Toasterstrudel

I have an 04 6-speed that I installed a BD exhaust brake on around 6 months ago. Around 3 months ago, it started losing consistency in its operation. It would activate consistently from 45 MPH and up and also consistently deactivate right at 35, and would randomly (about 10% of the time) activate below 35 but would also randomly deactivate. Lately, it's been less and less consistent. It hasn't functioned in a few days now, and I'm wondering if anyone can give me any ideas as to what the problem might be. The brake itself is operating perfectly fine, as when it actually was working, it would function fully normally, no lagging or slow engagement or half-engaging or anything like that. It almost seems like an problem that would be electronically based.
Any help?