It's likely you'll need some form of relay, like I use on SB Cruiser.
What voltage are the lights, and are they activated by grounding them or by providing power to them? What device provided the power and activation of them?
The CA input is active-low 0-5v. THat means it isn't designed for anything higher than 5v, and it's activated by grounding (since that is how most controllers also work, and so how most ebrake switches are designed and wired).
Are you going to be using any of the CA functions that require the brake input? If not, leave it disconnected and just leave your brakes wired the way they are.
Before you break into your wiring to put the CA in, I highly recommend making a detailed wiring diagram of your system as it is *now*, while it is working, including which color wires go to which pin on which connector if they are visible (often not the case).
That lets you both have a starting point for your new wiring, and a way to easily go back to a known working state should something go awry. If you also then update a *copy* of the diagram with changes as you make them (such as adding in the CA) you then have a much easier way to troubleshoot problems later on as they arise.
Then, decide how you are going to use the CA, which functions and how they will be setup. This determines your required wiring changes. Some things the system does directly now will instead have the CA inserted in the path, and some won't change. Once you know which is which, update that diagram copy (not the original) to show you the wiring changes, and *then* begin actually implementing them per the diagram.
It's harder to make mistakes this way...and some mistakes can destroy things, since you have mixed battery voltage and logic-level voltages and signals in various cables, and it is not difficult to accidentally miswire them...POOF.
Oh, also, if you figure out all the changes needed before you order the CA, you can also order all the connector tails you will need to just "plug it in" once those are wired into the system.
