Cruise King Fast Idle not working.

[JVH]

Hi All,
I have a 1995 American Eagle with the Cummins C8.3L mechanical engine.
My coach came with an Econo Cruise control.
When it went bad, I purchased a Cruise King, King Cruise 2500 kit that was made to be a replacement. I was able to reuse the wiring to the front and had a replacement switch plate made to fit the spot in the dash where the old controls were.
The unit has worked well for about 5 years. However, I have never been able to get the fast idle feature to work reliably. After examining the troubleshooting documents on the website, I replaced the Allison output speed sensor. Sometimes the fast idle will activate but then shut off after a few seconds.
The troubleshooting notes say that the unit is picking up noise and to add a filter to the speed signal line.
I can find no information on what filter and how it should be installed.
Any assistance would be appreciated.

[153stars]

I would imagine to start with supply power 12v. Look for 12V DC inline noise filter that's made for car radio. Ferrite core clamps can reduce noise on other wires.
https://www.amazon.com/dp/B078SNR9XB...7Y57XS3YG6W5M0
Be careful not mess up remove all power before repair. I don't think there is anymore support to repair King Cruise besides some very limited NOS.