Jake wiring

[Smiling lemon]

I believe the reason my jake brake has not been working is that my cab controller is dying, I tried to get it updated awhile back and the tech said he had to try it 5 times to get it to take the update.
Cm2530 x101
2016 W900
My plan is to bypass the cab controller and goto the ecm for wiring. I have the smart wheel and it looks like ecm activation is short signal to ground. My plan is to take a relay and wire signal from ecm to a ground and when I hit switch on the wheel relay will close to ground activating the Jake. Before I started doing something that could damage the ecm I wanted to confirm that is how it works. My other thought was to just bypass that all together and insite says the solenoids need to be supplied with 12VDC, so I would just put a switch that would activate the Jake solenoid directly. Just have to remember to open them back before throttling up again but still think it'll be better to have Jakes back.