solder together a jumper harness and then cover the bare wiring with heat shrink tubing.

Good luck with your project.

 

if its just for device turn on 18ga is plenty

 

If it was just the amps, I'd come straight off B3, but adding the line driver and antenna amplifier I'd use a relay.

You can attach B3 to 86 and run 85 to the ground wire in the radio harness. Those are the coil pins, they don't pull squat for current.

Since you're only using it for remote trigger and the antenna gizmo you shouldn't have any issues if you tapped into the fused B+ wire in the oem harness as the +12v supply to pin 87. If you install a new fuse, I'd keep it at 5 amps or less (1 amp should be plenty).

You can do whatever you want from pin 30. If you put relay behind the radio you could put 2 wires into spade attached to 30, run one to antenna gizmo and other out to amps. At the amps you can just daisy chain the trigger wire from amp to amp to line driver.